> > > >

1947-48 Theatre Catalog, 6th Edition, Page 431 (417)

1947-48 Theatre Catalog, 6th Edition
1947-48 Theatre Catalog
1947-48 Theatre Catalog, 6th Edition, Page 431
Page 431

1947-48 Theatre Catalog, 6th Edition, Page 431


As stated, the heat pump is essentially an enlarged application of the ordinary electric refrigerator.

Mechanical Equipment

Expressed in non-technical language, it consists of a closed system through which a refrigerant, such as Freon, is circulated. The main parts of the system consist of an evaporator, where the cold

liquid refrigerant absorbs heat from the;

surrounding space and, in so doing, changes from a liquid to a gas; that is, evaporates. It then passes through a compressor, where the refrigerant, now in gas form, is compressed, which greatly raises its temperature. Then it goes through pipes or tubing to a condenser, where the now very hot gas is condensed back to a liquid state and gives up the heat absorbed in the evaporator plus the additional heat created by compression. The mechanism is run by an electric motor, which drives the compressor, and is automatically controlled by thermostats. The entire unit is enclosed in a suitable cabinet measuring approximately 3 feet Wide by 6 feet long and 6 feet high.

Types of Systems

It is obvious, of course, that there must be some exterior source of heat that can be constantly drawn on. This source of heat is in the outside air, in bodies of water, such as lakes or rivers, in ground water, such as wells, and in the earth itself. Two basic types of heat pumps have been developed, one which absorbs heat from the outside atmosphere, called an air-to-air unit, and one which obtains heat from the ground, or from ground water, called a ground or water-to-air design.

Air-to-Air SystemseThe application of the air-toeair system lends itself most satisfactorily to locations where the outside temperatures does not fall much below 40 degrees; that is in the southwest and southern areas of the country. In this type of unit, air is drawn in from outside the house, passed over the evaporator where it gives up a certain number of Btuis of heat, and is expelled outside again at a reduced temperature. The cycle is constant (while the heat pump is in operation) and consequently a great many Btuls of heat are obtained. For example, even when air is at a temperature of 0 degrees it contains 73 Btu. of heat in every pound.

Ground-to-Air Systemseln the groundto-air design, one method is ta bury a coil of copper, or other suitable metal tubing, in the earth outside the house. The refrigerant is circulated through this tubing, absorbing ground heat, and then it passes through the compressor in the heat pump located in the cellar, and on through the cycle described above. Another method is to circulate water through a closed pipe sunk deep in the ground. The water absorbs ground heat which in turn is passed on to the refrigerant in the heat pump.

The ground-to-air job appears particularly suited to the colder sections of the country, since ground temperatures range from 40 to 50 degrees even in the northern part of the country, and vary within a range of only 1 or 2 degrees from season to season.


THE MARVAIR is a ground-to-air system, utilizing the heat stored in the earth, obtained by pumping water through submerged piping. A closed U-shaped pipe circuit is enclosed in a 4' to 5-inch bore sunk some 200 feet into the ground below the operating water line. Picture, courtesy oi Muncie Gear Works, shows a cut-away View of the compressor side of the unit. Pump is in the right-hand side.

(In Switzerland, a number of waterto-water heat pumps have been in successful operation for many years, where large supplies of lake water are available as a source of heat, and other fuel costs are relatively high.)

In both systems, heat is transferred from the condenser to the interior air,

which is circulated through the house in the usual manner. In summer, for cooling purposes, the heat pump automatically reverses itself and absorbs heat from the air within the house, expelling it outdoors. The heat pump can also be operated in conjunction with a hot-water heating system although this would not

INSTALLED IN A HOME, the Marvair unit is shown in association with the air ducts. In one such installation the total electric input for a heating season was 8,825 kilowatt hours to keep the place at 78 degrees night and day. Installation costs approximated $1,650 tor the 3-hp. unit or $2,350 for the 5-hp. one, both figures including the well installation. (Photo courtesy Muncie Gear Works.)
1947-48 Theatre Catalog, 6th Edition, Page 431