DIY Network

Keeping It Cool: How Big Should Your AC Unit Be? From "Blueprint for Home Building" episode DBHB-108

Size does matter when it comes to choosing an air conditioning unit for your home, but larger may not always be better as you'll find out in this segment.

In this segment host Jeff Wilson talks about another important part of purchasing a cooling system for your new home -- the size.

"A lot of people have the perception that a bigger unit is better for the heating and cooling system in their house," Eric Newhouse, systems integration designer at IBACOS, said. "And that's really not the case. A properly sized piece of equipment that's not too large is going to work much more efficiently in maintaining better and more even comfort in your home."

Alert: Don't get oversold about systems that are much more expensive than they need to be simply due to their size.

"Sizing" means to literally find the right size or cooling capacity of the air conditioning system for your home. Unfortunately, many homes have systems that are too big or too small for them. This can lead to a loss of cooling efficiency and high electricity bills.

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Figure A

Components of Air Condition Size

There are several components that impact what proper sizing would be for the air conditioning unit in your home:

• Geography.

• Heating and Cooling Hours.

• Orientation of the House.

• Windows in the House.

There are compressor and other component failures that have nothing to do with the equipment, but with improper sizing or installation of the air conditioning unit.

"If you oversize the cooling system in your house, what will happen is that it will only operate in short little bursts," Newhouse said. "And since it's operating for a short period of time, it doesn't have the opportunity to dehumidify the air in your home."

If you properly size the cooling system (figure A), it's going to run a little bit longer every time it turns on, and during this longer period of running, it will provide cooling -- and it will dehumidify and provide better comfort in your home. So the bottom line is, bigger is "not" always better.

Even the orientation of your house can have a big effect on sizing your cooling system. The way the windows are laid out, for example. Do they face north or south? This will certainly increase either the heating or cooling load.

Because sizing is so important in your home's air conditioning, how that size is determined is crucial.

Construction Advice: When sizing a cooling system for your home, keep in mind that it's better to undersize than to oversize. A smaller system may run a bit more often, but it will cost less to operate. A larger system will cost more to operate, in addition to being inefficient, which will cost more money in the long run.

In the next episode our host will look at the best way to determine the size for your HVAC system.

GUESTS :

Eric Newhouse
Systems Integration Designer
IBACOS
Website: www.ibacos.com

Dave Meyers
Vice President, National Accounts
Carrier Corp.,br> 7310 W. Morris St.
Indianapolis, IN 46220
E-mail: david.Meyers@carrier.litc.com

Bob Balzar
Director
Nevada Power Co.
6226 W. Sahara
E-mail: bbalzar@nevp.com

Richard Waite
Vice President
Sierra Air and Silverado Mechanical
816 Roaring Falls Ave.
Henderson, NV 89052
E-mail: rwaite@lvcm.com

Paul Raymer
President
Tamarack Technologies
PO Box 490
W. Wareham, MA 02576
E-mail: praymer@tamtech.com