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Cowboys Air Conditioning & Heating Blog

Yes, Your Furnace Can Short Cycle


If you’ve ever dealt with an air conditioner short cycling, you may think it’s strictly an AC problem. But your furnace can short cycle, too. This can have similar causes to AC short cycling, and similar negative consequences as well. We’ll explain what short cycling is, how it can happen, what the risks are, and what to do if you notice your furnace doing it. 

What Short Cycling Is

Your furnace has a heating cycle. Depending on the type of furnace, this is a slightly different process, but the essentials are the same. The thermostat triggers the furnace to come on because the house’s temperature has gotten too low. The furnace starts up and begins warming your home. At a certain cut-off temperature, once your house is warm enough, the furnace shuts down again to wait until it gets the next signal from the thermostat. This cycle should only start up a handful of times per hour. If your furnace is short cycling, the heating cycle will be cut short, only to start again moments later, meaning that the furnace is starting up twice as often as it should or more.

Impacts of Furnace Short Cycling

If the heating cycle isn’t running to completion, your home comfort will be impacted. The house will just not get warm enough, and in particular, the heat won’t be well-distributed, leading to some parts of the house being much colder than others. But that’s the least of your worries. The startup is the most strenuous part of the cycle for your furnace. Doing that twice as often means twice as much wear and tear, twice as much strain on the system, and a much higher likelihood of repairs being required in the near future. All that stress even shortens the lifespan of the furnace. Getting prompt repair for furnace short cycling in San Antonio, TX can save you from waiting in the cold for your broken-down furnace to be repaired or replaced in the dead of winter.

Causes of Short Cycling

It may be that the limit switch is being triggered. In some cases, that’s because the limit switch is faulty, but it’s more likely that it’s accurately sensing overheating in the system. The most likely reason for this is that the air filter is clogged and not allowing enough cool air to pass into the system. It’s an easy fix, so check this first before calling for repairs! Simply remove and clean the filter and slide it back into place, and then wait and see if the problem stops.

It may be that the thermostat, not the furnace, is the true culprit. A miscalibration can cause the wrong signals to be sent, but a technician can recalibrate it and get things back on track.

If, instead of a furnace, you heat your home with a heat pump, check whether the indoor coils are encased in ice. This may indicate a refrigerant leak, and you’ll need a qualified heat pump repair technician. 

Finally, if the short cycling has been happening since your furnace was first installed, it may be incorrectly sized for your home. A too-large furnace intended to heat a larger home will bring the house to the desired temperature extremely quickly and end up cycling far too often. Again, because this leads to strain on the system, more repairs, and early replacement, you need to have it addressed.

Our professionals are ready to take care of you when you reach out. Contact Cowboys Air Conditioning & Heating today to schedule an appointment with our professionals.

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