How Do I Know If My Furnace Is Sized Correctly For My House?

As long as you set the furnace and it maintains the heat and air conditioning/cooling AND it runs 10-15 minutes before turning off, odds are it’s sized correctly for your house. If your furnace is short-cycling (running only for 4-8 minutes then turning off, possibly with the fan still running) you are facing one of two problems; a dirty air filter or an incorrectly sized furnace. In general, for a 12-1400 square foot home, a 60-80,000 btu furnace would be required but it’s important to have a furnace installation technician that you trust to make sure you have the right specs when buying a new furnace. One of the worst things you can do, especially with newer high-efficiency furnaces, is to have too large of a furnace. High-efficiency furnaces are specifically designed to run longer and the wrong-sized furnace will end up short-cycling and causing you some possibly very expensive problems over the long term.

Your furnace short-cycling is a bad thing for a couple of reasons:

• A short cycle doesn’t give the furnace enough time to move the heat through the entire house. Your heat will be uneven and the peripheral parts of the home will never get fully heated.

• The reason why the furnace turns off so quickly is because of a safety feature built into the furnace called the “high limit switch”. The furnace’s heat exchanger is getting so hot that the high-limit switch is shutting the furnace off. Over time this can burn out the high limit switch and eventually cause the now unguarded heat exchanger to crack. This requires expensive repair and even replacement of your furnace.

If you aren’t sure whether or not you have the right-sized furnace for your home, call the friendly experts at Wilbur Henry. We would be happy to answer your questions and inspect your home’s furnace to make sure you and your family stay safe and comfortable this season.