DE8616086U1 - Central mixed water preparation system with recirculation - Google Patents

Description

Friedrich Grohe Arraaturenfabrik GmbH & Co, GRP - 634

Central mixed water preparation system with recirculation

The invention relates to a central mixed water preparation device with a connection to the cold water supply network, a heater for producing hot water, a temperature-controlled mixing valve device and a circulation and recirculation device with return lines for mixed water into the heater and into the mixing chamber of the mixing valve device or into the cold water supply line.

The purpose of this device is to provide mixed water at the taps provided in the pipeline network at a temperature corresponding to the setpoint, so that mixed water at the appropriate temperature is immediately available when the water is tapped.

In the known mixed water preparation systems, a so-called central thermostat is used as a mixing valve device with return of the mixed water via fixed return cross-sections.

cuts in the heater and in the central thermostat. In terms of control technology, such a device can be described as a feedback dead-time system, which has undesirable dynamic properties.

The invention is based on the object of improving the known mixed water preparation device with simple means.

10

This object is achieved according to the invention in that a buffer element in the form of a suitably dimensioned container is provided in the circulation circuit of the mixed water. By using the buffer element, the mixed water preparation device can be dynamically/thermally decoupled using simple means, thereby improving the dynamic behavior of the circulation system.
Further embodiments of the invention are specified in claims 2 to 6.

The container of the buffer element can be designed in such a way that it corresponds to about one third of the

The buffer element is designed to be the same as the volume of water flowing through it per minute. On a test bench, such a dimensioning led to a drastic reduction in the temperature peak, namely to 1/5 of the original value. The buffer element can be installed upstream or downstream of the taps or can also be installed twice. The purpose of the buffer is in any case to limit and to reduce the amplitude of temperature deviations from the setpoint temperature caused by faults, which cannot be compensated for in the control dead time of the mixing valve device or the central thermostat.

smooth. With an upstream buffer element in front of the tapping points, the advantage can be achieved that

The

in pure tapping operation, where circulation is prevented, temperature deviation peaks are smoothed out, but at the same time the running time to the tapping points is increased*

Advantageously, the container wall of the buffer element can be provided with insulation against heat transfer.

An embodiment of the invention is shown in the drawing in SCHE-

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Figure 1 is a circuit diagram of a Figure 2 is a buffer element of a central mixed water preparation plant

The mixed water preparation device is connected to the cold water supply network 1, with a first branch of the cold water being fed to a mixing valve device 3 via a backflow preventer as a cold water supply line 11, while a second branch feeds cold water to a heater 2 for generating hot water via a backflow preventer 7. The heater 2 is also connected to the mixing valve device 3 via a hot water line 21, in which a tempered mixed water that can be determined using a temperature pre-selector is generated. The mixed water is fed into a mixed water line 31, which is designed as a circular line and on which individual taps 4 are provided. Downstream behind the taps 4, a circulation pump 5 is provided in the mixed water line 31, which circulates the water present in the mixed water line 31 or the circulation line. Downstream behind the circulation pump 5, the mixed water line branches into a return line 51 to the heater 2 and a return line 52 to the mixing valve device 3. Instead of the direct return to the mixing valve device 3, ■ the circulating mixed water can alternatively be fed into the cold water supply line 11, as |

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it is shown in the drawing with the dashed line 53. In addition, the heat loss occurring in the circulation circuit through the piping system is indicated with a block 32.

To improve the control behavior, a buffer element 6 is introduced into the return line 52 upstream of the mixing valve device 3. The buffer element 6 is designed as an insulated container and is connected to the return line 52 with a connecting piece.

In order to ensure that the water supplied in the buffer element 6 is mixed as completely as possible with the water already present in the buffer element 6, the connection piece for the incoming mixed water is introduced approximately coaxially into the buffer element 6 with a pipe section 61 perforated in the side wall.

The volume of the buffer element 6 is designed so that it can hold about 1/3 of the mixed water circulating per minute. Together with the water volume of the rest of the circulation system, as has been verified by tests, the thermal buffer element 6 can significantly limit temperature deviations from the setpoint caused by faults, which cannot be compensated for by the mixing valve device 3 during the control dead time, and in particular smooth out temperature jumps.

Claims (6)

J ·· Il · t ·> -S- Friedrich Grohe Armaturenfabrik GmbH & Co. GRP - 634 CLAIMS 1. Central mixed water preparation device with a connection to the cold water supply network (1), a ■heater (2) for hot water production, a temperature-controlled mixing valve device (3) and a circulation and recirculation device with return lines (51,52) for mixed water into the heater (2) and into the mixing chamber of the mixing valve device (3) or into the cold water supply line (1:), characterized in that in the circulation circuit of the mixed water a buffer element (6) in Form of a suitably dimensioned container is provided in which the supplied water is mixed with the water present in the buffer element (6). 2. Mixing water preparation device according to claim 1, characterized in that the buffer element (6) has a volume of approximately one third of the amount of mixed water flowing through the buffer element (6) in one minute. Mixing water preparation device according to claim 1 or 2, characterized in that the buffer element (6) is arranged in the return line (52) to the mixing valve device (5). 4. Mixed water preparation device according to claims 1 or 2, characterized in that the buffer element (6) is arranged upstream of the taps (4) in the mixed water line. 5. Mixing water preparation system according to at least one of claims 1 to 4, characterized in that a first buffer element is arranged upstream of the taps (4) in the mixed water line (31) and a second buffer element is arranged in the return line (52) to the mixing valve device (3). 6. Mixing water preparation system according to at least one of claims 1 to 5, characterized in that the buffer element (6) or the buffer elements are insulated against heat exchange with the outside area. «I 4 · I ft 4 4 I · * I 44 · < * 4 « 4 t 4 1 *· Il l< I < r Il IM I I · It Il · &igr; Il (I