A furnace that turns on and off rapidly, otherwise known as short cycling, can present an urgent problem when you’re trying to stay warm this winter in Harrisonburg, VA. Thankfully, we can resolve this problem, and the first step to solving it is to understand why it happens. Here are a few reasons why your furnace might start short cycling.


When furnaces start creeping up toward the end of their lifespans, all sorts of problems begin emerging with growing frequency. If you have a gas-powered furnace, it becomes especially likely to lapse into short cycling. The corresponding figure for an electrically powered furnace is about 20-30 years.

Once your unit has aged this much, repairing it will likely not resolve the short cycling problem for long. Rather than dealing with constant repair calls, it might make more sense to install a new furnace. Our technicians can help you determine if a repair or replacement is the best solution.


Your furnace may overheat for a variety of reasons, and the usual response to this issue is for the unit to shut down. If overheating happens repeatedly, it may manifest as short cycling.

Your furnace may overheat if its flame-sensing equipment is faulty and corroded. It may also happen if the unit’s air filters or valves are full of soot and other debris, thus inhibiting airflow and causing the warm air to increase the temperature of the unit’s interior. Our HVAC technicians can carefully inspect your furnace, determine the exact cause of the problem and fix it by repairing or cleaning the relevant parts.

Clogged Flue Pipe

The purpose of a furnace’s flue pipe is to expel the exhaust fumes that the combustion process generates. If any obstruction forms in this pipe, your home may fill with carbon monoxide and other toxic gases. Therefore, as a safety measure, your furnace may automatically shut down in response.

Short cycling is a grave problem that can ruin your furnace if you don’t address it. Call Valley Air Heating, Cooling & Plumbing and get the best heating repair services around Harrisonburg, VA.

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