Monday, February 16, 2015

How does a heat pump work?

If you have a Heat Pump, you may not know all you should know to make it as efficient as possible. To get the full benefits of the Heat Pump, here are some tips.

The heat pump is a very efficient piece of equipment - today’s units are over 300% efficient as compared to a very good gas heater at 95%.  It can do this because it does not burn fuel to CREATE heat - it uses much less fuel to MOVE heat.  It pumps it from outside in during the winter and from inside out during the summer.
Your Heat Pump, like any furnace, circulates and reheats room air.  Most furnaces raise the temperature of the air passing through by about 50°, giving you a 120° supply temperature with your thermostat at 70° (70°+50°=120°).  A heat pump, on the other hand, is designed to give a lower 25° boost to the air passing through, thus delivering a 95° supply (70°+25°=95°).  This lower supply temperature is high enough to heat the house, but is close to body temperature and can, at times, feel cool if you are sitting or standing in the air flow.  You can see that raising or lowering the thermostat setting also raises and lowers the supply temperature, so we suggest keeping your thermostat at 69-70° for starters so that the supply temperature is high enough to keep you comfortable.

Because the supply air temperature is lower than that of a gas or oil furnace, the Heat Pump may run longer to deliver the same amount of heat.  When it gets close to 30° outside, the Heat Pump will run almost continuously.  Remember that it is designed to do so.

You actually have two furnaces - the Heat Pump, and the back up coils that look and act just like your toaster or oven coils.  The Heat Pump is very efficient and inexpensive to run but the backup is not as efficient and is more expensive to run.  As the outside temperature drops to about 30°, the heat pump starts to need help from the backup.  Your thermostat will automatically add back up heat as needed, and that proportion increases from no back up at 30° to all back up at close to 0°.  Remember that this happens without any help on your part.  

Raising and lowering a heat pump thermostat will actually raise your bill because it forces the more expensive back up to come on when it would not normally be needed.  So be sure to set your thermostat on a comfortable temperature and not move it.

The "emergency" switch on your thermostat is for "emergencies".  It is designed to give you heat even if the Heat Pump is damaged or out of commission.  When the switch is flipped, your efficient Heat Pump is shut off and the house heats only with the not-so-efficient back up.  This will raise your heating costs, so remember only to use the "emergency" switch if your Heat Pump has a real emergency.

Your outside unit will occasionally have a frost or ice buildup.  This is normal and temporary.  If the ice or frost persists for more than an hour, call your contractor for service.

Your filter is designed to keep airborne dirt from clogging your heating coils inside the heat pump.  If the filter itself gets clogged, then the heat pump (or any furnace) can't move enough air, and it won't heat your house properly.  Check the filter every two weeks when the house is new, and then less frequently as you see it is not so dirty.  Eventually check it three times a season - both heating and cooling season.
A Heat Pump is about the least expensive way to heat your house, so consider one of these “modern marvels”. 
Advanced Heating and Air
Randall Combs
Office: (865) 933-5538