DE8710386U1 - Domestic hot water boiler with heat pump operated by a boiler - Google Patents

Description

PATENT ATTORNEY

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Domestic hot water boiler operated by a boiler with

Heat pump

The innovation concerns a domestic water boiler with an arrangement for heating the water in a water tank, which contains passage channels for hot flue gases from a boiler which are arranged between a heat-impermeable casing surrounding the water tank at a distance and the outer surface of the water tank.

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A domestic water boiler of the type described above, which is known from the documents of the German utility model No. 8,634,915, is operated by liquid or gaseous fuels in the following way. When the boiler is used in winter to heat a building or apartments, its burner releases the hot flue gases produced during combustion through a pipe to the hot water boiler, either continuously or at certain intervals. In particular, they enter the lower end of the draft ducts to the space around the water tank and possibly to a draft duct running through the water tank along its central axis, and release their heat in the draft ducts to the domestic water in the water tank. At the upper end of the draft ducts, the flue gases are brought together and directed to the chimney. When the boiler is not in operation in summer, the domestic water is heated by an additional heater located under the water tank, which is also fed with a liquid or gaseous fuel and can produce the same flue gases as the boiler. As in winter operation, the hot flue gases enter directly into the lower end of the above-mentioned passage ducts and heat the water tank of the domestic water boiler.

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While during operation in winter the heat given off to the environment by the hot smoke gases from liquid or gaseous fuels can still be used to heat a room and the floor of the room above _, in summer this heat represents a pure loss and disturbance factor.

The innovation is based on the task of operating the domestic water boiler primarily in summer as an additional heating device

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the environment works.

According to the innovation, this task is solved by the condenser of a refrigeration system operated as a heat pump, which acts as an additional heating device and exchanges heat with the water in the water tank.

In a further development of the innovation, the condenser can protrude as a pipe coil from the bottom of a housing containing the heat pump and be sealed by flanges on the wall of the water tank.

A water heater is known from German patent application No. 2,918,256 in which a heat pump enclosed in a housing is placed on its water tank. A pipe coil forming the condenser of the heat pump protrudes vertically downwards from the horizontal bottom wall of the housing in the form of a straight spiral and enters the water tank of the water heater through an opening in the top wall. It is not clear how an airtight seal between the pipe coil and the top wall can be achieved at this entry point.

The aim of the innovation is to operate the boiler in a particularly energy-efficient manner in summer, i.e. when the boiler is switched off. The passage ducts intended for the hot flue gases, in addition to the heat-impermeable casing that surrounds them, then form good thermal insulation for the hot water in the water tank.

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An example of the innovation is shown in the drawing and is explained in more detail below. It shows

Figure 1 shows the arrangement of the boiler and domestic water boiler, in which a heat pump is used according to the innovation, and

Figure 2 shows a horizontal section through a section of the

capacitor i v?which is indicated in Figure* 1 by arrows I&mdash;I .

Figure 1 briefly explains how the known arrangement works in winter:

A liquid and/or gaseous fuel is burned in a boiler 6, and the hot flue gases are conveyed through a pipe to a hot water boiler with the aid of a flue gas pump 14', the main component of which is a water tank 10. This water tank usually has an inlet 13, an outlet 15 and a circulation connection 16, whereby the inlet 13 can be controlled by a valve 14. A casing 11 of the hot water boiler with a thermal insulation layer 12 is provided at a distance from the outer surface of the water tank 10. Pass-through channels (not shown) are in heat-conducting connection with the outer wall of the water tank 10; the hot flue gases are pressed into their lower end and then driven upwards in them, giving off their heat to the water in the interior 17 of the water tank and heating it. Finally, the colder flue gases enter together via an outlet 8 into the chimney (not shown).

When the boiler 6 is not in operation in summer, a known heat pump 20 is used, the special design of which can also be seen in Figure 1:

It contains a compressor 21 and an evaporator 23 with a fan 22, which draws the outside air through one side 40 of a housing 39 enclosing the heat pump 20 over the evaporator 23.

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(arrows 41) in order to keep it as close to room temperature as possible, and pushes the cooled air into the environment on the opposite side 42 (arrows 43). The compressor 21 and the evaporator 23 are connected by a line 24. A second connection goes from the compressor 21 via an inlet line 31 and a supply nozzle 27 to the inlet of a condenser 25, the outlet of which is connected to the inlet of the evaporator 23 via a discharge nozzle 28 and an outlet line 32. A collector 33, a dryer 34, a sight glass 35 and an expansion valve 36 are also connected to the outlet line 32.

The condenser 25 is designed as a straight heating coil 26 for heat exchange with the water surrounding it, which protrudes vertically downwards from the housing 39 of the heat pump 20 and is let into the water through an opening 29 in the almost horizontal cover wall 30 of the water tank 10. After the condenser 25 has been introduced into the interior 17 of the water tank 10, the opening 29 is closed so tightly with the aid of a flange (not shown) that the necessary sealing of the water tank 10 is ensured even at a water pressure of more than 10 at.

In a brochure from the mail order company "Quelle", which describes a heat pump water heater P 301, suitable sealing flanges are specified for this purpose.

In addition to the condenser of the heat pump 20 designed as a heating coil 26, further heat sources, namely an electric immersion heater 37 and a pipe coil 38, can be arranged within the water to be heated, which is located in the interior 17 of the water tank 10.

Figure 2 shows a detailed cross-section through the heating coil 26. It has an inner tube 44 for a heat-conducting working medium 45 mixed with lubricating oil and, for safety reasons, a jacket tube 46 surrounding the inner tube 44 at a distance 47, whereby a medium 48 that conducts heat well ensures the heat transfer from the working medium 45 into the water to be heated that surrounds the jacket tube 46.

Normally, the burner of the heating boiler 6 is operated intermittently, i.e. it only comes into operation for a limited time, controlled by a thermostat. In the transitional periods, i.e. in spring and autumn, this means that only insufficient quantities of hot flue gases can be supplied by the heating boiler 6 and fed to the water in the water tank 10. Therefore, in such transitional periods, the heating boiler 6 and the heat pump 20 are normally operated together so that the water in the water tank 10 is brought to the temperature that can be set on a thermostat. Consequently, not only the burner of the heating boiler 6 can be switched on and off depending on a temperature, e.g. the temperature outside the building, but also the heat pump 20 and the auxiliary electrical heat sources, namely the immersion heater 37 and the coiled tubing 38, individually or jointly, controlled by a thermostat.

If the burner of the heating boiler 6 is in operation almost without interruption in the severe winter, the heating boiler 6 and the pipe 7 heat up the air in the normally closed room in which the entire arrangement according to the innovation is housed to a considerable extent. The heat pump 10 can then extract the heat from this warm room air and transfer it to the water in the water tank 10. Under these special conditions, the arrangement according to the innovation can be operated in a particularly energy-efficient manner.

Claims (2)

PROTECTION CLAIMS 1. Domestic water boiler with an arrangement for heating the water in a water tank, which contains passage channels for hot flue gases from a heating boiler, which are formed between a heat-impermeable casing surrounding the water tank at a distance and the outer surface of the water tank, and with an additional heating device arranged outside the passage channels in the water tank, characterized in that the condenser (25) of a refrigeration system operated as a heat pump (20) is in heat exchange with the water in the water tank (10) as an additional heating device. 2. Domestic water boiler according to claim 1, characterized in that the condenser (25) projects as a pipe coil (26) from the bottom of a housing (39) containing the heat pump (20) and is sealed by flanges on the wall (30) of the water tank (10). &bull; * · it &bull; * # &igr;*