Heat pumps can be used for heating and cooling. Less equipment is needed for a combined unit. Rooftop systems for heating and cooling were first developed for a flat roof and commercial structures. Such structures are supermarkets and office buildings.
There are three types of roof heat pumps:
Heating only.
Cooling only.
Heating and cooling.
In economic systems as they are factory assembled and tested. They are also easily installed once raised at the site. There are some disadvantages to rooftop systems. The roof must be strong enough to carry the extra weight. Holes can develop leaks. Units must be designed for ease of maintenance even in very cold or bad weather. They are also exposed to winds, which can affect their operation. You must have the instruments and expendable materials for the roof. The equipment must be adequate to service the unit in any weather conditions.
Fig. 24-81 shows a typical roof unit, used for heating and cooling. Another building is shown in Figure 24-82.
Many commercial rooms are fully equipped with factory installation of heating units.
On the roof of the gas furnaces typically use electrical ignition system. This is because gas pilot flame tend to blow due to heavy winds and gusts. These units completely from the weather, as they are subject to all kinds of weather. Door for inspection are intended to ensure safe operation under high wind conditions. Fig. 24-84 is a graphical picture refrigerating machines on the roof of the block.
Roof air conditioners sometimes on liquid fuel. Fuel is stored in an underground tank. Lift the pump draws butter second, smaller capacity. This tank can be on the same level or slightly lower than in the oil burner. Under no circumstances should the tank more than 10 feet. (3 m) below the burner.
Electric heat can also be used in roof air conditioners. Electrical heating elements partially removed from the housing. Heating elements are located in 20 kW 40 kW 60 kW of power. Heating elements carefully guarded ceramic insulators. The scheme has fuses fuses and thermal cutouts. Air dampers. Sensitive elements in the mixed-duct engine control, which works in these shock-absorbers:
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