Here’s a guide to what you can expect with your heat pump this winter.
1. During the cooling season, your heat pump operates like a conventional air conditioning system, i.e., the cool air blowing inside of your home. For example, if your home is 80°F inside, the air coming out of your registers should be around 60°F. In general, the air coming out is about 20° less than the air coming in. As the temperature cools down inside, the air coming out of the registers lowers. This is why it can take several hours to cool a home in the summertime when the air conditioning system has been turned off.
2. During the heating season, the heat pump rarely delivers very hot (135°F+) air as compared to a gas furnace, but instead delivers large quantities of warm (95-105°F) air. A heat pump will probably run almost continuously during cold weather. SPECIAL NOTE: During very cold weather the 95° air being delivered is warmer than the 68 to 75 degrees at which the thermostat is set.
3. A heat pump will “change tune” slightly as it moves from cooling to heating as the temperature varies, or as frost builds up on the outdoor coil.
4. Moisture will drain from the surface of the outdoor coil when the unit is in the heating cycle. This moisture will turn to frost when the outdoor temperature falls below 40°F.
5. The outdoor coil may become totally white with frost during cold weather. Unless this condition persists for more than 2 hours with defrosting, do not worry. Frost will build up very rapidly during cold, humid days.
6. When the heat pump defrosts, you will hear a slight “swoosh” as the outdoor fan motor turns off, and the air being delivered into your home will be slightly cooler than normal. The duration of a defrost cycle will vary from 1.5 to 10 minutes, depending upon the amount of frost on the outdoor coil.
7. Steam or fog from the outdoor coil is normal during defrost.
8. Newer, more efficient heat pumps tend to produce more defrost moisture than older equipment. This may be disconcerting with roof mounted equipment. The run-off from a defrost cycle is pure water, free of minerals, and has never been known to cause a problem.
9. It is extremely important that nothing restricts airflow or the defrost water runoff near the outdoor unit. Leaves, grass clippings, and the like should be cleaned off regularly. A word of caution: Due to the live electrical components in the system, this should only be done by a licensed contractor.
10. Return air filters must be cleaned or replaced as often as possible (1-3 months) unless you have a high efficiency filter which can last up to 1 year. Dirty air filters restrict airflow and increase operating costs.
11. Indoor air supply must not be blocked or restricted by furniture or drapery.
12. As the outdoor temperature drops, there is less heat in the outside air to be transferred into the home, and the heat load or heat requirement of the structure increases simultaneously. Electric auxiliary heat elements are staged on to compensate for the extra heat needed, especially in colder climates. More defrost cycles can be expected at the lowest operating temperatures especially if there is enough humidity in the outside air.