What Are the Signs of an Incorrectly-Sized Furnace?

Having a correctly-sized furnace is critical to your indoor comfort during the cold months. While it may seem that “bigger is better” when it comes to home heating, it isn’t. The best way to avoid installing an improperly-sized heating system is to work with a trained professional. Since 1984, APC Plumbing & Heating has been installing heating systems in Denver, and our NATE-certified technicians can help you calculate the correct heating load for your home, and then install a heating system that fits.

Calculating Heating Load of Your Furnace

There are several factors that go into a heat load calculation:

  • Orientation of your home
  • Daytime heat gain
  • Level of insulation
  • How many windows and doors you have, and what type they are
  • Number of occupants of the home
  • Square footage
  • Floor plan
  • Temperature difference between indoors and outdoors (indoors is typically between 68-72 degrees)

How the air moves in your home, the number of people and how the sun affects the temperature of your home during the daytime are all important factors that have to be part of the calculation in order to truly ascertain how much heat you need. Simply calculating by square footage alone isn’t enough.

Problems with Furnace Sizing

So what happens if your heating system is too big or too small? Let’s take a look:

Too Small

When your heating system is too small, it can’t achieve the set temperature; this can be particularly troublesome at night, when the temperature drops. Unfortunately, your heating system will keep trying to reach the set temperature, so it keeps running – constantly. Constant operation isn’t good for the system because it can lead to accelerated wear and tear, overheating of components and possible breakdown of the system. In addition, your energy bills will go up and you’ll most likely be cold. It can be tempting to install a smaller furnace because it may cost less initially, but it can wind up costing you in the end.

Too Big

A system that is too big will heat your home so fast that it won’t be able to complete the full heating cycle. This can have several effects:

  • You’ll be uncomfortable – your home will heat up so quickly it may get too hot too soon, and then it will also cool down quickly, possibly making you cold again.
  • Your system will short-cycle – short-cycling occurs when your heating system is in a continuous cycle of turning on and off. This can cause with excessive wear-and-tear and prematurely age the components.
  • Your energy bills may go up – the constant on/off of short cycling uses more energy, especially at start-up, and the constant running requires more energy use.

When you work with a heating expert, he/she will perform a heat load calculation using the factors listed above to determine exactly how much heating your home really needs. This allows the technician to professionally install a heating system that is the right size for your home.

Call APC Plumbing & Heating and schedule an appointment with one of our installation experts.


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