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Proper Sizing

When replacing a system either for heating or for cooling, a concern our customers commonly bring up is the sizing of the equipment. More often than not, most people ask for a unit that is at least as big as their current model or bigger than is necessary or required.

Sizing properly is one of the most important aspects of an installation and is never taken for granted on our end. Just because your current furnace or air conditioner is a certain size doesn’t make it right. I am talking about is oversizing or installing a larger system than is required.

On the heating side, in Cleveland, we size the furnace so it will maintain 72 degrees inside when the outside temperature drops to 0 degrees. At this point the furnace will be at a near constant run and will not shut off very often or at all. Now I know this makes most customers nervous to hear this but here are the facts.

All machines are most efficient when they are up and running and no longer cycling. Compare this to how your car gets the best milage on the highway. A machine is worn out by stopping and starting, there again, compare it to your car. Keep in mind, our average temperature in the middle of winter is around 30 degrees. We only see 0 temperature about 3% of the entire heating season.

Why would we want our furnace to shut off when it is 0 degrees outside? At these temperatures any cycling will create uncomfortable temperature swings inside that you can feel. Properly sized units become the most comfortable the colder it gets outside. And because they are sized right, fuel consumption will be very reasonable even though they are running a lot. It’s a fact.

On the air conditioning side, the same science applies. Here though, we size for 72 degrees inside when it is 95 outside. Air conditioners are required to keep our homes cool of course but 25% of their work is devoted to removal of humidity in our homes. If an air conditioner is oversized, the home will cool off too quickly and then stop. Also, if it is not running, it can’t remove humidity and in this case the home will feel like a cave, cool but damp. Not a very comfortable situation. Actually the removal of humidity is what makes you feel comfortable in the summer, not so much the drop in temperature.

There are many other reasons to properly size your equipment and these will be covered next month.