GB2334089A

GB2334089A - Heating and cooling system for a building

Info

Publication number: GB2334089A
Application number: GB9802319A
Authority: GB
Inventors: Terence Robert Seward; Peter Geoffrey Heaton
Original assignee: Temperature Ltd
Current assignee: Temperature Ltd
Priority date: 1998-02-03
Filing date: 1998-02-03
Publication date: 1999-08-11
Also published as: GB9802319D0

Abstract

A building temperature control system 10 comprises radiators 19 connected to a heat exchanger 18 of a heat pump 12 which also has a second heat exchanger 14 connected to a water loop 16 in the ground. In the winter heat pump 12 provides warm water to radiators 19. On warm summer days, valves 31, 32 switch heat pump 12 out of the system, and cool water is circulated from loop 16 to radiators 19, which now serve to cool the building. On hot summer days, heat pump 12 is operated to chill the building water loop. A heat exchanger 17 connects the ground loop to a second heat pump 22 which is used to heat water in a hot water tank 27 all the year round. Heat exchanger 24 of the second heat pump may have its own ground water loop (46).

Description

Heating and Cooling Systems The present invention relates to heating and cooling systems of the type used to condition the temperature within buildings.

Typically, buildings require heating in winter and cooling in summer. In both cases, the ultimate source of the energy required for the temperature control is a fossil fuel, viz oil, gas or coal. In ecological terms this is disadvantageous and it is also expensive.

Furthermore, existing heating and cooling systems employ relatively bulky components which occupy valuable floor space.

The present invention seeks to overcome or reduce one or more of the above problems.

According to the present invention, there is provided a building temperature control system comprising a heat pump, comprising a heat pump comprising first and second liquid to refrigerant heat exchangers, the first exchanger being in a first circulating loop with building load heat exchangers and the second heat exchanger being in a second circulating loop incorporating heat exchanging means embedded in the ground, wherein means are provided for switching the heat pump out of the loops to form a third circulating loop comprising the building load heat exchangers and the heat exchanging means embedded in the ground.

Preferably a liquid to liquid heat exchanger is also provided in the second loop to link it to a fourth circulating loop. The fourth circulating loop may also incorporate a first liquid to refrigerant heat exchanger of a second heat pump, a second liquid to refrigerant heat exchanger of which is in a fifth circulating loop incorporating a further heating load.

The fourth circulating loop may also incorporate respective heat exchanging means embedded in the ground.

The liquid in the heat exchangers is preferably water.

The building load exchangers may comprise radiators or other space heaters and the further heating load may comprise a cylinder for supplying hot water.

A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, of which: Fig. 1 shows a building temperature control system configured to operate in a space heating mode or in a space "active cooling" mode; and Fig. 2 shows the control system of Fig. 1 configured to operate in a space "free cooling" mode.

Referring to the drawings, Fig. 1 is a schematic diagram of a system 10 for controlling the temperature of a building 11. The system comprises a water-to-water heat pump 12 having a water-to-refrigerant heat exchanger 14 connected to a closed circuit water loop 16 in the ground, and a second water-to-refrigerant heat exchanger 18 connected to the heat load in the building 11 via heat exchangers 19 within the building.

A second water-to-water heat pump 22 provides hot water to a tank or cylinder 27. The rating of pump 22 is typically 2 kw whereas that of the first heat pump is typically 6 kw.

Heat pump 22 has a water-to-refrigerant heat exchanger 28 connected to the heat exchanger 29 within the hot water tank 27 and a second water-to-refrigerant heat exchanger 24 connected to a water-to-water heat exchanger 17, so as to exchange heat with the closed circuit loop 16 but situated above ground level 40.

The configuration illustrated in Fig. 1 is for use in winter when the building 11 requires heating. Heat pump 12 provides warm water to the building heat exchangers 19.

The other side 14 of the heat pump refrigerant circuit acts as an evaporator and circulates chilled water through the ground loop 16.

Heat pump 22 provides hot water to the hot water tank 27 all year round, and the other side 24 of its refrigerant circuit acts as an evaporator and circulates water through the heat exchanger 17.

Turning now to Fig. 2, there is shown a configuration of the system 10 for use in summer on warm days. The change in configuration is obtained by switching over three-way valves 31,32. Free cooling is achieved in the building by circulating water at ground temperature from the ground water loop 16 through the heat exchangers 19. Heat pump 12 is inoperative in this mode. Being at a lower temperature than the building the water provides a cooling effect to the spaces in the building. Since hot water is required in tank 27 all year round, the heat pump 22 provides cold water to heat exchanger 17, thus assisting in cooling the ground loop 16.

The above-described system has the advantage of being highly energy efficient utilising the properties of the ground to provide heating and cooling effects. Accordingly, it reduces requirements for fossil fuels. Furthermore, it offers effectively free cooling to the building in summer. The heat pumps used have high coefficients of performance to provide heat spacing and to heat the water. The long stretches of piping used contain water which is relatively easy to handle. The ground water loops 16 used have a well developed technology. They are described, for example, in "Ground-Source Heat Pumps" by Stephen P. Kavanaugh and Kevin Rafferty, published by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. Since part of the system is buried in the ground, there is a saving of space above ground in the building.

Various modifications may be made to the above-described system. For example, on hot summer days the configuration of claim 1 can be modified to provide space "active" cooling. Here heat pump 12 is operated to chill the water loop through the building heat exchangers 19 to provide a space cooling effect. The water passing through the other side 14 of heat pump 12 is now heated; as this water circulates it is cooled again as it passes through heat exchanger 17 and ground loop 16. This arrangement has the advantage of providing a strong cooling effect when required.

In another modification, side 24 of the heat exchanger 22 is provided with a respective ground loop 46 which can be switched in as desired by means of three-way valve 42. With ground loop 46 present, heat exchanger 17 and associated valve 42 can be omitted if desired.

One or more of the following modifications may also be incorporated: a) Underfloor heating pipes which can be utilised also at the ceiling level for the cooling cycle. b) Fan coil units in the spaces with separate heating and cooling fin and tube coils. c) A central ventilation unit providing heating and cooling of intake air by provision of fin and tube coils within and ducted through the building.

Claims

CLAIMS 1. A building temperature control system comprising a heat pump comprising first and second liquid to refrigerant heat exchangers, the first exchanger being in a first circulating loop with building load heat exchangers and the second heat exchanger being in a second circulating loop incorporating heat exchanging means embedded in the ground, wherein means are provided for switching the heat pump out of the loops to form a third circulating loop comprising the building load heat exchangers and the heat exchanging means embedded in the ground.
2. A system according to claim 1, wherein a liquid to liquid heat exchanger is also provided in the second loop to link it to a fourth circulating loop.
3. A system according to claim 2, wherein the fourth circulating loop incorporates a first liquid to refrigerant heat exchanger of a second heat pump, a second liquid to refrigerant hear exchanger of which is in a fifth circulating loop incorporating a further heating load.
4. A system according to claim 3, wherein the building load heat exchangers comprises space heating means and the further heating load comprises hot water supply means.
5. A system according to any of claims 2 to 4, wherein the fourth circulating loop incorporates respective heat exchanging means embedded in the ground.
6. A system according to any preceding claim wherein the switching means comprises two three-way valves.
7. A system according to any preceding claim wherein the liquid is water.
8. A building temperature control system substantially as herein described with reference to the accompanying drawings.
9. A method of controlling the temperature of a building using a system according to any preceding claim.