A very high efficiency gas furnace may be 95% efficient at burning gas and delivering heat to your home. But a heat pump, which is an air conditioner running in reverse using electricity, can be up to 300% efficient!
You should ask, "How can it be more than 100% efficient?" Good question: and the answer is simple. A heat pump isn't producing heat like a gas or oil combustion appliance; it's moving heat. An air conditioner moves heat from inside to outside, and a heat pump, which is an air conditioner that can run backwards, moves heat from outside to inside.
In Northern climates you may wonder how that's possible if it's cold outside. But a high efficiency heat pump can do a great job down to about 38° F outside. We can install a hybrid system (see our video) for the greatest efficiency. When it's too cold out for the heat pump, a high efficiency gas furnace takes over.
You'll be living with your heating system for 20 years or so, and it is very important to install one that just sips energy, instead of chugging it!
Call Dr. Energy Saver for a Free Estimate for heat pump heating in Charlottesville, Fredericksburg, Spotsylvania, Jeffersonton, Earlysville, Culpepper, Madison, Keswick, Rixeyville, Rapidan, Palmyra, Stanardsville, Locust Grove, and the neighboring areas!
No doubt about it: Heat pumps are pretty amazing devices. On a hot summer day, a heat pump moves indoor heat to the outdoors. In cold weather, the cycle reverses and the heat pump somehow finds heat outdoors that can be "pumped" inside. Understanding the basics of heat pump operation can help you make important decisions about improving your home's energy efficiency.
A heat pump depends on the unique properties of refrigerant compounds (such as Freon™ and Puron™) that are pumped through evaporative and condensing cycles to absorb and release heat. A refrigerant's ability to boil at a relatively low temperature helps to facilitate the heat transfer process.
The same evaporative and condensing processes take place in all types of heat pumps. But ground-source heat pumps (aka geothermal heat pumps) take advantage of the fairly consistent temperature of the ground or the water in a well or lake. While the temperature of the earth at a depth of 6ft. or more remains around 50-65°F all year round, air temperature can go from below freezing to 90°F or more. Because they have more favorable operating temperatures, ground-source heat pumps are more efficient than air-source heat pumps.
To understand how heat pumps work, let's look at a typical air-source heat pump:
The heating system cycle starts outside the house, as liquid refrigerant is pumped into evaporator coils that are surrounded by fins to promote heat transfer. A fan in the exterior module pulls air through the coils, producing sufficient warming to turn the liquid refrigerant into vapor. When this phase change occurs, heat is absorbed (The same phase change effect makes us feel cool when sweat evaporates from our bodies.)
The vapor now gets pumped through a compressor, which increases the temperature of the gas by putting it under pressure. (Did you ever notice how hot a bicycle pump gets when your pumping action puts air under pressure?) The hot refrigerant vapor moves indoors to heating coils located in the HVAC system's air handler. As the refrigerant gives up its heat to the interior air and is allowed to expand, it condenses back into a liquid and is pumped outside to repeat the cycle.
The path of the refrigerant reverses to move indoor heat outside. Now the indoor coil acts as the evaporator (cooling coil), enabling the refrigerant to pick up interior heat as it vaporizes. After being pumped through the compressor and into the outdoor coil, the indoor heat is "dumped" outside and the refrigerant expands and cools before returning to the interior coil.
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