DE2517610A1 - Central heating system with auxiliary heater - has system of load levels and tariff periods allowing maximum economy - Google Patents

Abstract

A central heating system with heat pump and auxiliary heating in which the heat pump only operates up to a predetermined first external temperature, has heat storage (12, 13) for the heat transfer medium with a flow through heater (10) having several separate loading levels (10a, b, c) which can be connected into circuit operating at a second specified external temperature level between 0 and 20 deg. C by applying low tarif electricity to a load stage (10a) of the flow through heater (10). A series of external temperature and tarif period combinations allows the system to operate economically.

Description

STlEBEL ELTROM GmbH & Co. KG

Apr. 16, 1975 - TSR File 370 / To

Central heating

The invention relates to a central heating system with a heat pump and additional heating, the heat pump only up to a certain level Outside temperature I is in operation.

In the reference H. Rietschels "Textbook of hot and ventilation technology", 13th edition, Berlin / Göttingen / Heidelberg, 1958, page 234, it is mentioned that an uneconomical heat pump operation can be avoided by using the heat pump only numerically predominantly heating days with temperatures above 0 ⁰ C is used and bai lower outside temperatures the heating water heating is partially or completely transferred to a boiler system. Proposals for realizing this idea are not contained in the cited literature reference. In addition, it is extremely uneconomical to keep a boiler system ready all year round, which must be dimensioned to cover the entire maximum heat requirement, and to use it only on a very few days a year.

When designing new heating systems, economic efficiency further with regard to operating and acquisition costs Requirements to be observed. So it is desirable to reduce the connected load of the central heating and a 24-hour base load to ensure over approx. 200 heating days.

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The object of the invention is thus / central heating of the above Kind of propose that works with a heat pump that is only so powerful that the auxiliary heating, in particular an instantaneous water heater, the heat pump to cover the heat demand not only peeled off at very low outside temperatures, but these Supported even at relatively high outside temperatures, and at which the electrical energy consumed is supported favorably during the low tariff period and the high tariff time is distributed.

According to the invention, the central heating works with a memory for a heat transfer medium and with a water heater, which with is provided with several separately switchable power levels,

In the low tariff period, from a certain outside temperature II, which is below 20 ⁰ C and above 0 ⁰ C, a power level of the flow heater with about 1/4 to 3/4 of the total output of the flow heater is switched on,

During the low tariff period, I is below the certain outside temperature the maximum output of the instantaneous water heater switched on,

at an outside temperature III, which is below the outside temperature II and is above the outside temperature I or this is the same, is when the connected load of the heat pump or is reduced Shutdown of the heat pump, a performance level that replaces the reduction in the connected load, both in the off-peak period and

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switched on during the high tariff period and at an outside temperature of IV, which lies between the certain outside temperature II and the certain outside temperature III, is used in the high tariff period and in the Low tariff time heat transfer medium taken from the storage tank.

The invention achieves that above the certain outside temperature II, for example 15 ^° C., only the heat pump works both in the high tariff period and in the low tariff period. For example, it has a connected load of 5 kW. Below the certain outside temperature II, a power level of the instantaneous water heater works in addition to the heat pump. This heats up the storage tank. From an outside temperature IV, for example 5 ⁰ C, hot water from the storage tank is added to the flow from the heating circuit, which is only insufficiently heated by the heat pump, both in the high tariff period and in the low tariff period. If the outside temperature falls below the specific temperature value I, for example O ⁰ C, or -15 ⁰ C, the heat pump is switched off because its operation is no longer economical here. During the high tariff period, a power level of the instantaneous water heater is switched on, the connection value of which corresponds to the connection value of the heat pump. During the low tariff period, the instantaneous water heater works at its full capacity at this outside temperature.

Instead of completely switching off the heat pump, according to the invention, at an outside temperature III, for example

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between 0 and -15 ⁰ C, the reduction in the electrical power consumed at this temperature for physical reasons in addition to the reduction in efficiency can be compensated for by switching on a corresponding power level of the water heater to maintain the desired base load.

Of course, the activation of the heat pump or the Performance levels of the instantaneous water heater in addition to the actual one Heat demand.

A major advantage of the invention is the fact that a Central heating is created, which on the one hand uses the advantages of a heat pump, but on the other hand its heat generation makes sense supplemented by a step-by-step connection of electrical heating. Another advantage is that on the one hand one of the electricity supply companies desired base load is connected to the power grid, but that this is mainly from the heat pump is absorbed and only then by the water heater during the high tariff period is consumed when the outside temperatures are particularly low, at which a heat pump only disproportionately could work at great expense.

It also shows that the nominal connected load of the central heating compared to conventional central heating is reduced by at least 1/3.

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In an embodiment of the invention, the water heater has three Power levels on, with the 1st power level, which is the one when the power is switched off the heat pump switches on whose connected load corresponds. The other two power levels are preferred same size.

A further development of the invention is characterized in that even when the flow temperature of the heat carrier is below a temperature of about 4 5 ⁰ C over a period of time, heat carrier is removed from the memory. So that nichz the heated by the heat pump flow is mixed with water only at an outside temperature IV, for example, 5 ⁰ C, but also suddenly increased heat demand hot water from the reservoir is ensured.

Central heating is particularly easy to install when the heat pump and the water heater as well as the necessary switching and connecting means are integrated in one unit. This also has the advantage of space-saving accommodation.

Further refinements of the invention emerge from the following Description of an execution match. In the drawing show:

Figure 1 shows the water-related structure of a central heating system schematically and

FIG. 2 shows the electrical circuit of the system according to FIG. 1.

A heat pump 1 is connected on the output side to a heat exchanger 2. The heat pump 1 consists in a known manner of an evaporator, a compressor, a condenser and a throttle valve. The heat exchanger 2 is connected to the condenser. A heat transfer medium acts on the evaporator on the inlet side. In the present case, the ambient air, in particular, serves as the heat carrier, which is passed through a channel shown schematically 3 is supplied and discharged via a channel 4.

A return line opens into the heat exchanger 2 on the outlet side 5 of the central heating system- It is connected to a feed line via a solenoid valve 6, a backflow preventer 7 and a feed pump 8 9 connected.

There is also a water heater that can be switched in several stages 10 provided. On the input side, this is via a solenoid valve 11 on the return line 5 and is connected to the output of two series-connected Storage tanks 12 and 13 connected. On the output side, the water heater 10 is connected to the via a circulation pump 14 Storage tank 13 connected. Between the pump 14 and the pump 8 is a connection via a solenoid valve 15 and a solenoid valve 16 made with upstream backflow preventer 17.

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In the flow line 9 and the return line 5 is how Usually a mixer 18 is provided.

The structure and installation of the central heating are simplified in that the essential components 1, 2, 6-8, 10, 11, 14-17, are installed on a carrier 19.

In FIG. 2, the electrical actuation means of the components described are provided with the same reference numerals as those in FIG. The circuit is between the ground terminal Mp and the phase R of the alternating current network. During the low tariff period, the mains voltage is also applied to pole RN. An outside temperature sensor is provided, via which four contacts 20, 21, 22 and 23 are closed by means of a controller (not shown in detail) according to the respective outside temperature. From an outside temperature of, for example, 15 ^° C., contact 21 closes, when the temperature drops further to 5 ^° C., contact 20 and, at 0 ^° C., contacts 22 and 23. The water heater is provided with three power levels 10a, 10b and 10c. The power stage 10a is in series with the contact 21. The power stage 10b is in series with the contact 22. The contact 23 is followed by a winding 24 of a relay which has two break contacts 25 and 26 and three make contacts 27, 28 and 29. The contact 25 is in front of the compressor of the heat pump -1 and the solenoid valve 6. The contact

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is located between the Uralauf pump 14 and the one connected in parallel Solenoid valve 11 and the contact 21. The contact 27 is followed by the power stage 10c of the water heater. Contact 28 is on in front of the circulation pump 14 and the solenoid valve 11. The contact 29 is in series with the solenoid valve 16.

A temperature sensor is provided in the flow line 9, which closes a contact 30 when the flow temperature falls below ^{4 5 ° C.} The contact 30 is located in front of the winding 31 of a further relay which has a contact 32. This contact is parallel to contact 20. The parallel connection of contact 20 and contact 32 is followed by the solenoid valve 15.

In addition, phase R is followed by a switch-on contact 33 and phase RN is followed by a switch-on contact 34. At contact 33 are the feed pump 8, the contact 25, the contact 20, the contact 30, the contact 32, the contact 23 and the contacts to 29. The contacts 21 and 22 are located on the switch-on contact 34.

The described arrangement works as follows when there is a need for heat:

1. At an outside temperature above 15 ⁰ C, the contacts 20 to 23 are open. The heat pump 1 is working. The solenoid valve 6 is open and the feed pump 8 is running. This applies to both the high tariff period and the low tariff period. 6Q8 84 5 / Q403

2. If the outside temperature is between 15 ⁰ C and 5 ⁰ C, nothing changes in the switching status described under item 1 during the high tariff period. During the low tariff period, the power stage 10a and the circulating pump 14 via the closed contact 26 are also switched on and the solenoid valve 11 is opened. The power stage 10a of the flow heater 10 now heats the storage containers 12, 13.

3. At a temperature between 5 ^° C. and 0 ^° C., the contact 20 also closes. This opens the solenoid valve 15. Hot water from the storage tanks 12, 13 is now added to the water heated by the heat pump 1. During the low tariff period, the power stage 10a and the circulation pump 14 work as described under item 2.

4. When the outside temperature is below 0 ⁰ C

In addition to contacts 20 and 21, contacts and 23 are closed. By closing contact 23 contacts 25 and 2 6 are opened via relay winding 24 and contacts 27, 28 and 2 9 are closed. the This switches off the heat pump 1 and the solenoid valve 6

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closes. It is now - even in the high tariff period - instead the heat pump 1 is connected to the power stage 10c, which has the same electrical connection value as the heat pump 1 having. The solenoid valves 11 and 16 are the same as the solenoid valve 15 open. Pumps 8 and 14 are running. In the low tariff period, the closed contacts 21 and 22 are the power levels 10a and ICb also switched on. The entire heating takes place by means of the flow heater.

Regardless of the outside temperature of the contact 30, when the temperature of supply water falls below 4 5 ⁰ C, closed. If this low flow temperature lasts for some time, for example more than 5 minutes, then the contact 32 closes, so that the solenoid valve. 15 is opened and hot water from the storage tanks is added to the flow.

The following is a general estimate of the connection relationships:

If one assumes, for example, a 24-hour heating requirement 3 60 kWh off, then the heat pump needs a performance figure of 3 without taking into account of the overall efficiency of the heat pump an electrical energy of 1 20 kWh, the heat pump must therefore have a connected load of Have 5 kW. To achieve a base load during the heating season

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the output level 10c, which works at high tariff times below 0 ⁰ C instead of a heat pump, also has an output of 5 kW. If a heat requirement of 3 60 kWh below 0 ⁰ C has to be covered by the water heater alone, then after deducting the 24-hour energy of power level 10c, another 240 kWh must be applied in storage mode. Assuming an 8-hour low tariff period, this means that the output levels 10a and 10b must have a total output of 30 kW. Each of the power levels 10a and 10b preferably has half this power, that is to say 15 kW. In total, the water heater has a connected load of 35 kW.

If you compare this connection value of 3 5 kW with the connection value, who would have to have a central heating system that only works during an 8-hour low tariff period (45 kW), then it follows that the connected load in the central heating system according to the invention is reduced by about 1/3.

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Claims (13)

Claims / i. j Central heating with heat pump and additional heating, in which the heat pump is only in operation up to a certain outside temperature I, characterized in that the central heating works with a memory (12, T3) for a heat transfer medium and with a water heater (10) that works with several separately switchable power levels (10a, 10b, 1Oc) is provided that in the low tariff period from a certain outside temperature II, which is between 20 ⁰ C and above 0 ⁰ C, a power level (10a) of the water heater (10) with about 1 / 4 to 3/4 of the total output of the water heater (10) is switched on, that the maximum output of the water heater (10) is switched on during the low tariff period below the certain outside temperature I, that at a certain outside temperature III, below the outside temperature II and above outside temperature I is or is the same, when the connected load of the heat pump (1) is reduced or when the heat pump (1) is switched off e the reduction in the connected load, which is a substitute power level (10c), is switched on both in the low tariff period and in the high tariff period and that at an outside temperature IV, which is between the certain outside temperature II and the certain outside 6 0 9 8 k R / Π U 0 3 2 b 1 V 6 1Ü temperature III, in the high tariff period and in
the low tariff time heat transfer medium is taken from the memory (12, 13). 2. Central heating according to claim 1, characterized in that the outside temperature I is 0 ⁰ C. 3. Central heating according to claim 1, characterized geke η nz eich ne t that the outside temperature I is -15 ⁰ C. 4. Central heating according to claim 3, characterized in that the outside temperature IH is 0 ⁰ C. 5. Central heating according to one of the preceding claims, characterized in that the outside temperature II is +15 ⁰ C. 6. Central heating according to one of the preceding claims, characterized in that the outside temperature IV is 5 ⁰ C. ύ U) 3 7. Central heating according to one of the preceding claims, characterized in that the power level (1Oa) switched at outside temperature II is about half of the total output. 8. Central heating according to one of the preceding claims, characterized in that in the low tariff period all power levels (10a, 10b, 10c) are switched on below outside temperature I. 9. Central heating according to one of the preceding claims, characterized in that the water heater (10} has three power levels (10a, 10b, 10c), the 1st power level (10c) being the one when it is switched off the heat pump switches on whose connected load corresponds. 10. Central heating according to claim 9, characterized in that the other two power levels (10a, 10b) are the same size. 11. Central heating according to one of the preceding claims, characterized in that the 1st power level is divided into two performance levels, whose f. η 'i η / _t S / 0403 one is switched on when the power consumed by the heat pump is reduced and the other is also switched on when the heat pump is switched off. 12. Central heating according to one of the preceding claims, characterized in that even when the flow temperature of the heat carrier falls ^{below about 4 5 0} C over a certain period of time, heat carrier is removed from the memory (12, 13). 13. Central heating, in particular according to one of the preceding claims, characterized marked eichn e t that the heat pump (1) and the water heater (10) as well as the necessary switching and connecting means (2, 6, 7, 8, 11, 14, 15, 16, 17) are integrated in one unit. (i 0 9 ¹ H 4! / 0 U 0 3