I have a 1780 sq ft home, which unit would be more cost efficient a 4 ton or a 5 ton, please explain?
Question:i have an addition built on thats @ 270 sq ft, this is included in the 1780 sq ft of living space. this addition has no duct work or vents. What would be the difference in cooling of the home and how much more would i spend on my electrical bill if i went with a 4 ton unit? This is with the house well insulated, dual pane windows ect...
Answers:
what you need is for a hvac company to come and give you an estimate(usually always free). they will do a load calculation and this is figured by how many windows, doors, what direction the longest side of your house faces,how much insulation,etc.etc...usuall... though this normally equals out to about 500 sq ft per ton...so a four ton unit would do the best job...I would recommend you also put vents in the new addition..the biggest reasons for a four ton over a five ton is ... a 4 ton unit will run a little longer with less start ups than a 5 ton unit...less starting means less amps being pulled everytime unit starts...also four ton unit will use less electricity than a five ton unit will.. and will remove more humidity than a 5 ton will...will also save wear and tear of the parts and componets allowing them to last longer...
Based on 400 sq ft per ton your square ft will need 4 1/2 ton so I wouldn't advise the 4 ton as when its hot and you need it or having many guests over you'll be glad you have the 5 ton.
Rough formula says 1 per 500 sq ft which in your case whether you subtract the additional room (perhaps you use a window unit) or now or later decide to have duct work/vents added to your 'add-on' - you would still be good with the 4 ton as it would cover you up to 2000 sq ft.
"The most common sizing mistake is in over sizing. Contractors and customers usually think bigger is better but a larger air conditioner may not provide the best cooling. An oversized air conditioner penalizes you in the following ways:
* it costs more to buy.
* an oversized system will not run long enough to remove moisture from the house and can increase perceived humidity.
* the stress of short cycling (too many starts and stops) will shorten the life of the equipment and increase energy use.
* a larger air conditioner uses more electricity.
A system that is too small will not get the job done, especially in extreme weather conditions. The air conditioner will run constantly in the summer and the furnace will do the same in winter.
How big should your air conditioner be? The size of an air conditioner depends on several factors:
* how large your home is and how many windows it has;
* how much shade is on your home's windows, walls, and roof;
* how much insulation is in your home's ceiling and walls;
* how much air leaks into your home from the outside;
* how much heat the occupants and appliances in your home generate."
Check out the link I listed as source. Didn't want to bore anyone but there is a formula there that better figures proper size.
If you're having professionals do the job, they should know best. If you are 'doing yourself' I think you'd be safe with the 4. You may even see if any A/C places give free estimates (thinking they do). This way you could verify your info is correct.
Good Luck!!
HVAC contractors usually give a free estimate. While they are at your house they will do what is called a Manual J or load calculation. They will measure not only square footage but also your insulation and windows. These features help determine the correct size unit for your home.
Sounds like you are already being efficient with double pane windows and insulation. I would get a reputible company (check the BBB) to give me an estimate.
What is causing you to think either a 4 Ton or 5 Ton unit is properly sized for the house?
Have a good HVAC company perform a Heat/Cooling analysis for the house. Square footage alone is not the way to determine size. They need to take into consideration factors such as; direction the house faces, type & size of all windows and doors, type of insulation, in walls & attic, total perimeter of house, number of occupants etc. Properly done it will provide the necessary BTU's of Heat and Tonnage of cooling necessary.
Based on square footage a 4 or 5 Ton a/c unit is oversized and will not dehumidfy the house properly. It could also burn out in a few years.
Try to get at least 2 quotes and ask if they understand how to properly size the house as I described.
Total comfort in a house can often be determined by the properly sized equipment.
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