Tip & How-To about Heating & Cooling
How on earth can you get hot air or hot water from very cold outside air? How does a heat pump make this heat out of cold air?
When certain gases change their state from a liquid to a gas or from a gas to a liquid the magic happens.
A heat pump can do some pretty amazing things, when it comes to making heat. To understand the way they work, you must first understand what happens when certain gases change from a liquid state to a gas and back to a liquid again. To simplify it a bit we need to look at a basic air conditioning system. The refrigerant in an air conditioning system is changing to a liquid in the outdoor condenser. The compressor compresses the gas forming a hot gas. As this gas cools under high pressure it changes into a liquid form.
Inside the indoor coil the liquid is pushed through a small hole or orifice. When it comes out the other side it rapidly changes it’s state to a gas as the pressure suddenly drops. The rapid pressure drop changes the refrigerant to a very cold gas. Air flowing over the cold gas inside the pipes makes the air cool and provides air conditioning.
Now for a heat pump the process is much the same, only coils are just switched by used a reversing valve in the outdoor condenser unit. Instead of the heat being purged to the outside from the condenser unit, the indoor unit then becomes the condenser coil. The outdoor coil becomes the cold coil and cools the outside. This is why if it is very cold outside the unit will have to run in air conditioning mode for a short time to defrost the outside cold coil. When this happens the system will usually have electric heat inside to run and keep the indoor air warm.
The reality is that a heat pump is really no more than an air conditioner running in reverse. Through the magic of using refrigerants, a heat pump can then run many times more efficiently than straight electric heat. A careful heat loss/gain should always be performed by a qualified service person before any sizing of a unit. Too large or too small of a heat pump system can make it inefficient and possibly cause it to be very uncomfortable. The longevity of the unit can also be affected by sizing and installation. Be patient and look carefully for the best contractor to install your system.
A properly designed and installed heat pump system can give you many years of comfort and efficiency. If you look for and find the contractor that can do the job right you will get many trouble free comfortable years from your heat pump unit.
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