HVAC FAQs - Gas Furnaces and Boilers

All manufacturers recommend annual maintenance by a trained service technician. On a gas furnace, this helps ensure safe and efficient operation. If you have an oil furnace, yearly tune-ups are a necessity due to the dirty fuel and a more sensitive burn cycle. A modern oil furnace that is not maintained can drop efficiency from 80% to 50-60% in just two years. Clogged fuel filters can lead to fuel pump failure. A dirty burner can cause soot buildup in the heat exchanger and chimney, requiring an expensive chimney cleaning. An annual tune-up can keep your furnace at peak efficiency and help avoid these costly problems.

Yes. Most furnaces are shipped for use with natural gas and are field-converted to propane by the installers. The natural gas components are typically left near the furnace in case natural gas becomes available in the future. If the required parts are missing, they can be ordered. The cost for conversion is generally $200-$300.

Carbon monoxide is an odorless poison gas produced in small amounts by any gas or propane appliance. CO (Carbon monOxide) produced by a furnace is removed from the house by the chimney. CO from a gas cook stove is normally produced in small quantities and should not cause a safety issue. CO becomes a problem when an appliance malfunctions. A bird could get stuck in a chimney and within minutes a furnace or water heater could fill a house with CO. Any house with gas or propane appliances should have a CO detector. We have personally seen cases were a furnace malfunctioned and the CO detector woke the family and saved lives. Carbon monoxide detectors are inexpensive and can be purchased at any home store.

The method for re-lighting a pilot varies from one furnace to another and instructions should be printed on the furnace door. Occasionally a pilot light can be blown out by a strong down draft. However, a blown pilot is usually caused by a dirty pilot burner or a bad thermocouple. For safety reasons, these furnace repairs should be completed by a technician. Modern furnaces do not have standing pilots, and attempting to manually light a furnace can be very dangerous. Newer furnaces have either an automatic spark to relight the pilot, or an electronic ignition system (hot surface ignitor), and cannot be manually lit.

Filter change frequency for you furnace depends 4 factors: furnace size, filter type, filter size, and the dust conditions in your particular home. There’s not enough room to properly address this topic here, so we devoted an entire page to When to change your furnace filter.