DE10122475A1 - Improving circulation in drinking water heating systems involves circulating in distribution network and charging hot water storage device using common circulation pump for both processes - Google Patents

Abstract

The method involves circulating in the distribution network (9) and charging the hot water storage device (1) using a common circulation pump (4) designed for both processes whose feed flow is changed over or distributed by a 3-way valve (5) so that both heating the storage device and circulation can take place in parallel and the storage device temperature and the circulation temperature can be reached as soon as possible.

Description

According to the state of the art, drinking water heating systems are used for temperature maintenance in the hot water pipe equipped with circulation pipe and circulation pump. In principle, the DHW heater is charged, directly or indirectly, by means of integrated heat exchanger and, if necessary, a separate charging pump or by means of external heat exchanger and separate charging pump. The circulation pump is from this operated independently, mostly only time-controlled. This state of the art is also in the system with possibly uncontrolled external energy feed such as solar energy, heat Solid fuel boilers, u. a. used.

For systems with a memory in small systems, this system works except for the following Disadvantage.

Drinking water storage in small systems with integrated heat exchangers require if necessary, a separate supercharging pump in order to completely heat up the storage tank hygienic reasons (normative requirements) or for economic reasons (increase of NL number). This results in investment costs for this charging pump and operating costs for operating this pump.

The running time of the charging pump for the heating process of the storage from Cold water inlet temperature TW (usually 10 ° C) to drinking water outlet temperature TWW (usually 60 ° C) also determines the period for covering the circulation losses of the Systems from i. d. Rule 55 ° C to 60 ° C.

The circulation pump, since it is time-controlled, supports uncontrolled use of external energy impermissibly high drinking water temperatures greater than 60 ° C in the drinking water network (Risk of scalding and increased heat loss). With mechanical temperature limiters on the other hand, so-called thermal balancing valves, the circulation line is shut off and the circulation pump is idling (pump overheating). Until the  Shut off the regulating valves, parts of the drinking water network become high tempered water operated.

No full charging of the storage due to the opposing Flow direction of circulation and charging pumps. While the charge pump the Tries to charge the storage tank from top to bottom with hot water of 60 ° C if necessary Circulation pump from the circulation system in the opposite direction to be charged with the amount of circulation water from bottom to top.

Because central heating of drinking water in combination with heating both Charging process as well as the process of covering the circulation losses for the heating triggers a priority operation with increased flow temperatures in the heating system Systems with separate supercharging pumps for long operating losses when heating and increased Flow temperatures. Therefore, it was proposed to cover the period Circulation losses, for example through a second pump or through speed control of the Shorten charging pump. The selected technical effort is considerable, on the other hand, this measure enabled the system to function properly can be achieved.

Larger drinking water heating systems are often equipped with several storage tanks. For hygienic and economic reasons, several storage tanks are in series switched and heated with a common heat exchanger and a charging pump. With this circuit, there was sufficient and sufficient memory Connected load more and more problems, especially when the circulation line was connected to the cold water inlet in front of the storage tank as usual. At this Connection technology, the circulation is equipped with a non-return valve, which at Taps to prevent cold water from entering the circulation network. In large plants The type described with several recharge memories and circulation resulted in the following Defects.

For systems with multiple memories in large systems, this system works except following disadvantages.

All the disadvantages described in advance for systems with a memory in small systems were.

No full charging of the storage due to the opposing Flow direction of circulation and charging pumps. While the charge pump the Tries to charge the storage tank from top to bottom with hot water of 60 ° C if necessary Circulation pump from the circulation system in the opposite direction to be charged with the amount of circulation water from bottom to top.

In the case of systems that were implemented, one had to make a decision: a charging pump and a circulation pump only operate alternately.

In this way, the conflicting operation of the pumps could be avoided, but it did to impermissibly long downtimes with low temperatures in the circulation system. Germination of Legionella in the circulation system through downtimes, that is, through Stagnation at too low temperatures while charging the memory from 10 on 60 ° C, during the taps and during the reheating of circulation losses of 55 to 60 ° C via the cylinder primary pump.

novelty

To solve all the problems described in central drinking water heating systems with storage tanks, the invention proposes charging the storage tanks ( 1 ) and conveying the amount of circulation water in the circulation line ( 9 ) via a common pump ( 4 ) in conjunction with a three-way valve ( 5 ). that both the circulation operation is improved, and the charging operation can take place simultaneously with the circulation operation.

For this purpose, the common pump ( 4 ) is designed for the commonly required delivery rate and, in order to adapt to the different delivery rates and delivery pressures, depending on the position of the three-way valve ( 5 ), is operated in a constant or speed-controlled manner. With the help of the three-way valve ( 5 ) and the common pump ( 4 ), depending on the requirement, both a shortened reheating process for circulation losses and simultaneous charging and circulation operation with the middle position of the three-way valve ( 5 ) possible. Both the positions of the three-way valve ( 5 ) and the required speed of the pump ( 4 ) is controlled by an electronic control ( 6 ) so that the setpoints for the storage temperature, for. B. 60 ° C, and for the circulation temperature, for. B. 55 ° C, have priority and the shortest possible interruption to heating is achieved (highest possible speed while covering the circulation losses in the memory). With simultaneous circulation and charging when the flow rates are divided by the three-way valve ( 5 ), standstill for the circulation is avoided. The circuit according to the invention for charging and circulation can be used according to FIG. 3 in systems with solar energy for charging the preheater, which is required for hygienic reasons. The circuit for charging and circulation according to the invention can also be used according to FIG. 4 in systems for solar energy with drinking water mixer ( 7 ) for charging the preheater, which is required for hygienic reasons. Furthermore, systems with a series connection of the charging store and the reheating store can also be equipped with the newly invented circuit via a drinking water mixer according to FIGS. 5, 7. The circuits acc. Fig. 1, 2, 3, 4 and 6, by way of example gem. Fig. 8, can also be used with a pipe in pipe system ( 16 ), a coaxial pipe with opposite flow of the hot water pipe ( 8 ) and circulation pipe ( 9 ). The accumulators ( 1 ) are charged from top to bottom.

LIST OF REFERENCE NUMBERS

1

General storage

2

integrated heat exchanger

3

external heat exchanger

4

pump

5

Three-way valve

6

regulator

7

drinking water mixer

8th

DHW hot water pipe

9

Circulation line TWZ

10

Cold water pipe TW

11

check valve

12

Charging line for drinking water heating systems

13

Bypass line circulation TWZ

14

Bypass line cold water TW

15

Drinking water mixer preheating

16

Pipe in pipe system

Claims (10)

1. A method for improved circulation and charging of drinking water heating systems, characterized in that the circulation of the distribution network ( 9 ) and the charging of the hot water tank ( 1 ) via a common, designed for both processes circulation pump ( 4 ), the flow rate using a three-way valve ( 5 ) is switched over or divided so that both the storage heating and the circulation operation can take place in parallel or the storage temperature and the circulation temperature can be reached as quickly as possible ( Fig. 1-2). 2. The method according to claim 1, characterized in that the speed of the pump ( 4 ) and the position of the three-way valve ( 5 ) by an electronic control ( 6 ) to the fastest possible reaching the desired temperature are controlled optimally. 3. The method according to claim 1 and 2, characterized in that the charge store ( 1 ) with an external heat exchanger ( 3 ) are operated ( Fig. 1). 4. The method according to claim 1 and 2, characterized in that the memory ( 1 ) can be operated with an integrated heat exchanger ( Fig. 2). 5. The method according to claim 1 and 2, characterized in that the described function of the pump ( 4 ), three-way valve ( 5 ) and control ( 6 ) also for charging preheaters in bivalent solar storage ( 1 ) with further integrated heat exchangers ( 2 ) low Temperature levels is used. ( Fig. 3). 6. The method according to claim 5, characterized in that the described function of the pump ( 4 ), three-way valve ( 5 ) and control ( 6 ) in bivalent stores ( 1 ) higher temperature levels than in the hot water line ( 8 ), with a thermal or Motorized drinking water mixer ( 7 ) is controlled so that a constant hot water temperature in the hot water line ( 8 ) and circulation line ( 9 ) is achieved in circulation operation, as well as in tap operation and corresponding circulation connection to the storage tank ( 1 ) ( Fig. 4). 7. The method according to claim 5, characterized in that the described function of the pump ( 4 ), three-way valve ( 5 ), control ( 6 ) and drinking water mixer ( 7 ) also for the series connection of charging memories ( 1 ) with an external heat exchanger ( 3 ) and reheater ( 1 ) with integrated heat exchanger ( 2 ) is used ( Fig. 5). 8. The method according to claim 6 and 7, characterized in that the described function of the pump ( 4 ), three-way valve ( 5 ) and drinking water mixer ( 7 ) via the bypass line circulation ( 13 ), check valve ( 11 ) and drinking water mixer ( 7 ) in the circulation mode and via the bypass line cold water ( 14 ), non-return valve ( 11 ) and drinking water mixer ( 7 ) in the tap operation, protection against scalding in the hot water line ( 8 ) and circulation line ( 9 ) ( FIG. 6). 9. The method according to claim 7 and 8, characterized in that the described function of the pump ( 4 ), three-way valve ( 5 ) and drinking water mixer ( 7 ) also in the series connection of the charge accumulator ( 1 ) with an external heat exchanger ( 3 ) and reheater ( 1 ) with integrated heat exchanger ( 2 ) and upstream drinking water preheating ( 15 ) in tap operation, protection against scalding in the hot water pipe ( 8 ) and circulation pipe ( 9 ) guaranteed ( Fig. 7). 10. The method according to claim 1, 2, 5, 6, 8, characterized in that the described function of the pump ( 4 ), three-way valve ( 5 ) and drinking water mixer ( 7 ) in the circuit variants described also for a pipe in pipe system ( 16 ) is used ( Fig. 8).