Heat pumps
Schelter Heating and Air Inc.
"Providing your shelter with year round comfort!"
Call us today!
Matt Jeremy
404-392-8755 404-406-3088
Main Navigation
Media filters UV lights Steam humidifiers Programmable thermostats
How a Heat Pump works
Definition:
A heat pump uses the atmospheric air to vaporize the liquid refrigerant in the internal compressor of the outdoor heat pump. This hot gas then travels inside through the vapor side of the line set, and into the evaporator coil inside. The air moving over this evaporator coil is then heated by the hot gas inside evaporator coil. This transfer of heat cools the gas and sends it back to the compressor in a liquid state so the process can repeat. During the cooling cycle a heat pump has a reversing valve that controls the directional flow of refrigerant. A heat pump in cooling mode works exactly like a conventional air conditioner.
Defrost cycle:
As outdoor temperatures drop a heat pump starts to lose its volume of hot gas being produced and sent inside to the evaporator coil. The outdoor unit also starts to frost over and has to go into its defrost cycle which turns the fan on top off and switches the system into cooling mode. This heats the refrigerant in the lines drastically and thaws the frost. After 10 minutes or once the defrost temperature sensor gets above the factory set point the system comes back on in heating. During very cold and humid days this could happen several times cutting back on the heat being supplied to the home.
Draw backs:
The result of all this is very high electric bills during the coldest parts of winter. As the heat pump loses heating capacity the electric heat kit is energized more often and for longer periods of time and is very expensive as a primary heat source. The most efficient and effective way to utilize a heat pump or any heating system for that matter is a duel fuel system.
Conclusions:
If you remember one thing about a heat pump remember this. A heat pump doesn't produce heat it just moves heat from one place to another. An electric furnace and a gas furnace produce heat. One through an electric current the other through burning gas to make flames. With a duel fuel system you are limiting the use of gas during mild temperatures and then limiting the use of electric heat kit during cold temperatures.
- The first way is through heat demand. This means that if the thermostat is set 4 or more degrees above the current temperature of the thermostat the heat kit will come on instantly with the heat pump until the heat demand is met.
- The second way is through a staging time. The staging time is different for every thermostat and furnace, but it is normally about 5-8 minutes after the heat demand started for a call of 3 degrees or less than the current temperature. If after this staging time the heat demand has yet to be satisfied the heat kit comes on and helps the rest of the way.
- The third way the heat kit is energized is through defrost demand. When the outdoor unit goes into its defrost cycle it sends a signal into the electric heat kit to turn it on if it isn't already.
- The fourth way is only possible if the thermostat is equipped with an "emergency heat" setting and the emergency heat terminal of the thermostat was hooked up at installation. The emergency heat setting turns only the electric heat kit on and leaves the heat pump off.
Duel fuel thermostat
We maintain a small service area in North Metro Atlanta along the GA 400 corridor in order to respond to calls same day or sometimes next day during the peak seasons. This area consists of Cumming, Dawsonville, Macedonia, Free Home, Sugar Hill, Johns Creek, Milton, Alpharetta, and similar areas of Forsyth county, South Dawson county, East Cherokee county, North Fulton county. and Northwest Gwinnett county.
