Heat Pumps

High Efficiency Heat Pumps from Trane

Heat pumps use electricity to distribute heat evenly throughout your home. Instead of burning fossil fuel like a furnace a heat pump captures the ambient heat from outdoor air and moves it into your home. High efficiency heat pumps from Trane can heat your home in the winter or cool it in the summer. Trane's reliability testing on is directed to exceed industry standards. For example:

• While industry standards order testing a heat pump coil to just 250,000 stress cycles, the Climatuff coil has successfully endured more than 3 million cycles to assure years of trouble-free service.
• The coils of our heat pumps endure a 2,000-hour salt spray test to check corrosion – which is twice the 1,000-hour industry standard.
• Our heat pumps also undergo 2,688 hours of continuous testing in the Systems Extreme Environmental Test (SEET) lab. Testing that simulates five years of wear and tear in extreme conditions in just 16 weeks.
• During assembly, each heat pump is put through an air pressure test at 350 PSIG, a short circuit test and a refrigerant leak test with mass spectrometer and halogen detection devices.
• After assembly, run tests are conducted on all heat pump units to ensure proper operation prior to packaging and shipping.

How Does an Air-source Heat Pump Work?

The air-source heat pump has three cycles:

·        the heating cycle

·        the cooling cycle

The Heating Cycle

During the heating cycle, heat is extracted from outdoor air and pumped indoors.

First, the liquid refrigerant passes through the expansion device, changing to a low-pressure liquid–vapour mixture. It then goes to the outdoor coil, which acts as the evaporator coil. The liquid refrigerant absorbs heat from the outdoor air and boils, becoming a low-temperature vapour.

The reversing valve sends this vapour to the accumulator, which collects any remaining liquid before the vapour passes to the compressor. The vapour is then compressed, reducing its volume and causing it to heat up.

Finally, the reversing valve sends the gas, which is now hot, to the indoor coil, which acts as the condenser. The heat from the hot gas is transferred to the indoor air, causing the refrigerant to condense into a liquid. This liquid returns to the expansion device and the cycle is repeated.

The ability of the heat pump to transfer heat from the outside air to the house depends on the outdoor temperature. As this temperature drops, so does the ability of the heat pump to absorb heat (the unit's capacity).

At the outdoor ambient balance point temperature, the heat pump's capacity is equal to the heat loss of the house. Below this outdoor ambient temperature, the heat pump cannot supply all the heat required to keep the living space comfortable, and supplementary heaters must be used.

When the heat pump is operating in the heating mode without any supplementary heat, the air leaving it will be cooler than air leaving a furnace. Furnaces generally deliver air to the living space at between 55°C and 60°C. Heat pumps provide air in larger quantities at about 29°C to 43°C.

The Cooling Cycle

The heating cycle is reversed to cool the house during the summer. The unit takes heat out of the indoor air and transfers it outside.

As in the heating cycle, the liquid refrigerant passes through the expansion device, changing to a low pressure liquid–vapour mixture. It then goes to the indoor coil, which acts as the evaporator. The liquid refrigerant absorbs heat from the indoor air and boils, becoming a low-temperature vapour.

The reversing valve sends this vapour to the accumulator, which collects any remaining liquid, and then to the compressor. The vapour is then compressed. As its volume is reduced, it heats up.

Finally, the reversing valve sends the heated gas to the outdoor coil, which acts as the condenser. The heat from the gas is transferred to the outdoor air, causing the refrigerant to condense into a liquid. This liquid returns to the expansion device and the cycle is repeated.

During the cooling cycle, the heat pump also dehumidifies the indoor air. Moisture in the air passing over the indoor coil condenses on the coil's surface and is collected in a pan at the bottom of the coil. A condensate drain connects this pan to the house drain.