With much of the country facing record-breaking cold temperatures, furnaces from coast to coast are working at capacity – and sometimes over-capacity. Regardless of the time of year, you always want to make sure that your furnace is working efficiently and properly.

One common issue for homeowners is a furnace that is short cycling – also known as overheating. When a furnace short cycles, it kicks off and on frequently with very little time in between.

What Causes a Furnace to Short-Cycle?

There are several things that can cause your heating system to short cycle. Some of these include:

  • A malfunctioning flame sensor or flame rod
  • Dirty furnace filters
  • Heat registers that are blocked
  • Exhaust vents that are blocked
  • A furnace that is too large for your home
  • A thermostat mounted in a bad location

While these issues aren’t the only possible causes of this type of malfunction, they are the most common. Let’s take a deeper look at the issues and find out what to look for.

Malfunctioning Flame Sensor or Rod

If your gas furnace flame shuts off almost immediately after lighting, you may have a bad flame sensor. To find out for sure, remove the cover from the furnace and look for the burner firing. You can also listen for the “whoosh” sound it makes. The inducer motor should run anywhere from 30-60 seconds before the gas fires. If the gas never fires, a sensor could be to blame.

This is because the sensor is designed to recognize when a gas valve has fired; if it doesn’t sense a flame, it will shut off the gas valve to prevent raw gas from flooding your home. Your sensor will need to be replaced – it’s a simple job that our HVAC experts in Napa can do.

A Dirty Furnace Filter

A dirty filter prevents a proper flow of return air into the furnace, which can cause your HVAC system to overheat. If your furnace gets too hot, the switch will shut it down to prevent damage. If you notice that your furnace shuts down after running only for a few minutes, the filter may be blocking that air flow. Fortunately, this is an easy fix, and it doesn’t require any specialty HVAC training: simply change your filter.

Blocked Heat Registers

Heat registers that are blocked don’t let enough air out of the HVAC system – one of the telltale signs that this may be your issue is if the air coming out of your open registers is hotter than normal. When registers are blocked, your furnace can’t disperse enough heat to function properly, causing it to overheat and shut down. Make sure your registers aren’t blocked and you don’t have too many dampers closed on your air ducts.

The Exhaust Vent is Blocked

This issue is one that is particularly dangerous because carbon monoxide could be allowed through the vent. Wild animals and birds building nests, snow, ice, and beehives can block the exhaust flue of your home. If you need help removing an animal, beehive, or other pest, you may want to call an animal control expert for help.

Your Furnace is Too Large

Bigger is not always better when it comes to furnaces. Unfortunately, it’s a common problem, though due to misinformed HVAC installers believing that bigger units will save the customer money. However, when a furnace is too large, it will deliver a large amount of warm air in a short amount of time, reaching the desired temperature quickly, then shut off. What a proper-sized furnace should do, however, is deliver warm air steadily – not in short bursts. Your furnace might be too large for your home, causing short cycling if you notice temperature swings, high heating bills, and frequent on/off cycles. Our experts in HVAC in Vallejo can help you choose the best (and properly sized) furnace for your home.

Your Thermostat is in a Bad Location

Yes, the location of your thermostat matters! If it’s getting warmed up before the rest of your house is, it will cause your furnace to shut off before it should. Your thermostat should never be installed right above a heating register or on the wall of a closet where a furnace is located, for example. With both of these locations, the thermostat will sense more heat quicker than the heat can reach the rest of your house. Simply relocate your thermostat to a central that is away from windows, registers, and furnace closet walls.

Should you need help with your furnace or any component of your HVAC system, contact our experts at A-1 Guaranteed today. We serve customers throughout Solano, Napa and Contra Costa counties, Vacaville, Fairfield, the Bay Area, and surrounding areas.