Signs of an Over/Undersized Furnace

If you have gone shopping for a furnace recently, you already know that the process is a lot more complicated than simply picking one in your price range. There’s all sorts of different factors to consider, from AFUE ratings to fuel and igniter types. One of the most important of these factors is the size of your furnace. Below, we’ll discuss the signs that your furnace is either too large or too small, as well as what that could mean for you.

Oversized Furnace

An oversized furnace tends to be more common than an undersized furnace on average. This is usually because of the mistaken belief that bigger is always better when it comes to a furnace. The biggest sign that you have an oversized furnace in your home is a phenomenon called “short-cycling.”

Short-cycling is what it’s called when your furnace continuously, rapidly turns on and off throughout the day. This is caused by the oversized furnace exceeding the safety measures designed for a much smaller system. When the furnace activates, the rapid rise in heat output causes your control system to think that the furnace is overheating. The system then shuts the furnace down as a safety measure to prevent fires. Once the furnace has cooled down a bit, it starts back up in an attempt to heat the house and the cycle starts all over again. This is an extremely inefficient process for heating, and can cost you a lot of money while simultaneously shortening the life of your furnace.

Undersized Furnace

An undersized furnace is less common than an oversized one, but still occurs often enough that you should be aware of the signs. The most common sign of an undersized furnace is that it is constantly on. Normally, when you turn on the heat the furnace will stay on long enough to reach the target temperature. It will then turn itself off until the thermostat detects an appreciable change in temperature, at which point the furnace will come back on to compensate for the heat loss. An undersized furnace can usually not make it to the desired temperature in the first place, leading to it always being on instead of cycling on and off.

If you have experienced any of these signs with your furnace, call Mediterranean Heating and Air Conditioning Inc. We provide heating maintenance services throughout Woodland Hills.