Today's Most Energy Efficient Heating and Cooling System
In this area of the country, home heating and cooling for a comfortable environment usually requires more energy than all other home energy needs combined. For that reason, the selection of a heating and cooling system that is energy efficient is a very important decision for all homeowners. This decision is even more critical because of unpredictable energy costs in the years ahead.
Whether you are building a new home or replacing a heating and cooling system in your present home, the all-season electric heat pump may be your most cost effective option and the option which provides you with the most comfort.
This web page is designed to provide easy-to-understand information about heat pumps -how they work and how they can benefit you in both comfort and energy savings.
The right time to investigate the advantages of the all-season electric heat pump is any time you plan to build or remodel or when your central air conditioner or furnace gives you reason to believe it needs replacing. The information in this booklet can help you make the right decision.
How the Heat Pump Works
The idea of a single machine that both heats and cools your home is puzzling to many people. The name just doesn't seem to fit a device that cools a home in the summer. Many people don't have the least idea how a heat pump works.
It may be easy to understand if we use a familiar example - like the window air conditioner. Think about how you feel comfort from a window air conditioner's cooling breeze when you're inside. You go outside, walk past the same unit and get a blast of hot air in the face. The same machine - blowing cold air into the room while at the same time blowing hot air outside.
If you turned it around, it would blow hot air into the room and cold air outside.
The heat pump manufacturers use this same principle but they do it better. Instead of turning the whole unit around, they simply reverse the flow of the refrigerant. This works better and it can be done with the flick of a switch - or a thermostat.
It's as simple as that. You can let the thermostat decide whether to heat or to cool. You don't have to decide when to turn the heat off in the spring. You can even heat in the morning and cool in the afternoon.
Why is the Heat Pump Such a Good Deal?
Converting one form of energy to another form, without losing in the process, is 100% efficiency. For example, if you convert the energy in gas to heat energy, some of the efficiency is lost because part of the heat goes up the flue and is vented outside with the carbon monoxide.
The electric resistance furnace is 100% efficient because there are no waste gases or by-products given off in the conversion from electrical energy to heat energy. At current prices, however, natural gas costs less to produce the same amount of heat energy.
The heat pump works differently, though. It doesn't play by the same rules. The heat pump delivers more units of heat energy than it consumes in electric energy.
How is this possible? The heat pump doesn't convert one kind of energy to another like the gas or electric furnace. It uses electric energy to move, or pump, heat in the air from one place to another. You're now wondering how much heat is in the air at 20 degrees F. There's plenty.
You probably learned in school science class that there's some heat in air all the way down to minus 373 degrees Celsius. That's about minus 450 degrees Fahrenheit. In fact, at 32 degrees F, there's still about 85% of the heat that's available at 100 degrees F.
In the summer, a heat pump is nothing more than a conventional air conditioner. In the winter, however, the heat pump's extra valves and controls come into play. The flow of refrigerant is reversed, and the heat pump starts heating your home instead of cooling it.
In the heating mode, the heat pump is extremely efficient at moderate temperatures, often delivering three units of heat for each unit of electric energy. Or in other words, 300% efficiency. The efficiency declines as the temperature drops, but the modern heat pump is still efficient at low temperatures. Even under severe conditions, like minus 10 degrees F, it still delivers more than one and one-half units of heat for each unit of electricity used. That's an efficiency story that no other system can equal. And the heat pump does it in the home without fuel or flame. Just pure, clean electricity.
How do I Compare Efficiencies??
All new heat pumps are rated as to efficiency. The SEER (Seasonal Energy Efficiency Rating) is the efficiency rating for a particular model and is a rating of its efficiency while it is in its air conditioning mode. The HSPF (Heating Seasonal Performance Factor) is the efficiency rating of the heat pump when it's in the heating mode.
What do SEER and HSPF really mean? If you buy a heat pump with a SEER of 14.5 and HSPF of 7.5, it means you will get 14.5 BTUH (a measurement of heat energy) of cooling for every watt-hour of electric energy and 7.5 BTUH of heating for every watt-hour of electric energy. Since you buy electricity by kWh (1000 watt-hours) you can say that you get 14,500 BTUH of cooling per kWh and 7,500 BTUH of heating per kWh.
Newer heat pumps and air conditioners are more than twice as efficient as older models. So when you replace an old heat pump with a new one, your savings go on all year.
Capacity: How big a system is needed?
A common mistake made in choosing any heating and cooling system is installing a system that is too big. Partly to blame for this is the old slogan, "If a little will do a little good, a lot will do a lot of good." Also, partly to blame are installers who are not sure what size is needed, so they oversize to make sure.
When a unit is improperly sized, the first thing lost is comfort. When an air conditioner is running, it is removing moisture from the air, dropping the humidity level and making the air more comfortable. Therefore, you would receive the highest level of comfort if the unit would run all the time. However, the house would get too cold. An oversized unit will cool the house too fast and then kick off, before it has time to remove very much humidity.
A similar situation can occur in winter. Gas furnaces which are oversized heat the air up in winter too fast, then kick off. The room cools down quickly and the unit kicks on again, taking our bodies through periods of warm and cool, warm and cool.
Heat pump comfort
There is a distinct difference in the heat produced by a heat pump compared to air from a furnace. The normal temperature of air from a heat pump in winter is about 90 degrees. A gas furnace blows air at about 130 degrees.
The furnace air is noticeably hotter and dryer, but the heat pump's air is a more even heat.
Why do some people complain about heat pumps? Proper installation is more critical with a heat pump than with a gas furnace. A gas furnace producing 130 degree air can sometimes overcome energy loss caused by ductwork leaks or drafty, poorly insulated houses. A heat pump system which is not properly installed and properly set up will not perform as it should. Many times the heat pump itself is blamed, when in actuality the installation was not done properly, or the heat pump is not the best choice for the application. If there are problems with the installation, they usually surface when the weather is coldest.
The choice is yours
Now you should know enough about heat pumps to make an informed decision. Compare the numbers on heating cost in the accompanying chart. Then consider cost of the system, cost of operation and comfort.