The first rule of thumb in estimating the HVAC unit system size you need  to remember that there is no simplified one-size-fits-all square footage answer. The result of using a standard formula based solely on square footage is that you tend to end up with a system that’s too large for your space. That means you’re paying more to purchase and install the larger unit. While it may seem counter-intuitive, a larger unit fails to accurately maintain the temperature at which you’d like your home set. Consequently, you pay more in energy bills.


If you have an older home or office, it may not have adequate ventilation or ductwork to accommodate the needs of a new system. An HVAC retrofit might be necessary in order to get the maximum efficiency out of your unit.

Another consideration with older homes is the condition of the electrical system. It needs to be up to code to be able to handle your new system.


The number and condition of windows definitely have an effect on the size of unit you select. However, that’s only part of the window information you need. Where they’re placed in your home is also a contributing factor. If your windows receive a great deal of sunshine throughout the day, that means more heat enters your home. The cooling system will have to work harder during our Las Vegas summers to maintain a comfortable temperature, but the furnace produces less energy during the winter.

Window type also factors into the energy your HVAC expends. Single pane windows aren’t as efficient at insulating as are double or triple paned windows. While we’re on the topic, window treatments also figure into the calculations.

HVAC Units: a Guide to Types and Sizes - AC Masters


When your HVAC is insufficient to manage the space, you’ll notice that it doesn’t seem to run consistently. It will either go nonstop or operate in short bursts throughout the day.

You will also notice more moisture in your space because the unit isn’t powerful enough to adequately maintain the temperature and remove moisture. Added moisture can ultimately lead to mold growth, which contributes to an unhealthy environment.

As mentioned above, oversized HVAC systems also create problems in your space. It may seem like a larger unit will work even better, but the opposite is true. One of the problems is that a system that’s too large doesn’t run long enough to condense the air that accumulates on the coils, so it doesn’t dehumidify the air effectively. Here again, you end up with more moisture.

You may also hear a noisy unit because it’s not running efficiently. Not only are you faced with an uncomfortable physical environment and nuisance noise levels, but you also end up paying much higher energy bills because of all the extra effort your unit has to exert.


All air leaks should be addressed and remedied in order to get the maximum efficiency out of an HVAC unit. That includes adding weather-stripping around windows and doors to effectively seal them.


The amount and type of insulation you have in your home is a major factor in maintaining a consistent and comfortable temperature. Your home’s R-value should also be included in the load calculations.  If additional insulation is required, that can be added when the ductwork is installed.



Comments are disabled.