How to put a single, powerful air conditioning unit to work cooling your entire home
by Tom Mercer
High BTU Air Conditioners
If you're shopping for air conditioners, you may have noticed air conditioning units in the 20,000 BTU, 24,000 BTU, or 25,000 BTU range, all the way up to 27,000 BTU and 34,000 BTU, and wondered if you could use that to cool 3 bedrooms, 2 bedrooms and a kitchen, or even your whole house.
Although central air might be cooler, it's several times more expensive.
Preparing your system
To cool your whole house with a single air conditioner, use your furnace fan. Put the unit in a room with a return duct, or install the air conditioner as close as possible to a return vent. Try to place the unit where the impact from noise will be minimized. Usually furnace fans are located in basements or out-of-the-way parts of homes, but find the best location for your system.
Close the supply vent in the room where you install the air conditioner, and leave the return vent open. Close all the other return vents in the system.
Finding the right air conditioner
First, you're going to need to calculate the BTU requirements for your home. Use this air conditioning BTU calculator to find out how many BTU you need per room type and square footage.
You may have heard that going the next size up is a good thing, but there is a drawback. Going more than 1.5 or 2.0 times the actual BTU requirement will cause your unit to cycle on and off, whereas proper sizing keeps air dehumidified, and saves money on energy bills by running more efficiently.
Think: slow-and-steady = efficiency.
Tips for maximum efficiency
Close supply vents in all the rooms except those you are occupying.
Running the fan at the highest speeds can boost efficiency, but will be noisier.
Don't use an exhaust fan to 'push' hot air out. This will pull hot air through cracks and leak cool air.
Final Thoughts
Using a high BTU Air Conditioner to pump cool air through your existing ventilation system can save you $400 - $2,500 upfront, save $100s on monthly electricity bills, and keep you cool in the summer months.