JP3705246B2

JP3705246B2 - Hot water system

Info

Publication number: JP3705246B2
Application number: JP2002193692A
Authority: JP
Inventors: 富雄三宅; 知明西川; 利彦大林
Original assignee: Noritz Corp
Current assignee: Noritz Corp
Priority date: 2002-07-02
Filing date: 2002-07-02
Publication date: 2005-10-12
Anticipated expiration: 2022-07-02
Also published as: JP2004036980A

Description

【０００１】
【発明の属する技術分野】
この発明は、給湯器が、太陽熱等の補助熱源によって生成された予熱温水を利用して給湯を行う給湯システムに関する。
【０００２】
【従来の技術】
補助熱源を利用した給湯システムとしては、例えば、補助熱源である太陽熱を利用して生成された予熱温水を貯留する蓄熱槽を備えている太陽熱利用温水器と、主熱源である給湯器とを組み合わせた給湯システムが従来から一般的に知られている。
【０００３】
こういった、給湯システムでは、太陽熱利用温水器の蓄熱槽と給湯器とが接続されており、出湯時には、太陽熱利用温水器の蓄熱槽に貯留された予熱温水が給湯器に送出されるようになっているが、蓄熱槽から送出される予熱温水をそのままの状態で熱交換器に送出するのではなく、必要に応じて、低温水（常水温の水道水または予熱温水より低い温度の水）を混合した状態で熱交換器に送出することができるように、蓄熱槽から送出される予熱温水と低温水とを任意の混合比率で混合するための混合調節弁が熱交換器の上流側に内蔵された給湯器を使用する場合がある。
【０００４】
また、混合調節弁から熱交換器に温水を送出する、給湯器内のメイン流路には、通常、熱交換器をバイパスするバイパス流路が接続されており、このバイパス流路には、熱交換器によって加熱された高温の温水に、混合調節弁から送出される比較的低温の温水を適宜混合することによって給湯設定温度の温水を生成するためのバイパス弁が設置されている。
【０００５】
こういった混合調節弁が内蔵された給湯器を使用した給湯システムでは、給湯器に対して設定された給湯設定温度以上の予熱温水が蓄熱槽に貯留されている場合は、混合調節弁が、蓄熱槽から送出される給湯設定温度以上の予熱温水と低温水とを適宜混合することによって給湯設定温度の温水を生成し、これを熱交換器に送出することによって、熱交換器を加熱するバーナーを燃焼させることなく、給湯設定温度の温水を出湯することになる。一方、給湯設定温度以上の予熱温水が蓄熱槽に貯留されていない場合は、混合調節弁が、蓄熱槽から送出される給湯設定温度より低い予熱温水を低温水と適宜混合することによって予め定められた固定温度まで下げた状態で熱交換器に送出し、バーナーを燃焼させて熱交換器を加熱することによって、給湯設定温度の温水を生成しながら出湯することになる。
【０００６】
従って、こういった給湯システムでは、給湯器のバーナーを燃焼させることによって給湯設定温度の温水を出湯している状態で、給湯設定温度以上の予熱温水が蓄熱槽から混合調節弁に送出されるようになると、その時点で、混合調節弁が給湯設定温度の温水を生成し始めると共に、バーナーの燃焼停止指令が出力され、給湯器のバーナーの燃焼が停止されることになるが、熱交換器の温度は即座に低下するわけではなく、また、給湯設定温度の温水が即座に熱交換器に送出されるわけではないので、バイパス弁は、バーナーの燃焼が停止した後も、給湯設定温度の温水が引き続き出湯されるように、出湯温度制御を継続し、熱交換器の温度が予め設定された所定温度を下回った時点で、予め設定された固定開度に保持されるようになっている。
【０００７】
【発明が解決しようとする課題】
ところで、バーナーを燃焼させながら給湯設定温度の温水を出湯している状態では、通常、バイパス比率（バイパス流路を通過する温水流量／熱交換器を通過する温水流量）が１．２程度になるように、固定温度及び熱交換器温度が設定されているので、バイパス弁はかなり開いた状態で出湯温度制御を行っているが、給湯器のバーナーが燃焼を停止した後、熱交換器の温度が予め設定された所定温度を下回った時点では、バイパス比率が０．６程度になるように設定されているので、バーナーを燃焼させることなく、給湯設定温度の温水を出湯している状態では、バイパス弁はかなり閉じた状態に保持されている。
【０００８】
このため、バーナーが燃焼を停止している状態における出湯流量が、バーナーが燃焼している状態における出湯流量に比べて低下することになり、例えば、浴槽への自動お湯張りを行うような場合、蓄熱槽に貯留されている予熱温水の温度が給湯設定温度（風呂設定温度）以上である日と、給湯設定温度（風呂設定温度）を下回っている日とでは、自動お湯張りに要する時間が異なるといった問題がある。また、シャワーの使用中にバーナーが燃焼状態から非燃焼状態に切り換わったような場合は、シャワー流量が途中で変動することになるので、良好な使用感を得られないといった問題もある。
【０００９】
そこで、この発明の課題は、バーナーが燃焼していない場合でも、バーナーが燃焼している場合と同程度の出湯流量を確保することができる給湯システムを提供することにある。
【００１０】
【課題を解決するための手段及びその効果】
上記の課題を解決するため、請求項１にかかる発明は、補助熱源によって生成された予熱温水に、必要に応じて低温水を混合しながら給湯器の熱交換器に送出する混合調節弁を備え、前記給湯器は、前記混合調節弁から送出される温水を、前記熱交換器を通して送出するメイン流路と、前記メイン流路における前記熱交換器の前後に接続されたバイパス流路と、前記バイパス流路に設置されたバイパス弁とを備え、前記混合調節弁に送出される前記予熱温水が給湯設定温度以上の場合は、前記熱交換器を加熱することなく、前記混合調節弁が給湯設定温度の温水を生成する給湯設定温度制御を行い、前記混合調節弁に送出される前記予熱温水が給湯設定温度を下回る場合は、前記混合調節弁が、給湯設定温度より低い予め定められた固定温度の温水を生成する固定温度制御を行いながら、前記熱交換器を加熱することによって、給湯設定温度の温水を生成するようになっており、出湯中において、前記熱交換器を加熱している間は、前記バイパス弁が、前記メイン流路から送出される温水の温度が給湯設定温度になるように弁開度を調整する出湯温度制御を行うようになっている給湯システムであって、出湯中において、前記混合調節弁が給湯設定温度制御を行っているときは、前記バイパス弁を、前記熱交換器の加熱を停止する直前における開度または前記熱交換器の加熱中の開度に相当する、予め設定された所定開度に保持するようにしたことを特徴とする給湯システムを提供するものである。
【００１１】
以上のように、この給湯システムでは、混合調節弁が給湯設定温度制御を行っているときは、バイパス弁を、熱交換器の加熱を停止する直前における開度または熱交換器の加熱中の開度に相当する、予め設定された所定開度に保持するようにしたため、バーナーが燃焼を停止している状態における出湯流量が、バーナーが燃焼を行っている状態における出湯流量に比べて低下することがない。
【００１２】
また、上記の課題を解決するため、請求項２にかかる発明は、補助熱源によって生成された予熱温水に、必要に応じて低温水を混合しながら給湯器の熱交換器に送出する混合調節弁を備え、前記給湯器は、前記混合調節弁から送出される温水を、前記熱交換器を通して送出するメイン流路と、前記メイン流路における前記熱交換器の前後に接続されたバイパス流路と、前記バイパス流路に設置されたバイパス弁とを備え、前記混合調節弁に送出される前記予熱温水が給湯設定温度以上の場合は、前記熱交換器を加熱することなく、前記混合調節弁が給湯設定温度の温水を生成する給湯設定温度制御を行い、前記混合調節弁に送出される前記予熱温水が給湯設定温度を下回る場合は、前記混合調節弁が、給湯設定温度より低い予め定められた固定温度の温水を生成する固定温度制御を行いながら、前記熱交換器を加熱することによって、給湯設定温度の温水を生成するようになっており、出湯中において、前記熱交換器を加熱している間は、前記バイパス弁が、前記メイン流路から送出される温水の温度が給湯設定温度になるように弁開度を調整する出湯温度制御を行うようになっている給湯システムであって、前記バイパス弁は、出湯中において、前記熱交換器の加熱を停止した後、前記熱交換器の温度が予め定められた所定温度を下回るまでの間は、前記メイン流路から送出される温水の温度が給湯設定温度になるように弁開度を調整する出湯温度制御を行い、前記熱交換器の温度が予め定められた所定温度を下回った時点で、予め定められた固定開度に保持されるようになっており、出湯中において、前記混合調節弁が固定温度制御から給湯設定温度制御に移行した後、前記混合調節弁から給湯設定温度付近の温水が送出され始めた時点で、前記バイパス弁を、前記熱交換器の加熱を停止する直前における開度または前記熱交換器の加熱中の開度に相当する、予め設定された所定開度に保持するようにしたことを特徴とする給湯システムを提供するものである。
【００１３】
以上のように、この給湯システムでは、出湯中において、混合調節弁が固定温度制御から給湯設定温度制御に切り換わると、即ち、給湯器のバーナーが燃焼状態から非燃焼状態に切り換わると、熱交換器の温度が予め定められた所定温度を下回るまではバイパス弁が出湯温度制御を行い、熱交換器の温度が予め定められた所定温度を下回った時点で、バイパス弁が一旦固定開度に保持された後、混合調節弁から給湯設定温度付近の温水が送出され始めた時点で、バイパス弁が熱交換器の加熱を停止する直前における開度または熱交換器の加熱中の開度に相当する、予め設定された所定開度に保持されるようになっているので、出湯中において、混合調節弁の制御及びバーナーの燃焼状態が切り換わることに伴う出湯温度の変動を最小限に抑えつつ、出湯流量の変動を抑えることができる。
【００１４】
より具体的には、請求項３にかかる発明の給湯システムのように、出湯中において、前記混合調節弁が固定温度制御から給湯設定温度制御に移行した後、前記混合調節弁から送出される温水が、給湯設定温度に対して予め設定された、給湯設定温度より低い所定温度まで昇温した時点で、前記バイパス弁を、前記熱交換器の加熱を停止する直前における開度または前記熱交換器の加熱中の開度に相当する、予め設定された所定開度に保持するようにしておけばよい。
【００１５】
混合調節弁が固定温度制御から給湯設定温度制御に移行した後、混合調節弁から送出される温水の温度は、必ずしも安定しているわけではなく、ハンチングしながら給湯設定温度に収束する場合もあるので、請求項４にかかる発明の給湯システムのように、出湯中において、前記混合調節弁が固定温度制御から給湯設定温度制御に移行した後、前記混合調節弁から送出される温水が、給湯設定温度に対して予め設定された、給湯設定温度より低い所定温度まで昇温した時点から所定時間経過した時点で、前記バイパス弁を、前記熱交換器の加熱を停止する直前における開度または前記熱交換器の加熱中の開度に相当する、予め設定された所定開度に保持するようにしておくことが望ましい。
【００１６】
また、熱交換器内での温水の沸騰を未然に防止するため、熱交換器を加熱するバーナーが燃焼している状態において、熱交換器を通過する温水流量が予め定められた燃焼停止温水流量を下回った時点、または、給湯器からの出湯流量が予め定められた燃焼停止出湯流量を下回った時点で、バーナーが燃焼を停止するようになっている給湯器の場合は、上述したように、混合調節弁が給湯設定温度制御を行っているときに、バイパス弁を、熱交換器の加熱を停止する直前における開度または熱交換器の加熱中の開度に相当する、予め設定された所定開度に保持するようにしておくと、出湯流量が燃焼停止出湯流量を下回る前に、熱交換器を通過する温水流量が燃焼停止温水流量を下回ってしまい、出湯流量が燃焼停止出湯流量を上回っているにも拘わらず、バーナーの燃焼が停止してしまうといった新たな問題が発生するので、請求項５にかかる発明の給湯システムのように、前記バーナーが燃焼している状態において、前記熱交換器を通過する温水流量が燃焼停止温水流量付近まで近づくと、出湯流量が燃焼停止出湯流量を下回る前に、前記熱交換器を通過する温水流量が燃焼停止温水流量を下回らないように、前記バイパス弁の開度を調整するようにしておくことが望ましい。
【００１７】
また、熱交換器内での温水の沸騰を未然に防止するため、熱交換器を加熱するバーナーが燃焼していない状態において、熱交換器を通過する温水流量が予め定められた燃焼開始温水流量以上、かつ、給湯器からの出湯流量が予め定められた燃焼開始出湯流量以上になった時点で、バーナーが燃焼を開始するようになっている給湯器の場合は、上述したように、混合調節弁が給湯設定温度制御を行っているときに、バイパス弁を、熱交換器の加熱を停止する直前における開度または熱交換器の加熱中の開度に相当する、予め設定された所定開度に保持するようにしておくと、出湯流量が燃焼開始出湯流量を上回った後に、熱交換器を通過する温水流量が燃焼開始温水流量を上回ることになり、出湯流量が燃焼開始出湯流量を上回っているにも拘わらず、バーナーが燃焼を開始しないといった新たな問題が発生するので、請求項６にかかる発明の給湯システムのように、前記バーナーが燃焼していない状態において、出湯流量が燃焼開始出湯流量付近まで近づくと、前記熱交換器を通過する温水流量が燃焼開始温水流量以上になる前に、出湯流量が燃焼開始出湯流量以上にならないように、前記バイパス弁の開度を調整するようにしておくことが望ましい。
【００１８】
【発明の実施の形態】
以下、実施の形態について図面を参照して説明する。図１は、補助熱源として太陽熱を利用した給湯システム１の概略構成を示している。この給湯システム１は、同図に示すように、太陽熱利用温水器１０と給湯器２０とが接続されたものであり、太陽熱利用温水器１０によって生成された予熱温水が給湯器２０に送出されるようになっている。
【００１９】
前記太陽熱利用温水器１０は、ソーラー集熱器１１と密閉式の蓄熱槽１４とを備えており、蓄熱槽１４には、その下端部に低温水を供給するための給水管１５が接続されていると共に、上端部には貯留された予熱温水を給湯器２０に送出するための予熱温水供給管１６が接続されている。
【００２０】
前記ソーラー集熱器１１には、その入口側と出口側とを接続するソーラー配管１２によって熱媒体の循環経路が形成されており、このソーラー配管１２は、部分的に蓄熱槽１４内に導入された熱交換部１３を有している。従って、ソーラー集熱器１１によって加熱された熱媒体は、ソーラー配管１２を通って蓄熱槽１４内に導かれ、熱交換部１３で蓄熱槽１４内の水と熱交換を行うことで、蓄熱槽１４内に温水が生成されるようになっている。
【００２１】
前記給湯器２０は、給水管１７を介して供給される低温水と、蓄熱槽１４から予熱温水供給管１６を介して供給される予熱温水とを、必要に応じて混合する混合調節弁２１と、混合調節弁２１の出口側に接続された、混合調節弁２１から送出される温水を必要に応じて加熱する熱交換器２２を有するメイン流路２３と、熱交換器２２をバイパスするように、メイン流路２３に接続されたバイパス流路２４とを備えており、バイパス流路２４には、熱交換器２２から送出される高温の温水に、混合調節弁２１から送出される比較的低温の温水を適宜混合することによって給湯設定温度Ｔｅの温水を生成するためのバイパス弁２４ａが設置されている。
【００２２】
また、給水管１７及び混合調節弁２１の温水出口側に接続されたメイン流路２３には、混合調節弁２１をバイパスするバイパス管２５が接続されており、このバイパス管２５には、通電状態でバイパス管２５の流路を遮断するダイヤフラム方式の電磁弁２５ａが設置されている。
【００２３】
また、混合調節弁２１に接続された予熱温水供給管１６、混合調節弁２１に接続された給水管１７、メイン流路２３におけるバイパス管２５の接続部の上流側及び熱交換器２２とバイパス流路２４の下流側接続部との間には、蓄熱槽１４から送出される予熱温水の温度（以下、予熱温水温度という。）Ｔｐを検出するための予熱温水温度センサ２６ａ、混合調節弁２１に送出される低温水の温度（以下、低温水温度という。）Ｔｗを検出するための低温水温度センサ２６ｂ、混合調節弁２１から送出される温水の温度（以下、混合温水温度という。）Ｔｍを検出するための混合温水温度センサ２７及び熱交換器２２の出口温水温度を、熱交換器２２自体の温度（以下、熱交換器温度という。）Ｔｃとして検出する熱交換器温度センサ２８がそれぞれ設置されており、メイン流路２３には、熱交換器２２とバイパス流路２４の上流側接続部との間に、熱交換器２２を通過する温水の流量を検出するための流量センサ２９が設置されている。
【００２４】
また、給湯器２０には、シリアルインターフェースを介して、操作リモコン３０のコントローラ３０ａとの間で通信可能なコントローラ２０ａが搭載されており、これらのコントローラ２０ａ、３０ａが相互に連携をとりながら、給湯器２０の運転動作を統括的に制御している。
【００２５】
前記コントローラ２０ａには、予熱温水温度センサ２６ａ、低温水温度センサ２６ｂ、混合温水温度センサ２７及び熱交換器温度センサ２８からの温度検出信号や流量センサ２９からの流量検出信号が入力されると共に、操作リモコン３０によって設定された給湯設定温度Ｔｅや運転スイッチ信号等が操作リモコン３０のコントローラ３０ａから送信されるようになっており、これらの温度検出信号及び給湯設定温度Ｔｅ等に基づいて、コントローラ２０ａが混合調節弁２１、バイパス弁２４ａ及び熱交換器２２を加熱するバーナー（図示せず）を制御するようになっている。
【００２６】
蓄熱槽１４から送出される予熱温水の温度、即ち、予熱温水温度センサ２６ａによって検出された予熱温水温度Ｔｐが給湯設定温度Ｔｅ以上の場合は、給湯器２０のバーナーを燃焼させなくても、低温水を適宜混合することによって給湯設定温度Ｔｅの温水を供給することができるので、混合調節弁２１から送出される温水の温度、即ち、混合温水温度センサ２７によって検出される混合温水温度Ｔｍが給湯設定温度Ｔｅになるように、混合調節弁２１の開度を調整する給湯設定温度制御を行うようになっている。
【００２７】
一方、予熱温水温度Ｔｐが給湯設定温度Ｔｅより低い場合は、給湯器２０のバーナーを燃焼させなければ、給湯設定温度Ｔｅの温水を供給することができないので、給湯器２０のバーナーを燃焼させることによって、確実に給湯設定温度Ｔｅの温水を生成することができるように、給湯設定温度Ｔｅ−１０℃（以下、固定温度Ｔｆという）の温水が熱交換器２２に送出されるように、混合調節弁２１の開度を調整して低温水を混合する固定温度制御を行うようになっている。
【００２８】
この場合、給湯器２０のバーナーは、熱交換器温度センサ２８によって検出される熱交換器温度Ｔｃが給湯設定温度Ｔｅ＋１２℃になるように、その燃焼制御を行うようになっているので、バイパス弁２４ａは、熱交換器２２から送出される給湯設定温度Ｔｅ＋１２℃の温水と、バイパス流路２４を通って供給される固定温度Ｔｆの温水とを適宜混合することによって、給湯設定温度Ｔｅの温水を生成することになる。従って、混合調節弁２１が固定温度制御を行うことによって、固定温度Ｔｆの温水を安定して送出している状態では、バイパス比率（バイパス流路２４を通過する温水流量Ｑｂ／熱交換器２２を通過する温水流量（以下、缶体流量という。）Ｑｃ）Ｐが概ね１．２程度になるような弁開度付近で、バイパス弁２４ａの出湯温度制御が行われることになる。
【００２９】
また、出湯が停止されると、バーナーが燃焼していた場合は、その燃焼が停止され、バイパス弁２４ａ及び混合調節弁２１は、それぞれ予め定められた待機位置に保持されることになるが、出湯を開始した時点で、混合調節弁２１が給湯設定温度制御を行うことによって、バーナーを燃焼させることなく、給湯設定温度Ｔｅの温水を出湯することができる場合、即ち、蓄熱槽１４に給湯設定温度Ｔｅ以上の予熱温水が貯留されている場合は、バイパス弁２４ａが、バーナーの燃焼中に出湯温度制御を行っているときの弁開度に相当する、バイパス比率Ｐが概ね１．２程度になるような弁開度に保持されるようになっている。
【００３０】
また、蓄熱槽１４から給湯設定温度Ｔｅを下回る予熱温水が送出されているため、混合調節弁２１が固定温度制御を行いながら、バーナーを燃焼させることによって、給湯設定温度Ｔｅの温水を出湯している状態において、蓄熱槽１４から給湯設定温度Ｔｅ以上の予熱温水が送出されるようになると、混合調節弁２１が給湯設定温度制御に切り換わって、給湯設定温度Ｔｅの温水を生成し始めると共に、バーナーの燃焼停止指令が出力され、給湯器２０のバーナーの燃焼が停止されることになるが、図２に示すように、バーナーの燃焼を停止しても熱交換器温度Ｔｃは即座に低下するわけではないので、バーナーの燃焼が停止された直後は、混合調節弁２１が、即座に給湯設定温度Ｔｅの温水を熱交換器２２に送出するのではなく、熱交換器温度Ｔｃの温度低下に応じて、混合温水温度Ｔｍを徐々に給湯設定温度Ｔｅに近づけるようになっている。
【００３１】
また、出湯中に混合調節弁２１が固定温度制御から給湯設定温度制御に切り換わると、バーナーの燃焼は停止されるが、熱交換器温度Ｔｃが高い間は、熱交換器２２の予熱が出湯温度に影響を及ぼすおそれがあるので、同図に示すように、バイパス弁２４ａは、熱交換器温度Ｔｃが給湯設定温度Ｔｅ＋５℃以下になるまでは、上述した出湯温度制御を継続することによって、出湯温度の変動を極力防止し、熱交換器温度Ｔｃが給湯設定温度Ｔｅ＋５℃になった時点で、バイパス比率Ｐが０．６程度になるような固定開度に保持されるようになっている。
【００３２】
その後、混合調節弁２１から送出される温水の温度（混合温水温度Ｔｍ）が、給湯設定温度Ｔｅ−１℃まで上昇すると、その時点から所定時間（例えば、５秒）を経過した時点で、バイパス弁２４ａは、上述した固定開度から、バーナーの燃焼中に出湯温度制御を行っていたときの弁開度に相当する、バイパス比率Ｐが概ね１．２程度になるような所定開度まで開き、その状態で保持されるようになっている。
【００３３】
以上のように、この給湯システム１では、混合調節弁２１が給湯設定温度制御を行っているとき、即ち、バーナーが燃焼することなく、給湯設定温度Ｔｅの温水を出湯しているときは、バイパス弁２４ａが、バーナーの燃焼中に出湯温度制御を行っているときの弁開度に相当する、予め定められた所定開度に保持されるようになっているので、バーナーが燃焼していないときの出湯流量が、バーナーが燃焼しているときの出湯流量に比べて低下することがない。従って、従来の給湯システムのように、蓄熱槽に給湯設定温度（風呂設定温度）以上の予熱温水が貯留されている日と、給湯設定温度（風呂設定温度）を下回る予熱温水が貯留されている日とで、自動お湯張りに要する時間が異なることがなく、補助熱源によって生成された予熱温水を利用しない通常の給湯システムと同様の使用感を得ることができる。
【００３４】
特に、出湯中に混合調節弁２１が固定温度制御から給湯設定温度制御に切り換わった場合、即ち、出湯中に給湯器２０のバーナーが燃焼状態から非燃焼状態に切り換わった場合は、出湯温度が変動しないように、熱交換器温度Ｔｃが給湯設定温度Ｔｅ＋５℃を下回るまではバイパス弁２４ａが出湯温度制御を継続すると共に、熱交換器温度Ｔｃの低下に応じて、混合調節弁２１が混合温水温度Ｔｍを給湯設定温度Ｔｅまで徐々に昇温させ、混合温水温度Ｔｍが給湯設定温度Ｔｅ−１℃まで上昇した時点から所定時間（５秒）が経過した時点で、バイパス弁２４ａを、バーナーの燃焼中に出湯温度制御を行っているときの弁開度に相当する、予め定められた所定開度に保持することによって、出湯流量の低下を防止するようにしているので、出湯中において、混合調節弁２１の制御及びバーナーの燃焼状態が切り換わることに伴う出湯温度の変動を最小限に抑えつつ、出湯流量の変動を抑えることができる。従って、シャワーの使用中にバーナーが燃焼状態から非燃焼状態に切り換わったような場合でも、出湯温度や出湯流量が途中で極端に変動することがなく、良好な使用感を得ることができる。
【００３５】
また、バーナーが燃焼している状態において、ある程度の出湯流量Ｑｔが確保されていても、何らかの理由によって、缶体流量Ｑｃが極端に低下している場合には、熱交換器２２を通過する温水が沸騰してしまうので、こういった沸騰状態の発生を未然に防止するため、この給湯器２０では、給湯器２０のバーナーが燃焼している状態において、給湯器２０からの出湯流量Ｑｔまたは缶体流量Ｑｃのいずれか一方が、燃焼停止出湯流量（２．０ｌ／ｍｉｎ）Ｑｔｆまたは燃焼停止缶体流量（１．３ｌ／ｍｉｎ）Ｑｃｆを下回ると、バーナーが燃焼を停止するようになっており、給湯器２０のバーナーが燃焼していない状態では、缶体流量Ｑｃ及び出湯流量Ｑｔの双方が、それぞれ燃焼開始缶体流量（２．０ｌ／ｍｉｎ）Ｑｃｎ以上及び燃焼開始出湯流量（３．０ｌ／ｍｉｎ）Ｑｔｎ以上にならなければ、バーナーが燃焼を開始しないようになっている。
【００３６】
なお、図３では、缶体流量Ｑｃが燃焼停止缶体流量Ｑｃｆ及び燃焼開始缶体流量Ｑｃｎのときの出湯流量Ｑｔとバイパス比率Ｐとの関係が一点鎖線及び二点鎖線でそれぞれ示されているので、同図において、斜線で示す領域がバーナーの燃焼停止領域、交斜線で示す領域がバーナーの燃焼開始領域となり、燃焼停止領域の外側から燃焼停止領域に進入した時点でバーナーの燃焼が停止され、燃焼開始領域の外側から燃焼開始領域に進入した時点でバーナーの燃焼が開始されることになる。また、この給湯システム１では、缶体流量Ｑｃを流量センサ２９によって実測しているだけなので、出湯流量Ｑｔについては、実測された缶体流量Ｑｃ、熱交換器温度Ｔｃ、混合温水温度Ｔｍ及び低温水温度Ｔｗから、数１に示す演算式に従って算出している。
【００３７】
【数１】

【００３８】
ところで、この給湯システム１では、上述したように、出湯中は、バーナーが燃焼状態であるか、非燃焼状態であるかに拘わらず、バイパス比率Ｐが概ね１．２程度になるように、バイパス弁２４ａの開度が保持されるようになっているので、図４（ａ）に示すように、出湯中に出湯流量Ｑｔが徐々に低下してくると、出湯流量Ｑｔが燃焼停止出湯流量Ｑｔｆを下回る前に、缶体流量Ｑｃが燃焼停止缶体流量Ｑｃｆを下回ってしまい、出湯流量Ｑｔが燃焼停止出湯流量Ｑｔｆを上回っているにも拘わらず、バーナーの燃焼が停止してしまうことになる。また、出湯を開始した後、出湯流量Ｑｔが徐々に上昇する場合は、同図（ｂ）に示すように、缶体流量Ｑｃが燃焼開始缶体流量Ｑｃｎを上回る前に、出湯流量Ｑｔが燃焼開始出湯流量Ｑｔｎを上回ってしまい、出湯流量Ｑｔが燃焼開始出湯流量Ｑｔｎを上回っているにも拘わらず、バーナーの燃焼が開始されないといった問題が発生する。
【００３９】
そこで、この給湯システム１では、バーナーが燃焼している状態において、缶体流量Ｑｃが燃焼停止缶体流量Ｑｃｆ付近まで近づくと、出湯流量Ｑｔが燃焼停止出湯流量Ｑｔｆを下回る前に、缶体流量Ｑｃが燃焼停止缶体流量Ｑｃｆを下回らないように、出湯流量Ｑｔに応じてバイパス弁２４ａの最大開度（最大バイパス比率Ｐｍａｘ）を制限するようになっており、バーナーが燃焼していない状態において、出湯流量Ｑｔが燃焼開始出湯流量Ｑｔｎ付近まで近づくと、缶体流量Ｑｃが燃焼開始缶体流量Ｑｃｎ以上になる前に、出湯流量Ｑｔが燃焼開始出湯流量Ｑｔｎ以上にならないように、出湯流量Ｑｔに応じてバイパス弁２４ａの最大開度（最大バイパス比率Ｐｍａｘ）を制限するようになっている。
【００４０】
即ち、バーナーが燃焼している状態において、出湯流量Ｑｔが低下してくる場合は、数２に示す演算式に従って、そのときの出湯流量Ｑｔにおける最大バイパス比率Ｐｍａｘを算出し、その算出された最大バイパス比率Ｐｍａｘを上回らないように、バイパス弁２４ａの最大開度を制限するようになっており、バーナーが燃焼していない状態において、出湯流量Ｑｔが上昇していく場合は、数３に示す演算式に従って、そのときの出湯流量Ｑｔにおける最大バイパス比率Ｐｍａｘを算出し、その算出された最大バイパス比率Ｐｍａｘを上回らないように、バイパス弁２４ａの最大開度を制限するようになっている。なお、図５には、数２及び数３に示す演算式に従って算出された出湯流量Ｑｔに対する最大バイパス比率Ｐｍａｘを実線及び破線でそれぞれ示している。
【００４１】
【数２】

【００４２】
【数３】

【００４３】
従って、この給湯システム１では、バーナーが燃焼しながら出湯を行っている状態では、図６（ａ）に斜線で示す領域内において、出湯流量Ｑｔが低下していくことになるので、出湯流量Ｑｔが燃焼停止出湯流量Ｑｔｆを下回った後に、缶体流量Ｑｃが燃焼停止缶体流量Ｑｃｆを下回ることになり、出湯流量Ｑｔが燃焼停止出湯流量Ｑｔｆを下回った時点で確実にバーナーの燃焼が停止されることになる。
【００４４】
また、バーナーが燃焼していない状態では、同図（ｂ）に斜線で示す領域内において、出湯流量Ｑｔが上昇していくことになるので、缶体流量Ｑｃが燃焼開始缶体流量Ｑｃｎを上回った後に、出湯流量Ｑｔが燃焼開始出湯流量Ｑｔｎを上回ることになり、出湯流量Ｑｔが燃焼開始出湯流量Ｑｔｎを上回った時点で確実にバーナーの燃焼が開始されることになる。
【００４５】
以上のように、この給湯システム１では、出湯流量Ｑｔが小流量域に入ってくると、最大バイパス比率Ｐｍａｘが制限されることになるので、バイパス弁２４ａが出湯温度制御を確実に行うことができず、出湯温度が一時的に乱れることになるが、こういった小流量域で出湯を行うことはほとんどないので、特に、問題になることはない。
【００４６】
なお、上述した実施形態では、出湯中に混合調節弁２１が固定温度制御から給湯設定温度制御に切り換わると、混合調節弁２１から送出される温水の温度（混合温水温度Ｔｍ）が給湯設定温度Ｔｅ−１℃まで上昇した時点から、所定時間（例えば、５秒）が経過した時点で、バイパス弁２４ａを、バーナーの燃焼中に出湯温度制御を行っていたときの弁開度に相当する所定開度に保持するようになっているが、これに限定されるものではなく、混合温水温度Ｔｍが給湯設定温度Ｔｅ−１℃まで上昇した時点で、バイパス弁２４ａを所定開度に保持したり、混合温水温度Ｔｍが給湯設定温度Ｔｅを中心とした所定の温度範囲（例えば、給湯設定温度Ｔｅ±１℃）内で安定した時点で、バイパス弁２４ａを所定開度に保持することも可能である。
【００４７】
また、上述した実施形態では、出湯中に混合調節弁２１が固定温度制御から給湯設定温度制御に切り換わると、バイパス弁２４ａを、バーナーの燃焼中に出湯温度制御を行っていたときの弁開度に相当する、予め定められた所定開度（上述した実施形態の場合は、バイパス比率Ｐが１．２程度になるような弁開度）に保持するようになっているが、これに限定されるものではなく、バーナーの燃焼を停止する直前の弁開度を記憶しておき、その弁開度に保持することも可能である。
【００４８】
また、上述した実施形態では、混合調節弁２１が固定温度制御を行う場合の目標温度である固定温度Ｔｆを、給湯設定温度Ｔｅ−１０℃に設定しているが、これに限定されるものではなく、例えば、給湯設定温度Ｔｅが６０℃以上、６０℃未満３５℃以上、３５℃未満に場合分けし、６０℃以上の場合は４５℃、６０℃未満３５℃以上の場合は３０℃、３５℃未満の場合は２５℃といった具合に、給湯設定温度Ｔｅに応じて、固定温度Ｔｆを段階的に設定することも可能である。ただし、その場合は、設定された固定温度Ｔｆに応じて、バーナーの燃焼を停止したときに保持すべきバイパス比率Ｐを算出し、そのバイパス比率Ｐになるような弁開度にバイパス弁２４ａの開度を保持する必要がある。
【００４９】
また、上述した実施形態では、混合調節弁２１が組み込まれた給湯器２０を使用した給湯システムについて説明したが、これに限定されるものではなく、混合調節弁を有する給湯接続ユニットを介して、太陽熱利用温水器と通常の給湯器とを接続した給湯システムについても、本発明を適用することができることはいうまでもない。
【００５０】
また、上述した実施形態では、補助熱源が太陽熱である給湯システムについて説明したが、補助熱源はこういった太陽熱に限定されるものではなく、例えば、コージェネレーションシステムにおけるガスエンジンやガスタービンの排熱を補助熱源とした給湯システムのように、種々の補助熱源を使用した給湯システムについて、本発明を適用することができることはいうまでもない。
【図面の簡単な説明】
【図１】この発明にかかる給湯システムの一実施形態を示す概略構成図である。
【図２】同上の給湯システムにおいて、出湯中に混合調節弁が固定温度制御から給湯設定温度制御に切り換わった時点における運転状態を示す図である。
【図３】同上の給湯システムに使用されている給湯器におけるバーナーの燃焼停止タイミング及び燃焼開始タイミングを説明するための説明図である。
【図４】（ａ）、（ｂ）はバーナーの燃焼停止時に保持するバイパス弁の開度を、バーナーの燃焼中におけるバイパス弁の開度に相当する所定開度に設定した場合の問題点を説明するための説明図である。
【図５】同上の問題点を解決するための手法を説明するための説明図である。
【図６】（ａ）は同上の手法を採用した場合のバーナーの燃焼停止タイミングを説明するための説明図、（ｂ）は同上の手法を採用した場合のバーナーの燃焼開始タイミングを説明するための説明図である。
【符号の説明】
１給湯システム
１０太陽熱利用温水器
１４蓄熱槽
１５、１７給水管
１６予熱温水供給管
２０給湯器
２０ａコントローラ
２１混合調節弁
２２熱交換器
２３メイン流路
２４バイパス流路
２４ａバイパス弁
２５バイパス管
２５ａ電磁弁
２６ａ予熱温水温度センサ
２６ｂ低温水温度センサ
２７混合温水温度センサ
２８熱交換器温度センサ
２９流量センサ
３０操作リモコン
３０ａコントローラ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hot water supply system in which a hot water heater supplies hot water using preheated hot water generated by an auxiliary heat source such as solar heat.
[0002]
[Prior art]
As a hot water supply system using an auxiliary heat source, for example, a solar water heater having a heat storage tank for storing preheated hot water generated using solar heat as an auxiliary heat source and a hot water heater as a main heat source are combined. Conventional hot water supply systems are generally known.
[0003]
In such a hot water supply system, the heat storage tank of the solar water heater is connected to the water heater, and the preheated hot water stored in the heat storage tank of the solar water heater is sent to the water heater at the time of hot water. However, instead of sending the preheated hot water sent from the heat storage tank to the heat exchanger as it is, low-temperature water (water with a lower temperature than normal-temperature tap water or preheated hot water) as needed The mixing control valve for mixing the preheated hot water and low temperature water sent from the heat storage tank at an arbitrary mixing ratio is provided upstream of the heat exchanger so that it can be sent to the heat exchanger in a mixed state. A built-in water heater may be used.
[0004]
In addition, a bypass channel that bypasses the heat exchanger is usually connected to the main channel in the water heater that sends hot water from the mixing control valve to the heat exchanger. A bypass valve for generating hot water having a hot water supply set temperature by appropriately mixing hot water heated by the exchanger with hot water having a relatively low temperature delivered from the mixing control valve is installed.
[0005]
In a hot water supply system using a water heater with a built-in mixing control valve, when preheated hot water that is higher than the hot water set temperature set for the water heater is stored in the heat storage tank, the mixing control valve is Burner that heats the heat exchanger by generating hot water at a hot water supply set temperature by appropriately mixing preheated hot water that is higher than the hot water set temperature sent from the heat storage tank and low temperature water and sending it to the heat exchanger The hot water at the hot water supply set temperature is discharged without burning the water. On the other hand, when preheated hot water equal to or higher than the hot water supply set temperature is not stored in the heat storage tank, the mixing control valve is determined in advance by appropriately mixing preheated hot water lower than the hot water supply set temperature sent from the heat storage tank with low temperature water. When the temperature is lowered to the fixed temperature, the heat is sent to the heat exchanger, the burner is burned to heat the heat exchanger, and hot water is discharged while generating hot water at the hot water supply set temperature.
[0006]
Therefore, in such a hot water supply system, preheated hot water at or above the hot water supply set temperature is sent from the heat storage tank to the mixing control valve in a state where hot water at the hot water supply set temperature is discharged by burning the burner of the water heater. At that time, the mixing control valve starts to generate hot water at the hot water supply set temperature, and a burner combustion stop command is output to stop the combustion of the water heater burner. Since the temperature does not decrease immediately and the hot water at the hot water supply set temperature is not immediately sent to the heat exchanger, the bypass valve remains hot water at the hot water supply set temperature even after combustion of the burner stops. The hot water temperature control is continued so that the hot water is continuously discharged, and when the temperature of the heat exchanger falls below a predetermined temperature, the fixed opening degree is set in advance. .
[0007]
[Problems to be solved by the invention]
By the way, in the state where hot water of the hot water supply set temperature is discharged while burning the burner, the bypass ratio (the flow rate of hot water passing through the bypass channel / the flow rate of hot water passing through the heat exchanger) is usually about 1.2. As shown in the figure, the fixed temperature and the heat exchanger temperature are set, so the hot water temperature control is performed with the bypass valve being quite open, but after the water heater burner stops combustion, the temperature of the heat exchanger When the temperature falls below the preset predetermined temperature, the bypass ratio is set to be about 0.6, so in the state where hot water at the hot water supply set temperature is discharged without burning the burner, The bypass valve is kept fairly closed.
[0008]
For this reason, the hot water flow rate in a state where the burner stops combustion will be lower than the hot water flow rate in a state where the burner is burning, for example, when performing automatic hot water filling to the bathtub, The time required for automatic hot water filling differs between the day when the temperature of the preheated hot water stored in the heat storage tank is higher than the hot water supply set temperature (bath set temperature) and the day when it is below the hot water set temperature (bath set temperature). There is a problem. In addition, when the burner is switched from the combustion state to the non-combustion state during use of the shower, there is a problem in that a good feeling of use cannot be obtained because the shower flow rate fluctuates in the middle.
[0009]
Then, the subject of this invention is providing the hot water supply system which can ensure the hot water flow rate comparable as the case where the burner is burning, even when the burner is not burning.
[0010]
[Means for solving the problems and effects thereof]
In order to solve the above-mentioned problem, the invention according to claim 1 includes a mixing control valve for feeding the preheated hot water generated by the auxiliary heat source to the heat exchanger of the water heater while mixing low temperature water as necessary. The hot water supply device is a main flow path for sending hot water sent from the mixing control valve through the heat exchanger, a bypass flow path connected before and after the heat exchanger in the main flow path, And when the preheated hot water sent to the mixing control valve is equal to or higher than a hot water supply set temperature, the mixing control valve is set to hot water without heating the heat exchanger. Hot water set temperature control for generating hot water of temperature is performed, and when the preheated hot water sent to the mixing control valve is lower than the hot water set temperature, the mixing control valve is set at a predetermined fixed temperature lower than the hot water set temperature. While performing the fixed temperature control for generating hot water, heating the heat exchanger generates hot water at a hot water supply set temperature, and while heating the heat exchanger in the hot water, The bypass valve is a hot water supply system configured to perform a hot water temperature control for adjusting a valve opening degree so that a temperature of hot water sent from the main flow path becomes a hot water supply set temperature. When the mixing control valve performs hot water set temperature control, the bypass valve is Opening just before stopping heating of the heat exchanger or It is intended to provide a hot water supply system characterized in that the heat exchanger is held at a predetermined opening degree corresponding to the opening degree during heating of the heat exchanger.
[0011]
As described above, in this hot water supply system, when the mixing control valve performs the hot water supply set temperature control, the bypass valve is Opening just before stopping heat exchanger heating or Since the heat exchanger is kept at a predetermined opening degree that corresponds to the opening degree during heating, the outlet water flow rate in a state where the burner stops combustion is in the state where the burner is burning. There is no drop compared to the hot water flow rate.
[0012]
In order to solve the above-mentioned problem, the invention according to claim 2 is a mixing control valve for sending to a heat exchanger of a water heater while mixing low-temperature water as necessary with preheated hot water generated by an auxiliary heat source. The water heater includes a main flow path for sending hot water sent from the mixing control valve through the heat exchanger, and a bypass flow path connected before and after the heat exchanger in the main flow path. And when the preheated hot water sent to the mixing control valve is equal to or higher than a hot water supply set temperature, the mixing control valve is not heated without heating the heat exchanger. Hot water supply set temperature control for generating hot water at a hot water supply set temperature is performed, and when the preheated hot water sent to the mixing control valve is lower than the hot water supply set temperature, the mixing control valve is predetermined lower than the hot water supply set temperature. Solid While performing the fixed temperature control for generating hot water of temperature, heating of the heat exchanger generates hot water of a hot water supply set temperature, and the heat exchanger is heated in the hot water. The hot water supply system in which the bypass valve performs hot water temperature control for adjusting the valve opening so that the temperature of the hot water sent from the main flow path becomes the hot water supply set temperature, The bypass valve, during the hot water, after the heating of the heat exchanger is stopped, until the temperature of the heat exchanger falls below a predetermined temperature, the temperature of the hot water sent from the main flow path The hot water temperature control is performed to adjust the valve opening so that the temperature becomes the hot water supply set temperature, and when the temperature of the heat exchanger falls below a predetermined temperature, it is held at a predetermined fixed opening. Like During the hot water supply, when the mixing control valve shifts from the fixed temperature control to the hot water supply set temperature control, when the hot water near the hot water supply set temperature starts to be sent from the mixing control valve, the bypass valve is Provided is a hot water supply system which is maintained at a predetermined opening degree corresponding to the opening degree immediately before stopping the heating of the exchanger or the opening degree during heating of the heat exchanger. It is.
[0013]
As described above, in this hot water supply system, when the mixing control valve is switched from the fixed temperature control to the hot water supply set temperature control in the hot water, that is, when the burner of the hot water heater is switched from the combustion state to the non-combustion state, The bypass valve performs tapping temperature control until the temperature of the exchanger falls below a predetermined temperature, and when the temperature of the heat exchanger falls below a predetermined temperature, the bypass valve temporarily reaches a fixed opening. After being held, when the hot water near the hot water supply set temperature starts to be sent from the mixing control valve, it corresponds to the opening just before the bypass valve stops heating the heat exchanger or the opening during heating of the heat exchanger In order to minimize the fluctuations in the temperature of the hot water as the mixing control valve is controlled and the combustion state of the burner is switched during the hot water. One, it is possible to suppress the fluctuation of the hot water flow rate.
[0014]
More specifically, as in the hot water supply system according to the third aspect of the present invention, in the hot water, the hot water supplied from the mixing control valve after the mixing control valve has shifted from the fixed temperature control to the hot water supply set temperature control. However, when the temperature is raised to a predetermined temperature lower than the hot water supply set temperature, which is preset with respect to the hot water supply set temperature, the opening degree immediately before the heating of the heat exchanger is stopped or the heat exchanger What is necessary is just to make it hold | maintain at the predetermined opening degree preset corresponding to the opening degree during heating.
[0015]
After the mixing control valve shifts from the fixed temperature control to the hot water supply set temperature control, the temperature of the hot water sent from the mixing control valve is not necessarily stable and may converge to the hot water supply set temperature while hunting. Therefore, as in the hot water supply system of the invention according to claim 4, after the mixing control valve shifts from the fixed temperature control to the hot water supply set temperature control in the hot water, the hot water sent from the mixing control valve is set to the hot water supply setting. When the predetermined time elapses from the time when the temperature is raised to a predetermined temperature lower than the hot water supply set temperature, which is preset with respect to the temperature, the degree of opening or the heat immediately before the heating of the heat exchanger is stopped. It is desirable to maintain a predetermined opening that corresponds to the opening of the exchanger during heating.
[0016]
Also, in order to prevent boiling of hot water in the heat exchanger, the flow rate of hot water passing through the heat exchanger is determined in advance when the burner that heats the heat exchanger is burning. In the case of a water heater in which the burner is configured to stop combustion when the temperature falls below or when the flow rate of hot water from the water heater falls below a predetermined combustion stop hot water flow rate, as described above, When the mixing control valve performs the hot water supply set temperature control, the bypass valve is set to a predetermined value corresponding to the opening degree immediately before stopping the heating of the heat exchanger or the opening degree during heating of the heat exchanger. If the opening is kept at the opening, the hot water flow rate passing through the heat exchanger will be lower than the combustion stop warm water flow rate before the hot water flow rate falls below the combustion stop hot water flow rate, and the hot water flow rate will exceed the combustion stop hot water flow rate. While Regardless, a new problem that combustion of the burner stops occurs, so that the heat exchanger passes through the heat exchanger in a state where the burner is burning as in the hot water supply system of the invention according to claim 5. When the hot water flow rate approaches the combustion stop hot water flow rate, the opening degree of the bypass valve is set so that the hot water flow rate passing through the heat exchanger does not fall below the combustion stop hot water flow rate before the hot water flow rate falls below the combustion stop hot water flow rate. It is desirable to adjust this.
[0017]
Also, in order to prevent boiling of hot water in the heat exchanger, the flow rate of hot water passing through the heat exchanger is determined in advance when the burner that heats the heat exchanger is not combusting. In the case of the hot water heater in which the burner starts to combust when the hot water flow rate from the water heater becomes equal to or higher than the predetermined combustion start hot water flow rate, the mixing adjustment is performed as described above. When the valve is performing hot water supply set temperature control, the bypass valve is set to a predetermined opening degree that corresponds to the opening degree immediately before stopping the heat exchanger heating or the opening degree during heating of the heat exchanger. If the hot water flow rate exceeds the combustion start hot water flow rate, the hot water flow rate passing through the heat exchanger will exceed the combustion start hot water flow rate, and the hot water flow rate will exceed the combustion start hot water flow rate. I am also Thus, a new problem that the burner does not start combustion occurs. Therefore, in the state where the burner is not combusting as in the hot water supply system of the invention according to claim 6, the hot water flow rate is close to the combustion start hot water flow rate. When approaching, the opening degree of the bypass valve should be adjusted so that the hot water flow rate does not exceed the combustion start hot water flow rate before the hot water flow rate passing through the heat exchanger becomes equal to or higher than the combustion start hot water flow rate. Is desirable.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a hot water supply system 1 using solar heat as an auxiliary heat source. In this hot water supply system 1, as shown in the figure, a solar water heater 10 and a hot water heater 20 are connected, and preheated hot water generated by the solar water heater 10 is sent to the water heater 20. It is like that.
[0019]
The solar-heated water heater 10 includes a solar heat collector 11 and a sealed heat storage tank 14, and a water supply pipe 15 for supplying low-temperature water to the lower end of the heat storage tank 14 is connected to the heat storage tank 14. At the same time, a preheated hot water supply pipe 16 for sending the stored preheated hot water to the water heater 20 is connected to the upper end.
[0020]
In the solar collector 11, a heat medium circulation path is formed by a solar pipe 12 that connects the inlet side and the outlet side of the solar collector 11, and the solar pipe 12 is partially introduced into the heat storage tank 14. The heat exchanger 13 is provided. Therefore, the heat medium heated by the solar heat collector 11 is guided into the heat storage tank 14 through the solar pipe 12, and heat exchange with the water in the heat storage tank 14 is performed by the heat exchanging unit 13, thereby the heat storage tank. Hot water is generated in 14.
[0021]
The water heater 20 includes a mixing control valve 21 that mixes low temperature water supplied via the water supply pipe 17 and preheated hot water supplied from the heat storage tank 14 via the preheated hot water supply pipe 16 as necessary. The main flow path 23 having the heat exchanger 22 connected to the outlet side of the mixing control valve 21 and heating the hot water delivered from the mixing control valve 21 as necessary is bypassed. And a bypass channel 24 connected to the main channel 23. The bypass channel 24 has a relatively low temperature delivered from the mixing control valve 21 to the hot water delivered from the heat exchanger 22. A bypass valve 24a for generating hot water having a hot water supply set temperature Te by appropriately mixing the hot water is provided.
[0022]
In addition, a bypass pipe 25 that bypasses the mixing control valve 21 is connected to the main flow path 23 connected to the hot water outlet side of the water supply pipe 17 and the mixing control valve 21, and the bypass pipe 25 is energized. A diaphragm type electromagnetic valve 25a for blocking the flow path of the bypass pipe 25 is installed.
[0023]
Further, the preheated hot water supply pipe 16 connected to the mixing control valve 21, the water supply pipe 17 connected to the mixing control valve 21, the upstream side of the connection portion of the bypass pipe 25 in the main flow path 23, and the heat exchanger 22 and the bypass flow Between the downstream connection portion of the passage 24, a preheated hot water temperature sensor 26a for detecting the temperature of preheated hot water sent from the heat storage tank 14 (hereinafter referred to as preheated hot water temperature) Tp, and the mixing control valve 21 are connected. The temperature of the low-temperature water sent (hereinafter referred to as the low-temperature water temperature) Tw for detecting the low-temperature water temperature sensor 26b for detecting the temperature Tw and the temperature of the hot water sent from the mixing control valve 21 (hereinafter referred to as the mixed hot-water temperature) Tm. A heat exchanger temperature sensor 28 for detecting the mixed hot water temperature sensor 27 for detection and the outlet hot water temperature of the heat exchanger 22 as the temperature of the heat exchanger 22 itself (hereinafter referred to as heat exchanger temperature) Tc. A flow rate sensor for detecting the flow rate of hot water passing through the heat exchanger 22 between the heat exchanger 22 and the upstream connection portion of the bypass flow channel 24 in the main flow channel 23. 29 is installed.
[0024]
Further, the water heater 20 is equipped with a controller 20a capable of communicating with the controller 30a of the operation remote controller 30 via a serial interface, and these

controllers

20a and 30a cooperate with each other to supply hot water. The operation of the vessel 20 is comprehensively controlled.
[0025]
The controller 20a receives a temperature detection signal from the preheated hot water temperature sensor 26a, a low temperature water temperature sensor 26b, a mixed hot water temperature sensor 27, and a heat exchanger temperature sensor 28 and a flow rate detection signal from the flow rate sensor 29, A hot water supply set temperature Te, an operation switch signal, and the like set by the operation remote controller 30 are transmitted from the controller 30a of the operation remote controller 30, and the controller 20a is based on these temperature detection signals, the hot water supply set temperature Te, and the like. Controls a burner (not shown) for heating the mixing control valve 21, the bypass valve 24a and the heat exchanger 22.
[0026]
If the temperature of the preheated hot water delivered from the heat storage tank 14, that is, the preheated hot water temperature Tp detected by the preheated hot water temperature sensor 26a is equal to or higher than the hot water supply set temperature Te, the temperature of the hot water heater 20 can be reduced without burning. Since hot water having a hot water supply set temperature Te can be supplied by appropriately mixing water, the temperature of the hot water sent from the mixing control valve 21, that is, the mixed hot water temperature Tm detected by the mixed hot water temperature sensor 27 is used. Hot water supply set temperature control is performed to adjust the opening of the mixing control valve 21 so that the set temperature Te is reached.
[0027]
On the other hand, when the preheated hot water temperature Tp is lower than the hot water supply set temperature Te, the hot water at the hot water supply set temperature Te cannot be supplied unless the burner in the hot water heater 20 is burned. Is adjusted so that hot water at a hot water supply set temperature Te-10 ° C. (hereinafter referred to as a fixed temperature Tf) is sent to the heat exchanger 22 so that hot water at a hot water supply set temperature Te can be reliably generated. The fixed temperature control which adjusts the opening degree of the valve 21 and mixes low temperature water is performed.
[0028]
In this case, the burner of the water heater 20 performs the combustion control so that the heat exchanger temperature Tc detected by the heat exchanger temperature sensor 28 becomes the hot water supply set temperature Te + 12 ° C. Therefore, the bypass valve 24a mixes hot water at a hot water supply set temperature Te + 12 ° C. sent from the heat exchanger 22 and hot water at a fixed temperature Tf supplied through the bypass flow path 24, so that hot water at the hot water supply set temperature Te is mixed. Will be generated. Therefore, when the mixing control valve 21 performs the fixed temperature control, the hot water having the fixed temperature Tf is stably sent out, so that the bypass ratio (the hot water flow rate Qb passing through the bypass flow path 24 / the heat exchanger 22 is changed). The hot water flow rate of the bypass valve 24a is controlled in the vicinity of the valve opening so that the passing hot water flow rate (hereinafter referred to as the can flow rate) Qc) P is about 1.2.
[0029]
Further, when the hot water is stopped, if the burner is burning, the combustion is stopped, and the bypass valve 24a and the mixing control valve 21 are respectively held at predetermined standby positions. When hot water is started, the mixing control valve 21 performs hot water supply set temperature control so that hot water at the hot water supply set temperature Te can be discharged without burning the burner, that is, hot water is set in the heat storage tank 14. When preheated hot water of temperature Te or higher is stored, the bypass ratio P, which corresponds to the valve opening degree when the bypass valve 24a performs hot water temperature control during combustion of the burner, is approximately 1.2. It is held at such a valve opening.
[0030]
In addition, since preheated hot water that is lower than the hot water supply set temperature Te is sent from the heat storage tank 14, the mixing control valve 21 performs the fixed temperature control and burns the burner to discharge hot water at the hot water supply set temperature Te. When the preheated hot water of the hot water supply set temperature Te or higher is sent from the heat storage tank 14 in the state, the mixing control valve 21 is switched to the hot water supply set temperature control, and starts generating hot water of the hot water supply set temperature Te. A burner combustion stop command is output and combustion of the burner of the water heater 20 is stopped. However, as shown in FIG. 2, even if the burner combustion is stopped, the heat exchanger temperature Tc immediately decreases. Therefore, immediately after the combustion of the burner is stopped, the mixing control valve 21 does not immediately send the hot water of the hot water supply set temperature Te to the heat exchanger 22, but the heat exchanger. Depending on the temperature drop in degrees Tc, which is a mixture heated temperature Tm gradually closer to the hot water set temperature Te.
[0031]
Further, when the mixing control valve 21 is switched from fixed temperature control to hot water supply set temperature control during tapping, the combustion of the burner is stopped, but preheating of the heat exchanger 22 is performed while the heat exchanger temperature Tc is high. Since there is a possibility of affecting the temperature, as shown in the figure, the bypass valve 24a continues the above-described hot water temperature control until the heat exchanger temperature Tc becomes equal to or lower than the hot water supply set temperature Te + 5 ° C. Fluctuation of the hot water temperature is prevented as much as possible, and when the heat exchanger temperature Tc reaches the hot water supply set temperature Te + 5 ° C., the fixed opening degree is maintained such that the bypass ratio P is about 0.6. .
[0032]
Thereafter, when the temperature of the hot water sent from the mixing control valve 21 (mixed hot water temperature Tm) rises to the hot water supply set temperature Te-1 ° C., the bypass is performed when a predetermined time (for example, 5 seconds) elapses from that point. The valve 24a opens from the above-described fixed opening degree to a predetermined opening degree corresponding to the valve opening degree when the hot water temperature control is performed during combustion of the burner so that the bypass ratio P is about 1.2. , Is to be held in that state.
[0033]
As described above, in the hot water supply system 1, when the mixing control valve 21 performs the hot water supply set temperature control, that is, when the hot water at the hot water supply set temperature Te is discharged without burning the burner, When the burner is not combusting because the valve 24a is held at a predetermined opening that corresponds to the valve opening when the hot water temperature control is performed during combustion of the burner. The hot water flow rate is not reduced compared with the hot water flow rate when the burner is burning. Therefore, as in the conventional hot water supply system, the day when preheated hot water equal to or higher than the hot water supply set temperature (bath set temperature) is stored in the heat storage tank, and the preheat hot water below the hot water set temperature (bath set temperature) is stored. The time required for automatic hot water filling does not differ from day to day, and a feeling of use similar to that of a normal hot water supply system that does not use preheated hot water generated by an auxiliary heat source can be obtained.
[0034]
In particular, when the mixing control valve 21 is switched from the fixed temperature control to the hot water supply set temperature control during the hot water, that is, when the burner of the hot water heater 20 is switched from the combustion state to the non-combustion state during the hot water. Until the heat exchanger temperature Tc falls below the hot water supply set temperature Te + 5 ° C., the bypass valve 24a continues the hot water temperature control, and the mixing control valve 21 mixes as the heat exchanger temperature Tc decreases. The hot water temperature Tm is gradually raised to the hot water supply set temperature Te, and when the predetermined time (5 seconds) has elapsed from the time when the mixed hot water temperature Tm rises to the hot water supply set temperature Te-1 ° C., the bypass valve 24a is turned on by the burner. Since the temperature of the discharged hot water is prevented from being lowered by maintaining a predetermined opening corresponding to the valve opening when the temperature control of the hot water is being performed during combustion. In the middle, while suppressing the control and variation of the hot water temperature due to the switching the combustion state of the burner mixing control valve 21 to a minimum, it is possible to suppress variation in tapping flow. Therefore, even when the burner is switched from the combustion state to the non-combustion state during use of the shower, the hot water temperature and the hot water flow rate do not fluctuate in the middle, and a good feeling of use can be obtained.
[0035]
Further, in the state where the burner is combusting, even if a certain amount of hot water flow rate Qt is secured, if for some reason the can body flow rate Qc is extremely low, the hot water passing through the heat exchanger 22 Therefore, in order to prevent such a boiling state from occurring, in the hot water heater 20, the hot water flow rate Qt from the hot water heater 20 or the can in the state where the burner of the hot water heater 20 is burning. When any one of the body flow rates Qc falls below the combustion stop hot water flow rate (2.0 l / min) Qtf or the combustion stop can flow rate (1.3 l / min) Qcf, the burner stops the combustion. In the state where the burner of the water heater 20 is not combusting, both the can flow rate Qc and the tapping flow rate Qt are equal to or higher than the combustion start can flow rate (2.0 l / min) Qcn and the combustion start, respectively. If become tapping flow (3.0l / min) Qtn above, the burner is prevented from starting the combustion.
[0036]
In FIG. 3, the relationship between the tapping flow rate Qt and the bypass ratio P when the can body flow rate Qc is the combustion stop can body flow rate Qcf and the combustion start can body flow rate Qcn is shown by a one-dot chain line and a two-dot chain line, respectively. Therefore, in the figure, the hatched region is the burner combustion stop region, and the cross hatched region is the burner combustion start region, and the burner combustion is stopped when entering the combustion stop region from outside the combustion stop region. When the burner enters the combustion start region from outside the combustion start region, combustion of the burner is started. Moreover, in this hot water supply system 1, since the can flow rate Qc is only measured by the flow sensor 29, the measured hot water flow rate Qt, the heat exchanger temperature Tc, the mixed hot water temperature Tm, and the low temperature are measured. It is calculated from the water temperature Tw according to the arithmetic expression shown in Equation 1.
[0037]
[Expression 1]

[0038]
By the way, in the hot water supply system 1, as described above, during the hot water, the bypass ratio P is approximately 1.2, regardless of whether the burner is in a combustion state or a non-combustion state. Since the opening degree of the valve 24a is maintained, as shown in FIG. 4 (a), when the tapping flow rate Qt gradually decreases during tapping, the tapping flow rate Qt becomes the combustion stopped tapping flow rate Qtf. Before the temperature falls below, the can body flow rate Qc falls below the combustion stop can body flow rate Qcf, and the burner combustion stops even though the tapping flow rate Qt exceeds the combustion stop tapping flow rate Qtf. . Further, when the hot water flow rate Qt gradually increases after the start of the hot water, the hot water flow rate Qt is combusted before the can body flow rate Qc exceeds the combustion start can body flow rate Qcn, as shown in FIG. A problem arises in that combustion of the burner is not started even though the start hot water flow rate Qtn exceeds the start hot water flow rate Qt and the combustion start hot water flow rate Qtn exceeds the start hot water flow rate Qtn.
[0039]
Therefore, in this hot water supply system 1, when the can body flow rate Qc approaches the vicinity of the combustion stop can body flow rate Qcf in a state where the burner is combusting, the can body flow rate before the tapping hot water flow rate Qt falls below the combustion stop hot water flow rate Qtf. The maximum opening degree (maximum bypass ratio Pmax) of the bypass valve 24a is limited according to the tapping flow rate Qt so that Qc does not fall below the combustion stop can flow rate Qcf, and the burner is not combusting. When the hot water flow rate Qt approaches the combustion start hot water flow rate Qtn, before the can body flow rate Qc becomes equal to or higher than the combustion start water flow rate Qcn, the hot water flow rate Qt does not exceed the combustion start hot water flow rate Qtn. Accordingly, the maximum opening degree (maximum bypass ratio Pmax) of the bypass valve 24a is limited.
[0040]
That is, when the hot water flow rate Qt decreases while the burner is burning, the maximum bypass ratio Pmax at the hot water flow rate Qt at that time is calculated according to the arithmetic expression shown in Equation 2, and the calculated maximum The maximum opening degree of the bypass valve 24a is limited so as not to exceed the bypass ratio Pmax, and when the hot water flow rate Qt is increased in a state where the burner is not combusting, the calculation shown in Equation 3 is performed. According to the equation, the maximum bypass ratio Pmax at the tapping flow rate Qt at that time is calculated, and the maximum opening degree of the bypass valve 24a is limited so as not to exceed the calculated maximum bypass ratio Pmax. In FIG. 5, the maximum bypass ratio Pmax with respect to the hot water flow rate Qt calculated according to the arithmetic expressions shown in

Equations

2 and 3 is shown by a solid line and a broken line, respectively.
[0041]
[Expression 2]

[0042]
[Equation 3]

[0043]
Therefore, in this hot water supply system 1, in the state where the hot water is discharged while the burner is burning, the hot water flow rate Qt is decreased in the region indicated by the oblique lines in FIG. Is lower than the combustion stop hot water flow rate Qtf, the can body flow rate Qc becomes lower than the combustion stop can body flow rate Qcf, and combustion of the burner is surely stopped when the hot water flow rate Qt falls below the combustion stop hot water flow rate Qtf. Will be.
[0044]
Further, in the state where the burner is not combusting, the tapping flow rate Qt increases in the hatched region in FIG. 5B, so that the can body flow rate Qc exceeds the combustion start can body flow rate Qcn. After that, the hot water flow rate Qt exceeds the combustion start hot water flow rate Qtn, and combustion of the burner is surely started when the hot water flow rate Qt exceeds the combustion start hot water flow rate Qtn.
[0045]
As described above, in this hot water supply system 1, when the hot water flow rate Qt enters the small flow rate region, the maximum bypass ratio Pmax is limited, so that the bypass valve 24a can reliably control the hot water temperature. However, the temperature of the hot water is temporarily disturbed, but since there is almost no hot water discharged in such a small flow rate region, there is no particular problem.
[0046]
In the above-described embodiment, when the mixing control valve 21 switches from fixed temperature control to hot water set temperature control during hot water discharge, the temperature of the hot water (mixed hot water temperature Tm) sent from the mixing control valve 21 is the hot water supply set temperature. When a predetermined time (for example, 5 seconds) elapses from the time when the temperature rises to Te-1 ° C., the bypass valve 24a is a predetermined value corresponding to the valve opening degree when the hot water temperature control is performed during the combustion of the burner. However, the present invention is not limited to this. When the mixed hot water temperature Tm rises to the hot water supply set temperature Te-1 ° C., the bypass valve 24a is held at a predetermined opening. When the mixed hot water temperature Tm is stabilized within a predetermined temperature range centered on the hot water supply set temperature Te (for example, the hot water supply set temperature Te ± 1 ° C.), the bypass valve 24a can be held at a predetermined opening. is there.
[0047]
In the above-described embodiment, when the mixing control valve 21 is switched from the fixed temperature control to the hot water supply set temperature control during the hot water supply, the bypass valve 24a is opened when the hot water temperature control is performed during the combustion of the burner. The predetermined opening degree is equivalent to the degree (in the above-described embodiment, the opening degree of the valve is such that the bypass ratio P is about 1.2). Instead of this, it is also possible to store the valve opening just before stopping the combustion of the burner and hold it at that valve opening.
[0048]
Moreover, in embodiment mentioned above, although the fixed temperature Tf which is target temperature in case the mixing control valve 21 performs fixed temperature control is set to hot water supply preset temperature Te-10 degreeC, it is not limited to this. For example, when the hot water supply set temperature Te is 60 ° C. or more, less than 60 ° C., 35 ° C. or more, and less than 35 ° C., the case of 60 ° C. or more is 45 ° C., the case of less than 60 ° C. is 35 ° C. or more, 30 ° C. When the temperature is less than 0 ° C., the fixed temperature Tf can be set stepwise in accordance with the hot water supply set temperature Te, such as 25 ° C. In this case, however, the bypass ratio P to be maintained when combustion of the burner is stopped is calculated according to the set fixed temperature Tf, and the valve opening degree of the bypass valve 24a is set so as to be the bypass ratio P. It is necessary to maintain the opening.
[0049]
In the above-described embodiment, the hot water supply system using the water heater 20 in which the mixing control valve 21 is incorporated has been described. However, the present invention is not limited to this, and via the hot water connection unit having the mixing control valve, Needless to say, the present invention can also be applied to a hot water supply system in which a solar water heater and a normal water heater are connected.
[0050]
In the above-described embodiment, the hot water supply system in which the auxiliary heat source is solar heat has been described. However, the auxiliary heat source is not limited to such solar heat, and for example, exhaust heat of a gas engine or a gas turbine in a cogeneration system. Needless to say, the present invention can be applied to a hot water supply system using various auxiliary heat sources, such as a hot water supply system using an auxiliary heat source.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of a hot water supply system according to the present invention.
FIG. 2 is a diagram showing an operating state at the time when the mixing control valve is switched from fixed temperature control to hot water supply set temperature control during hot water discharge in the hot water supply system same as above.
FIG. 3 is an explanatory diagram for explaining a combustion stop timing and a combustion start timing of a burner in a water heater used in the above hot water supply system.
4 (a) and 4 (b) show problems when the opening degree of the bypass valve held when the burner is stopped is set to a predetermined opening degree corresponding to the opening degree of the bypass valve during combustion of the burner. It is explanatory drawing for demonstrating.
FIG. 5 is an explanatory diagram for explaining a technique for solving the same problem as above.
6A is an explanatory diagram for explaining the combustion stop timing of the burner when the above method is employed, and FIG. 6B is a diagram for explaining the combustion start timing of the burner when the above method is employed. It is explanatory drawing of.
[Explanation of symbols]
1 Hot water supply system
10 Solar water heater
14 Thermal storage tank
15, 17 Water supply pipe
16 Preheated hot water supply pipe
20 Water heater
20a controller
21 Mixing control valve
22 Heat exchanger
23 Main channel
24 Bypass channel
24a Bypass valve
25 Bypass pipe
25a solenoid valve
26a Preheating hot water temperature sensor
26b Low temperature water temperature sensor
27 Mixed hot water temperature sensor
28 Heat exchanger temperature sensor
29 Flow sensor
30 Operation remote control
30a controller

Claims

It is equipped with a mixing control valve that feeds the preheated hot water generated by the auxiliary heat source to the heat exchanger of the water heater while mixing low temperature water as necessary.
The water heater includes a main flow path for sending hot water sent from the mixing control valve through the heat exchanger, a bypass flow path connected before and after the heat exchanger in the main flow path, and the bypass A bypass valve installed in the flow path,
When the preheated hot water sent to the mixing control valve is equal to or higher than the hot water supply set temperature, the hot water supply set temperature control is performed so that the mixing control valve generates hot water at the hot water supply set temperature without heating the heat exchanger.
When the preheated hot water sent to the mixing control valve is lower than a hot water supply set temperature, the mixing control valve performs a fixed temperature control for generating hot water having a predetermined fixed temperature lower than the hot water supply set temperature, By heating the heat exchanger, hot water at the hot water supply set temperature is generated,
During heating, while the heat exchanger is being heated, the bypass valve controls the temperature of the hot water to adjust the valve opening so that the temperature of the hot water sent from the main flow path becomes the hot water supply set temperature. A hot water supply system designed to perform,
During hot water, when the mixing control valve is performing hot water supply set temperature control, the bypass valve is set to an opening just before stopping the heating of the heat exchanger or an opening during heating of the heat exchanger. A hot water supply system corresponding to a predetermined opening degree set in advance is provided.

It is equipped with a mixing control valve that feeds the preheated hot water generated by the auxiliary heat source to the heat exchanger of the water heater while mixing low temperature water as necessary.
The water heater includes a main flow path for sending hot water sent from the mixing control valve through the heat exchanger, a bypass flow path connected before and after the heat exchanger in the main flow path, and the bypass A bypass valve installed in the flow path,
When the preheated hot water sent to the mixing control valve is equal to or higher than the hot water supply set temperature, the hot water supply set temperature control is performed so that the mixing control valve generates hot water at the hot water supply set temperature without heating the heat exchanger.
When the preheated hot water sent to the mixing control valve is lower than a hot water supply set temperature, the mixing control valve performs a fixed temperature control for generating hot water having a predetermined fixed temperature lower than the hot water supply set temperature, By heating the heat exchanger, hot water at the hot water supply set temperature is generated,
During heating, while the heat exchanger is being heated, the bypass valve controls the temperature of the hot water to adjust the valve opening so that the temperature of the hot water sent from the main flow path becomes the hot water supply set temperature. A hot water supply system designed to perform,
In the hot water, the bypass valve stops the heating of the heat exchanger, and then waits until the temperature of the heat exchanger falls below a predetermined temperature. Hot water temperature control is performed to adjust the valve opening so that the temperature becomes the hot water supply set temperature, and when the temperature of the heat exchanger falls below a predetermined temperature, the temperature is maintained at a predetermined fixed opening. It is supposed to
In the hot water, after the mixing control valve shifts from fixed temperature control to hot water supply set temperature control, when the hot water near the hot water supply set temperature starts to be sent from the mixing control valve, the bypass valve is connected to the heat exchanger. The hot water supply system is characterized in that it is held at a predetermined opening degree that corresponds to the opening degree immediately before stopping the heating or the opening degree during heating of the heat exchanger.

During the hot water, after the mixing control valve shifts from the fixed temperature control to the hot water supply set temperature control, the hot water delivered from the mixing control valve is a predetermined lower than the hot water supply set temperature set in advance with respect to the hot water supply set temperature When the temperature is raised to a temperature, the bypass valve is maintained at a predetermined opening degree that corresponds to the opening degree immediately before stopping the heating of the heat exchanger or the opening degree during heating of the heat exchanger. The hot water supply system according to claim 2, wherein the hot water supply system is configured as described above.

During the hot water, after the mixing control valve shifts from the fixed temperature control to the hot water supply set temperature control, the hot water delivered from the mixing control valve is a predetermined lower than the hot water supply set temperature set in advance with respect to the hot water supply set temperature When the predetermined time has elapsed from the time when the temperature is raised to the temperature, the bypass valve is set in advance, which corresponds to the opening just before stopping the heating of the heat exchanger or the opening during heating of the heat exchanger. The hot water supply system according to claim 3, wherein the hot water is maintained at a predetermined opening degree.

In a state where the burner that heats the heat exchanger is burning, when the flow rate of hot water passing through the heat exchanger falls below a predetermined combustion stop warm water flow rate, or the flow rate of hot water from the water heater is The burner stops the combustion when it falls below the predetermined stoppage of hot water flow,
In the state where the burner is burning, when the flow rate of hot water passing through the heat exchanger approaches the vicinity of the combustion stop hot water flow rate, the flow rate of hot water passing through the heat exchanger before the hot water flow rate falls below the combustion stop hot water flow rate 5. The hot water supply system according to claim 1, wherein the opening degree of the bypass valve is adjusted so that the flow rate does not fall below the combustion stop hot water flow rate.

In a state where the burner for heating the heat exchanger is not combusted, the flow rate of hot water passing through the heat exchanger is equal to or higher than a predetermined combustion start hot water flow rate, and the flow rate of hot water from the water heater is predetermined. When the combustion start hot water flow rate is exceeded, the burner starts to burn,
In a state where the burner is not combusted, when the hot water flow rate approaches the vicinity of the combustion start hot water flow rate, the hot water flow rate that exceeds the combustion start hot water flow rate becomes greater than or equal to the combustion start hot water flow rate before the hot water flow rate that passes through the heat exchanger exceeds the combustion start hot water flow rate. The hot water supply system according to claim 1, 2, 3, 4 or 5, wherein the opening degree of the bypass valve is adjusted so as not to become.