Guide to Heat Pumps

Heat is all around us, in air, water and soil. A heat pump transfers this heat, using a refrigeration cycle, from one place to another much like your refrigerator works. In the winter the pump warms the house by moving heat to the inside and in the summer it cools by moving the heat outdoors. Heat pumps usually have a “backup” heating system to assist the pump when the outside air is below 24-28 degrees F.

Types of Heat Pumps

• Single package – Smaller and easier to install for one or two room applications.
• Split package – Consists of two cabinet-sized units: one inside the house and the other outside. Small pipes connect the two units through the wall. This has a larger capacity, serving more space. This is the most common, and usually uses ductwork.

Advantages

• Energy savings
• More comfortable, constant indoor temperature
• Clean and safe to operate

Disadvantages

• Initial cost is higher
• Can be noisy, so placement is important
• Sizing

Proper sizing is important. If the unit is too big, you not only pay for increased capacity, but it will also go on and off frequently. This is both uncomfortable and causes unnecessary wear on the compressor.

If it is too small, it will more often rely on its electrical resistance backup heat strips. The steadier the heat pump works, without using its backup, the better.

Ratings

COP – Coefficiency of Performance compares heat output with energy input. “2” means there is twice as much energy being delivered as there is energy being used by the pump only. The higher the number, the better.

HSPF – Heating Season Performance Factor is the average energy input for heat output over a heating season, this time including defrosting, backup heat, fans, etc. The higher the number, the better.

Ductwork

The efficiency of the heat pump depends heavily on the efficiency of its ductwork. This means they should be well sealed and insulated to at least R-8. Runs should be as short and straight as possible, with rounded turns.