Why Does My Heater Keep Turning On And Off?

Your heater may be turning on and off – or short cycling for three basic reasons. The thermostat may have failed, your air filter may be clogged, or your furnace may be too large for your home.

The good news is that not all of these require furnace repair.

Let’s explore these three reasons in a little more depth.

Three Reasons Your Heater Short-Cycles.

Short-cycling is when your furnace turns on and off in close set intervals. Short-cycling puts extra strain on the furnace and may even lead to expensive repairs and possibly shorten the life of your unit.

Plus, the constant on and off will increase your energy bills as your system has to work overtime to achieve the desired setting.

Let’s break down the 3 most likely causes.

Faulty Thermostat

The thermostat is the part of the system that calls for either heating or cooling. If the thermostat is faulty or the wiring has gone bad, the thermostat may be misreading the need for heat and “over-call” for heat or cooling.

Another factor to look for is the location of the thermostat. Is the thermostat located in a drafty area or neat direct sunlight?

If so, an open door or window or a direct stream of sunlight may “fool” the thermostat into calling for heating or cooling because of a momentary environmental change.

Dirty Air Filter

We can’t talk about air filter maintenance enough. The recommended monthly replacement can help to extend the life of your HVAC system and provide reliable comfort.

Your furnace needs proper air circulation to run smoothly and efficiently. The heat exchanger needs blowing over it or it will overheat – causing the furnace to shut down. When the heat exchanger cools down, it reactivates trying to achieve the desired temperature – thus causing the short cycling.

Oversized Furnace

Believe it or not there is such a thing as too much of a good thing. A furnace needs to be sized properly for not only the size of the home or office but also for the layout and configuration.

A furnace that is too big for your home heats the home quickly. When the home cools down the furnace is called on to heat again, causing what seems like a never ending loop of on and off.

This is by far the most expensive repair to make to eliminate short-cycling. Only a qualified HVAC technician to truly size your unit properly for your living space and needs.

Troubleshooting Your Problem

When troubleshooting any kind of problem, it is best to go for the low hanging fruit. If you feel that your furnace is operating more than it should be, check your air filter first.

This simple fix can save you many dollars on an expensive service call. Plus air filters can be purchased at most hardware and box stores.

But if you find that your problem is not a clogged filter, don’t hesitate to contact your qualified HVAC technician.

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