DE102005044372A1 - Device for rinsing off reaction products, dead microorganisms and bio-film fragments, comprises water circulation pipe system with circulating pump, reflux preventer, water heater, drinking water heating system and switch valve - Google Patents

Abstract

The device (1) for rinsing off reaction products, dead microorganisms and bio-film fragments, comprises a water circulation pipe system with a circulating pump, a reflux preventer, a water heater, a drinking water heating system, and a switch valve. The reflux preventer is used for reheating a circulatory water flow to a preset temperature before the flow through water heater that is connected to the drinking water heating system (6). The valve is installed in direction of flow in front of the preventer and behind the pump so that the water flow avoids the system (6) by bypass line. The device (1) for rinsing off reaction products, dead microorganisms and bio-film fragments, comprises a water circulation pipe system with a circulating pump, a reflux preventer, a water heater, a drinking water heating system and a switch valve. The reflux preventer is used for reheating a circulatory water flow to a preset temperature before the flow through water heater that is connected to the drinking water heating system (6). The valve is installed in direction of flow in front of the preventer and behind the pump so that the water flow avoids the system (6) by bypass line. The circulatory water flow enters into the reaction area of a hot water tank, after a defined time over a hot water pipe systems intended to transport drinking water and again flows over the water circulation pipe system of the circulating pump within the device. The reflux preventer is installed and enters into a drinking warm water line system with the help of instrumentation and measurement control (4), during a less operation time interval, e.g. at night, a transfer valve drives from operating position into the treatment position. A water metering counter with a pulse generator, measuring probes and a metering unit (3) with the metering valve that are installed in front of and behind the circulating pump are activated so that the water metering counter with pulse generator (7) controls the dosing pump in quantitative proportion to the flow rate of the circulating pump. Activating a water metering counter with a pulse generator, measuring probes and a metering unit with the metering valve are installed in front of and behind the circulating pump so that the water metering counter with pulse generator controls the dosing pump in quantitative proportion to the flow rate of the circulating pump. A metering pump adds a dosing agent such as chlorine dioxide into the drinking warm water line system over the metering valve until the circulating pump is switched off using the instrumentation and measurement control. During stagnating circulation flow rate, the dosing agent completely unfolds its germicidal effect, and reacts with the organic materials in warm drinking water and circulation line systems to form breath- and cell-poison chlorite. A rinsing-off valve is opened for a defined time interval, so that the untreated warm drinking water flowing over the drinking water heating plant into warm drinking water- and circulation line-system and rinses off the reaction products, dead microorganisms and bio-film fragments into a sewage system. The functions of the instrumentation and measurement control are implemented manually or semi-automatically. The metering unit with metering pump and metering valve, the instrumentation and measurement control with the measuring probes, the switching valve with the reflux preventer, the water metering counter with the pulse generator, the circulating pump and the rinsing-off valve are completely piped and electrically wired in a framework rack and/or on a mounting plate as an operation-ready stationary or as an operation-ready mobile device in warm drinking water- and circulation line-systems, or are connected and operated for the purpose of prophylaxis, and are intended in a drinking water heating system. The drinking water heating system is included into a chemical treatment and rinsing-off procedure through the omission of the switching valve and the bypass line with the reflux preventer or by the presence of the switching valve and the bypass line with reflux preventer in the device and retention of the operating position of the switching valve during the chemical treatment and the rinsing-off procedure.

Description

contraption to rinse of reaction products, dead microorganisms and biofilm fragments, after chemical treatment and during operating periods, from domestic hot water systems that provide water to the public submit.

Known Devices for the chemical treatment of domestic hot water systems against human pathogenic microorganisms and biofilms, dose as prophylaxis constantly, 24 h / day, in the dispensing volume flow volume-proportional dosing agent, eg. As chlorine dioxide.

The DVGW worksheet W224 from April 1986 is under the heading "Chlorine dioxide in water treatment ". It describes and schematically illustrates the operation, the control as well as the measurement and documentation of the chlorine dioxide dosage, under consideration the reactions of chlorine dioxide as well as the hygienic aspects.

The Company iotronic describes on the Internet under www.iotronic.de chlorine dioxide dosing systems after the listed Prior art with particular measurement of chlorine dioxide concentration, as well as the company Grünbeck, Water treatment, in a 4-page brochure No. 05.03.05 a "permanent disinfection for continuous germ killing from drinking, operating and waste water ", via a chlorine dioxide dosing system the illustrated prior art.

The issued by the Federal Environmental Agency "List of processing substances and disinfection procedure "according to § 11 Trinkw.V.2001 As of Sept. 2002, Part C "Processes, used for disinfection "expressly refers to reaction products to be observed as chlorite and chlorate at a chlorine dioxide dosage out.

Duration dosages for the continuous germ killing be operated prophylactically cause dead according to regulations Microorganisms and biofilm fragments but also inevitably and inevitable reaction products from the dosing z. As chlorine dioxide, by the users of the water over the tap fittings with the TWW taken and possibly be recorded.

Of the DVGW publication - DVGW project W 4/03/03 - "Chlorite formation when disinfecting with chlorine dioxide ", resulting in up to 80% of the dosed Chlorine dioxide amount converted to chlorite, as respiratory and cellular toxin applies.

In the journal 1KZ-Haustechnik Heft 18/2004 on the subject "Legionella - human pathogenic water-permeable bacteria"
Part 6: Process Engineering Systems for Water Treatment, page 40, were developed by Prof. Dr. Ing. Dieter Kreysig and others the problems of chlorite formation in the chlorine dioxide dosage in drinking water heating and Trinwasserleitungsanlagen described.

On the one hand can be an online measurement of the chlorite content or a determination from the metered amount of chlorine dioxide not sure to prevent it Enrichments of chlorite over the limit in drinking water heating and domestic hot water systems comes and thus to the danger the user of the water.

on the other hand can be a big one Proportion of chlorine dioxide its full disinfecting effect due to missing Reaction time can not be achieved if, as usual in the prior art, proportional to the amount is metered to Zapfwassermenge, and depending on the arrangement of the metering over in a few minutes the hot water taps restore the domestic hot water system leaves.

• – daß die chemische Behandlung des Trinkwarmwasser- und Zirkulationsleitungssystems während eines betriebsarmen Zeitraumes, z. B. nachts erfolgt
• – durch ein Umschaltventil, die chemisch zu behandelnden Leitungssysteme zirkulationstechnisch von dem Trinkwassererwärmungssystem getrennt werden ohne Einschränkung der Warmwasserzapfmöglichkeit
• – sowie über ein Zeitprogramm ein im Zirkulafionsleitungssystem plazierter Dosierwasserzähler und die Chlordioxid-Dosierpumpe aktiviert werden, und
• – die chemische Behandlung der Trinkwarmwasser- und Zirkulationsleitungssysteme beginnt,
• – nach Erreichen des Grenzwertes für Chlordioxid, oder nach einem vorgegebenen Zeitraum, die Meß- und Regeltechnik die Zirkulationspumpe für eine definierte Zeitspanne abschaltet, so daß das Dosiermittel seine volle keimtötende Wirkung entfaltet, aber auch mit den organischen Stoffen im Rohrleitungsnetz reagiert,
• – die Reaktionsprodukte, u. a. das Chlorit, abgestorbene Mikroorganismen sowie Biofilmfragmente, durch Öffnen eines im Zirkulationsleitungssystems plazierten Ausspülventils durch nachströmendes, chemisch unbehandeltes, Trinkwarmwasser aus den Leitungssystemen ausgespült werden,
• – das gesamte Trinkwassererwärmungssystem und die Trinkwarmwasserleitungssysteme durch die Meß- und Regeltechnik in ihren bestimmungsgemäßen Betrieb zurückversetzt werden,
• – und sich, wie in 1 dargestellt, durch diese erfindungsgemäßen anlagen-, verfahrens- und betriebstechnischen Maßnahmen durch effektivere Nutzung des Dosiermittels ein wirtschaftlicherer Betrieb ergibt und für die Nutzer des Trinkwarmwassers, z. B. in einem Krankenhaus, eine Gesundheitsgefährdung durch Aufnahme der Reaktionsprodukte weitgehend ausgeschlossen ist.

Here now, the invention begins and wants to achieve that all the disadvantages that are caused by a usually proportional to the quantity of tap water addition of a dosing agent, eg. As chlorine dioxide result, are excluded,

• - That the chemical treatment of the domestic hot water and circulation piping system during a low-service period, eg. B. at night
• - By a switching valve to be chemically treated piping systems circulation technology separated from the drinking water heating system without limiting the hot water tap option
• - And via a time program placed in Zirculafionsleitungssystem dosing water meter and the chlorine dioxide metering pump are activated, and
• - the chemical treatment of domestic hot water and circulation piping systems begins,
• - After reaching the limit value for chlorine dioxide, or after a predetermined period of time, the measurement and control technology switches off the circulation pump for a defined period of time, so that the dosing unfolds its full germicidal effect, but also reacts with the organic substances in the pipeline network,
• The reaction products, including the chlorite, dead microorganisms and biofilm fragments, are flushed out of the piping systems by opening a flushing valve placed in the circulation piping system by means of inflowing, chemically untreated, domestic hot water;
• - the entire drinking water heating system and the domestic hot water systems are returned to their intended operation by the measuring and control technology,
• - and, as in 1 represented by these inventive plant, procedural and operational measures through more effective use of the dosing a more economical operation and for the users of the domestic hot water, z. As in a hospital, a health hazard by including the reaction products is largely excluded.

4. invention

aim The invention is to provide devices and in low-demand periods to operate, to rinse of reaction products, dead microorganisms and biofilm fragments chemical treatment from domestic hot water systems the water to the public, to prevent these Reaction products, microorganisms and fragments from hot water taps be taken with the water and endanger the users of this water health.

The object is achieved by the described in claim 1 and in 1 shown solved device with the features shown there.

By a changeover valve in the circulation piping system becomes the one of the circulation pump recycled circulation flow hydraulically separated from the drinking water heating system and via a bypass line behind the drinking water heating system integrated into the drinking water supply system.

In the circulation piping system is u. a. a dosing water meter with Pulse generator installed, the metering pump of the metering device proportionally drives, so that this, the performance of the circulation pump Accordingly, a certain amount of dosing via the metering valve in the Circulation volume flow dosed and this dosing from there on the bypass line into the domestic hot water system and the circulation piping system arrives.

Via measuring probes as well as the measuring and control technology become the permissible Limits of the dosing agent monitored, regulated and registered.

To Reaching the limits and / or after a programmed period of time is the circulation pump for switched off a certain duration, so that the dosing his full germicidal Unfolded, but also with the organic substances in the drinking water and circulation piping system responds, u. a. to the respiratory and Cell toxin chlorite.

Then the opens Measuring and Control technology a flush valve in the circulation piping system over which the dead microorganisms, Biofilm fragments and the reaction products from the whole drinking water supply system and Circulation piping system by inflowing, chemically untreated Hot water rinsed out become.

To a programmed rinsing time, offset the measuring and control technology, the entire drinking water heating system and the domestic hot water and circulation piping systems back to their intended operation.

The Supplying the taps with drinking water is during the chemical treatment and rinsing time not interrupted.

By the discontinuous chemical treatment of the domestic hot water system and the circulation piping system there is a risk of dosing agent resistance the microorganisms significantly reduced.

Further advantageous arrangement and design features of the invention are from the claims removable. Some embodiments of the Invention will be described below with reference to the drawings.

It demonstrate:

1 a device for rinsing reaction products, dead microorganisms and biofilm fragments, after chemical treatment and during periods of low power, from domestic hot water systems that deliver water to the public, being given by the particular design of the drinking water heating system of this only drinking water at 60 ° C in the domestic hot water system , which has been subjected to a thermal treatment, so that the chemical treatment is the biofilm degradation and killing of the free-living microorganisms in the domestic hot water system and circulation piping system, but it is inevitable that reaction products of z. As chlorine dioxide, including the respiratory and cellular toxin chlorite.

2 a device accordingly 1 however, as a prefabricated stationary version on egg ner mounting plate or in a frame or as a mobile version for use as needed in various objects.

3 and 4 the state of the art of a device for the prophylactic chemical treatment of a likewise built according to the prior art drinking water heating system - from which in the sense of Trinkw.V.2001 water is delivered to the public - and the downstream drinking water and circulation piping systems, against human pathogenic microorganisms and biofilms By metering, 24 h per day, of, for example, chlorine dioxide in the cold water supply volume proportional to the tap volume flow to treat the water in the drinking water heating system necessarily also chemically.

The Reaction products, u. a. the chlorite, dead microorganisms and biofilm fragments remain in the drinking water heating system and in the domestic hot water and circulation piping system the living microorganisms as food or accumulate on, are taken with the hot water on the taps and in certain circumstances taken by the users.

5 the state of the art like 3 and 4 however, only the domestic hot water and circulating piping systems are treated against human pathogenic microorganisms and biofilms. In the drinking water heating system, however, it may come to construction enrichment, due to construction and operational reasons, which by tapping into the piping systems ( 10 ) and ( 11 ) is towed up to the taps ( 2 ). The disadvantages, how to 3 and 4 described, also exist for the arrangement 5

6 and 7 Embodiments with devices according to the invention, the drinking water heating systems ( 6 ) are connected downstream with integrated thermal disinfection from which components, eg. B. circulation pumps ( 9 ) and the changeover valve ( 5 ), were included in the device according to the invention, so that all features and functions are provided for the intended operation and the domestic hot water and circulation piping systems ( 10 ) and ( 11 ) can be operated within the meaning of the invention.

In more detail Described with reference number

According to 1 flows during Zapfruhezeiten the circulation volume flow, pushed by the circulation pump ( 9 ), about the components ( 7 ) ( 12 ) ( 13 ) ( 5 ) ( 17 ) of the device ( 1 ) in the Durchflußwassererwärmer ( 50 ) of the drinking water heating system ( 6 ), is heated to a target temperature of 60 ° C, enters the reaction space ( 60.1 ) of the hot water storage tank ( 60 ), leaves this after a defined period thermally disinfected in the domestic hot water system ( 10 ) and flows through the circulation piping system ( 11 ) as well as the measuring probe ( 14 ) of the circulation pump ( 9 ) again.

Is the device ( 1 ) according to 1 through the measuring and control technology ( 4 ) is activated at a certain time, the program for the chemical treatment of the domestic hot water system ( 10 ) and the circulation piping system ( 11 ) with subsequent rinsing of the reaction products, the dead microorganisms and the biofilm fragments according to the following steps:

step 1 : Switchover of the changeover valve ( 5 ) in the treatment position "AB" → "B", so that the circulation volume flow through the backflow preventer ( 18 ) and the bypass line ( 15 ) and the domestic hot water system ( 10 ), the circulation piping system ( 11 ), the measuring probe ( 14 ) and the flushing valve ( 16 ) of the circulation pump ( 9 ) flows back through without the drinking water heating system ( 6 ) to be reheated.

step 2 : By activating the dosing device ( 3 ) is controlled in proportion to the volume flow rate of the dosing water meter with pulse generator ( 7 ), via the dosing pump ( 8th ) a certain amount of dosing agent, for. As chlorine dioxide, added.

The water content of the domestic hot water system ( 10 ) and the circulation piping system ( 11 ) is circulated about 2 times per hour, so that after about 30 minutes, the entire water content is evenly mixed with dosing. The dosing agent concentration is monitored, controlled and registered by the measuring and control technology ( 4 ) and via the measuring probes ( 13 ) and ( 14 ).

step 3 : After z. B. 1 time circulation of the water content or depending on set limits, is determined by the measurement and control technology ( 4 ) the circulation pump ( 9 ) for a defined period of time, so that the dosing agent unfolds its full germicidal activity and acts on the biofilm, but also with the organic substances in the domestic hot water system ( 10 ) and circulation piping system ( 11 ) reacts to the respiratory and cytotoxic chlorite.

step 4 : The measuring and control technology ( 4 ) opens the flush valve ( 16 ), on the dead microorganisms, biofilm fragments and the reaction products, eg. As chlorite, from the entire drinking water system ( 10 ) and circulation piping system ( 11 ) over a defined period of time, depending on the volume of the treated pipe tems are flushed out into the wastewater by inflowing, chemically untreated domestic hot water, monitored by the measuring and control technology ( 4 ).

step 5 : The measuring and control technology ( 4 ) repeats the steps 2 to 4 or displaces the entire drinking water heating system ( 6 ) and the domestic hot water ( 10 ) and circulation piping systems ( 11 ) back to the intended operation.

The supply of the taps ( 2 ) with domestic hot water is not interrupted during the chemical treatment and rinsing process.

The 2 shows the device ( 1 ) for rinsing reaction products, dead microorganisms and biofilm fragments, after chemical treatment and during periods of inactivity, from domestic hot water systems delivering water to the public, as a stationary or mobile device used for prophylaxis in newly erected or rehabilitated existing contaminated domestic hot water ( 10 ) and circulation piping systems ( 11 ), as in 1 shown, is used, with all features of the invention.

In 3 the state of the art of a device is shown for the prophylactic, chemical treatment of a drinking water heating system ( 6 ) - designed as a storage loading system - from which in the sense of Trinkw.V.2001 water is delivered to the public, as well as the downstream drinking water supply system ( 10 ) and circulation piping system ( 11 ) against human pathogenic microorganisms and biofilms by adding - 24 h / d - z. B. Chlorine dioxide via the metering pump ( 8th ), and the metering valve ( 12 ) into the cold water supply to the drinking water heating system ( 6 ).

The activation of the dosing pump ( 8th ) via the dosing water meter with pulse generator ( 7 ) proportionally to the bleed volume flow, the monitoring of the dosing agent concentration via the measuring probes ( 13 ) and ( 14 ). The circulation pump ( 9 ) is constantly operated or max. 8 h / 24 h switched off.

The reaction products, including the respiratory and cell toxin chlorite, dead microorganisms and biofilm fragments are mixed with the domestic hot water via the hot water taps ( 2 ), possibly taken up by the users or remain in the drinking water heating system ( 6 ) and in the domestic hot water and circulation piping system ( 10 ) and ( 11 ), serve the still living microorganisms as food and accumulate.

The 4 shows the state of the art of a device for the prophylactic, chemical treatment of a drinking water heating system ( 6 ) - Version as a horizontal storage water heater - from which water is released to the public in the sense of the Trinkw.V.2001, as well as the downstream domestic hot water and circulation piping system ( 10 ) and ( 11 ), with the operation and features such as 3 described.

In 5 Also shown is the state of the art, a device for the prophylactic, chemical treatment of only the domestic hot water system ( 10 ) and the circulation piping system ( 11 ) against human pathogenic microorganisms and biofilms by adding - 24 h / d - z. B. Chlorine dioxide via the metering pump ( 8th ) and the metering valve ( 12 ) directly into the domestic hot water system ( 10 ) from where dosing agent through the bleed flow and through the circulation pump ( 9 ) also into the circulation pipeline network ( 11 ) is distributed into it.

In the drinking water heating system ( 6 ), however, it may come to construction enrichment, due to design and operational engineering, which by tapping into the piping systems ( 10 ) and ( 11 ) is towed up to the taps ( 2 ).

The activation of the dosing pump ( 8th ) via the dosing water meter with pulse generator ( 7 ), proportional to the volume flow of the meter, the monitoring of the metering agent concentration via the measuring probes ( 13 ) and ( 14 ).

The circulation pump ( 9 ) is constantly operated or max. 8 h / 24 h switched off.

The reaction products, including the respiratory and cell toxin chlorite, dead microorganisms and biofilm fragments are mixed with the domestic hot water via the hot water taps ( 2 ) may be taken by users or remain in the drinking water heating system and in the domestic hot water and circulation 10 ) and ( 11 ), serve the still living microorganisms as food and accumulate.

6 and 7 provide drinking water heating systems ( 6 ) with integrated thermal disinfection, which during normal operation constantly drinking hot water in the downstream domestic hot water system ( 10 ) with the microbiological quality according to §5 of Trinkw.V.2001, with downstream devices according to the invention ( 1 ), in the existing components, eg. B. the circulation pump ( 9 ) and the changeover valve ( 5 ), drinking water heating systems ( 6 ) are included so that the device according to the invention ( 1 ) can be operated as intended, as to 1 and 2 be wrote.

Claims (4)

Contraption ( 1 for rinsing reaction products, dead microorganisms and biofilm fragments, after chemical treatment and during periods of low activity, from domestic hot water systems which release water to the public, comprising a circulation piping system (US Pat. 11 ) with a circulation pump ( 9 ) and a backflow preventer ( 17 ), which is used to reheat the circulation volume flow to the setpoint temperature in front of the flow water heater ( 50 ) of the drinking water heating system ( 6 ), this circulation volume flow into the reaction space ( 60.1 ) of the hot water storage tank ( 60 ), after a defined period of time via the domestic hot water system ( 10 ) and via the circulation piping system ( 11 ) of the circulation pump ( 9 ) within the device ( 1 ), characterized in that 1.1 in the flow direction before the backflow preventer ( 17 ) and behind the circulation pump ( 9 ) a switching valve ( 5 ) is installed so that 1.2 the circulation volume flow through the bypass line ( 15 ) into which a backflow preventer ( 18 ), the drinking water heating system ( 6 ) and 1.3 behind ( 6 ) into the domestic hot water system ( 10 ), if 1.4 via a time program, belonging to the measuring and control technology ( 4 ), while 1.5 a low-operating time, z. B. at night, 1.6 the switching valve ( 5 ) from the operating position "AB" → "A" to the treatment position "AB" → "B" and the dose counter with pulse generator ( 7 ) the measuring probes ( 13 ) and ( 14 ) and the dosing device ( 3 ) with the dosing valve ( 12 ), in front of and behind the circulation pump ( 9 ), so that, 1.7 proportional to the volume flow of the circulation pump ( 9 ) the dosing water meter with pulse generator ( 7 ) the dosing pump ( 8th ) and this 1.8 via the metering valve ( 12 ) Dosing agent, eg. As chlorine dioxide, in the domestic hot water system ( 10 ) up to 1.9 after a predetermined period of time, or after reaching the limit values, via the measuring and control technology ( 4 ) the circulation pump ( 9 ) is switched off and 1.10 stagnant circulation volume flow the dosing unfolds its full germicidal effect, but also with the organic substances in the domestic hot water and circulation piping system ( 10 ) and ( 11 ) reacts to the respiratory and cellular toxin chlorite, so that 1.11 to protect the users of the treated water after a defined period of time for a defined period of time the Ausspülventil ( 16 ) is opened, characterized in that via the drinking water heating system ( 6 ) into the domestic hot water and circulation piping system ( 10 ) and ( 11 ) inflowing, untreated domestic hot water rinsing the reaction products, dead microorganisms and biofilm fragments into the sewage system 1.12 the drinking water heating system ( 6 ) and the domestic hot water and circulation 10 ) and ( 11 ) by the measuring and control technology ( 4 ) are returned to their intended operation, or 1.13 one, several or all functions of the measuring and control technology ( 4 ) be carried out manually or semi-automatically, so that 1.14 at the hot water taps ( 2 ) untreated water, largely free of reaction products and dead microorganisms for which users are available. Apparatus according to claim 1, characterized in that 2.1 the components metering device ( 3 ) with dosing pump ( 8th ) and metering valve ( 12 ), the measuring and control technology ( 4 ) with the measuring probes ( 13 ) and ( 14 ), the changeover valve ( 5 ) with the backflow preventers ( 17 ) and ( 18 ) as well as the dosing water meter with pulse generator ( 7 ), the circulation pump ( 9 ) and the flushing valve ( 16 ) ready-cased and electrically wired in a rack and / or 2.2 on a mounting plate as a ready-to-use stationary or 2.3 ready-to-use mobile device in drinking water and circulation systems ( 10 ) and ( 11 ) as needed, or 2.4 for prophylaxis. Apparatus according to claim 1 or 2, characterized in that the 3.1 drinking water heating system ( 6 ) constantly or 3.2 as required in the chemical treatment and the flushing is included by eliminating the switching valve ( 5 ) and the bypass line ( 15 ) with the backflow preventer ( 18 ) or 3.3 by keeping the switching valve ( 5 ) and the bypass line ( 15 ) with non-return valve ( 18 ) in the device ( 1 ) and maintaining the operating position "AB" → "A" of the switching valve ( 5 ) during the chemical treatment and rinsing process. Apparatus according to claim 1, characterized in 4.1 the individual components dosing device ( 3 ) with dosing pump ( 8th ) and metering valve ( 12 ), the measuring and control technology ( 4 ) with the measuring probes ( 13 ) and ( 14 ), the changeover valve ( 5 ) with the backflow preventers ( 17 ) and ( 18 ) as well as the Dosing water meter with pulse generator ( 7 ), the circulation pump ( 9 ) and the flushing valve ( 16 ) in a drinking water heating system to be re-planned ( 6 ) or 4.2 for remediation and, during manufacture, directly into this drinking water heating system ( 6 ) installation and functional technology, under 4.3 possible use of existing components such as the z. B. circulation pump ( 9 ) and the backflow preventer ( 17 ).