Start and Stop of HVAC

DATE: August 23, 2016

When you talk to car ‘experts’ they will tell you one of the worst things you can do to a car’s engine is…start it. That’s right. When the engine is cold and the oil hasn’t circulated, you have all those internal parts moving against one another in addition to the initial ‘start up’ that requires more effort than to have it on and running.

The same can be said for your air conditioning or heating system. When your thermostat calls for air conditioning, the unit starts up from a dead stop. There are moving parts that have to be lubricated (not unlike your car engine) and there is more energy required to start up the system than to have it on and running. If you want a vivid illustration, simply have someone watch your electric meter when the unit first starts up. You’ll see a distinctive increase in the speed of the meter and then once the unit is running, it settles into a slower pace.

Simply put, its more stressful on the equipment initially and over time, as well as more expensive to have a system starting and stopping. Remember, there are no benefits to having a system operating in this manner. Think of it this way. What is the benefit of investing in a high-efficiency system if the sizing of it will not enable you to achieve its highest efficiency? None that I can think of.

The heating side of your system is the same, although it may not be as obvious as with the air conditioning. If the heating system is oversized, you will still experience the short-cycling which results in a loss of comfort, increased wear and tear on the equipment, but may not reflect as much of an increase in operating costs (although there would certainly be some). So what all is taken into consideration when sizing your HVAC system? Follow next week’s blog to find out!

John L. Lloyd

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