Why You Need to Understand Load Calculation

The hot temperatures are coming to an end and the nights are getting chillier so you decided to turn on the heat one night to take the chill off. To your surprise, your heat doesn’t work and is only blowing out cold air. The next day, you give us a call at Dave’s Cooling and Heating and we come out to take a look at your system. Unfortunately, your home and HVAC unit are older and your system is beyond repair so we suggest getting a new one. 

A good HVAC installer will know that regardless of what size unit was in there, they need to do a load calculation. You have probably heard of the term load calculation but may not know exactly what it means or how important it is to you. We, at Dave’s Cooling and Heating, know exactly how important it is and will always do one on new installations whether they are for new construction or not. 

What is load calculation?

Load calculation is simply determining the needed furnace and/or air conditioner size for a home. 

A few decades ago, when central heat and air were just becoming the norm in homes, HVAC companies would calculate the square footage of a house and solely use that information to determine the needed size for their unit. As a result, units were often much bigger than required because the home’s heat gain and loss were not taken into consideration. 

Then, over forty years ago, the Air Conditioning Contractors of America was formed which developed a specific way to determine the load calculation which involves the CLF/CLTD method. This method takes into consideration things like appliances that generate heat, the windows, insulation and much more. All of which play an important part in how a home is able to hold heat. 

Why is load calculation so important?

Load calculation is so important because having the right-sized unit can help you avoid some problems with running oversized equipment. 


When you have an oversized unit, you will pay more for the unit itself and to run the unit. Equipment that has higher capacity costs more so by getting a unit that is the right size, you will be charged the right price. Also, when a unit is too big, it short cycles which is not efficient and will increase your electric bill. 


Speaking of short cycling, when this happens it causes the temperature to fluctuate more rapidly. No one likes a room that doesn’t maintain a comfortable temperature for a period of time. 

Equipment longevity

Short cycling will also cause your system to wear out faster. Imagine if you kept turning off your car every mile and then turned it back on. That would really put some wear and tear on your engine and the car wouldn’t last long. The same will happen when the HVAC unit is shutting on and off. 

If you’re in the Frederick County area and considering a new unit, please consider using an HVAC company that understands the importance of load calculation. We’d be happy to give you a free estimate so give us a call at 301.401.2780.

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