Options For Dealing With An Oversized Gas Furnace

18 July 2015
 Categories: Construction & Contractors, Blog


Getting the right size furnace for a home can be very challenging, and many homeowners end up with something that's too big for their needs. In addition to wasting energy, an oversized furnace may wear out faster, costing you more money in repairs or forcing you to replace it sooner than expected. Here's how to determine if your furnace is too big for your home and a couple of ways you can deal with the problem.

Symptoms of an Oversized Furnace

Signs your furnace may be too big for your home:

  • Short cycling – The heating cycle is the time it takes for the furnace to heat your home. An oversized furnace will heat the home faster, resulting in shorter cycling times. The problem is the heater may not run long enough to allow the humidity in your home to reach an appropriate level. It may also result in an uneven distribution of heat with some parts of your house getting hot and others staying cold. Your furnace will also turn on and off more often, causing the parts to wear out quicker. A furnace should cycle on about every 10 to 20 minutes. Anything significantly more than that denotes a problem.
  • Higher energy bills – Furnaces use the most energy when starting up and shutting down, so one that turns on and off more frequently because of short cycling will increase your energy bills.
  • Wild temperature swings – The temperature in your home will quickly change from cold to hot and back again because the furnace is not staying on long enough. For instance, you'll feel warm for the five minutes the furnace is on but then feel cold when the furnace shuts off and the house rapidly cools. When a furnace is adequately sized for the home, it runs longer, letting you feel comfortable for longer periods of time.
  • Sudden or frequent repairs – The furnace needs to be repaired sooner or more frequently than expected. Having to replace or repair the same parts in a relatively short period of time can also indicate the furnace is oversized.

You can also determine if your furnace is oversized by calculating the amount of BTUs that your home needs and comparing it to the amount your furnace puts out. In general, your furnace only needs to put out 25 to 30 BTUs per square feet (e.g. 25,000 to 30,000 for a 1,000 square-foot home). However, this can vary depending on your location.

Two Options for Dealing with an Oversized Furnace

The best option for dealing with an oversized furnace is to completely replace it with something that's more efficient. This can save you money and headaches over the long term. However, it costs an average of $3,867 to replace a furnace. You may want to pursue this option if your existing furnace is nearing the end of its life cycle or you're already investing in renovation. You can always sell your old one to recoup some of the money you spend on a new machine.

If replacing the appliance is not financially viable, then derating your existing furnace may help. This procedure involves either lowering the amount of gas the furnace uses or reducing the size of the pipes distributing the gas. This, in turn, will reduce the amount of heat the appliance produces and minimize some of the problems associated with having an oversized furnace.

However, derating a furnace can also cause problems. The lower temperature could cause pressure switches to malfunction, soot to form, or increase your risk of carbon monoxide poisoning. Additionally, not all cities allow homeowners to derate their furnaces, so you'll need to check your local building codes first.

For more ideas on dealing with an oversized furnace, connect with a heating repair company in your area. For more information, contact a business like Plumb Pros Plumbing Heating & Drains.