When the heating season begins, many people notice that it looks like their HVAC unit is smoking. Obviously, that seems like a cause for concern! No heating units should ever be visibly smoking — even today's fuels don't produce visible smoke.
Fortunately, this is usually a harmless phenomenon caused by steam. We're going to go over three questions that you need to ask to figure out what's really going on with your unit.
Is The Unit Outside?
When you notice this "smoke" effect, are you looking at the outdoor unit? If so, the chances are good that it's nothing to worry about (we'll talk about why in just a bit). However, indoor units, including units in basements or garages, shouldn't be smoking at all. If you notice or smell smoke around an indoor heating unit, shut it off immediately and arrange for an inspection as quickly as you can to see what the problem is. Part of the furnace may be compromised, or a fan motor may have burnt out.
Do You Have a Heat Pump?
If your outdoor unit looks like it's smoking, do you have a heat pump? Heat pumps work a lot like air conditioners, except they can also reverse and draw heat from outside air and pump it indoors to help heat a home. This is incredibly efficient — in fact, today's heat pumps are so good that they can even pull heat out of the air when temperatures start dropping toward freezing (although not as efficiently).
However, this creates a problem. Frost can build up on the coils of the outdoor unit due to gathered condensation, inhibiting the ability to pull heat from the air. A heat pump solves this problem by going into defrost mode. In defrost mode, the heat pump fan shuts down and it reverses, pulling hot air outside. This switches where the heated refrigerant travels, and heats up the frosted-over coils, melting the frost. This, of course, creates steam, which many new homeowners first mistake as smoke. Don't worry! It's not smoke. Your unit is simply recovering from some hard work. Remember, you can also try smelling it to see if it's smoke or steam!
How Long Does It Last?
Finally, ask how long steam comes off your unit. For the average household heat pump, the defrost cycle should only last for several minutes, and should only happen once every few hours on average (assuming cold conditions). If your defrost cycle seems to come on a lot and doesn't seem to stop for a long time, that's a sign something is wrong with the defrost mode. Call a professional to inspect the defrost controls, sensors, outdoor fan, and other problems that may be keeping defrost from acting correctly. You may need to replace a part, or give your outdoor unit a thorough cleaning to fix the problem!
Have any questions, or want to know more about something that's worrying you about your heating or cooling units? Give us a call!