Will it be OK to install a 5 ton air conditioner, in a home that needs only a 3 ton ?

Question

Can I use a 60,000 BTU heater or should I use the matching 100,000 BTU of the air conditioner?

Answer 1

I would not use oversized equipment. They use more electricity and gas. A/C units especially work best when they are properly sized and run on longer cycles. An oversized A/C will cycle on and off too often and cause excessive wear.
The larger capacity furnace will use shorter "burn" times, cycling more often than the smaller furnace. You may get unpleasant swings in temperature in your home.

Answer 2

Why do you want to use a 5 ton unit??
Bigger is not always better, the Tim the Tool Man Taylor theory does not work here.

As several people have posted oversizing is bad in the way of air conditioning. I work in the field and the problem you have with oversizing is humidity control.

Some questions to ask are 1. are you going to be adding on to your home soon. 2. Did the current unit have trouble maintaining the comfort in the home. is this home located in a northern climate where your heating demand is higher than the cooling?

If your home did good properly tuned at 3 tons stay with the 3 ton, you can increase capacity up to 3.5 ton generally without problem but anything beyond this is not recommended.

Another thing to take into account here that no one mentioned it with the increase in capacity you also increase the static pressure in the duct causing wind noise and can actually blow apart the duct I have seen it happen. The duct work must be properly sized for the unit capacity.

Each ton of cooling requires 400cfm so from a 3 to 5 ton you are adding an additional 800 cfm to the system from 1200cfm to 2000cfm. Look at the variable speed and multi-stage condensing units. Check out Lennox's website.

I hope this helps.

ps correction on the BTU sited on the questions and answers. There are 12,000 btus per ton per hour this is how equipment is rated the condensor for 5 tons would be 60,000 btu's Gas furnaces unless they are the 90+ effiecency furnaces are at about 80% so for the 100,000 btu's of input gas heat you get about 80,000 btu's of heat out of it the other 20,000 btu's goes up the flue.

Answer 3

You got some correct answers. It will not dehumidify properly. While working in the Deep South (NOLA and the Gulf Coast) I have seen interior walls turn black and slick with slime due to poor dehumidification. You will not be comfortable. It will be a wet cool. It will feel clammy. If you do make the change to 5 tons without matching the heater cfm to the 5 ton evaporator, there will be days when the condensate produced by the evaporator will freeze and that is a whole other can of worms. You need to make a heat loss survey and match the furnace blower, evaporator, and condensing unit to the load in btu that the survey indicates is required.

Answer 4

I recommend NOT using a 5 Ton central air unit if your heat/cooling load only calls for a 3 Ton. the 5 Ton is over-sized and will 'short cycle' (come on & off frequently) and not dehumidfy the house. That will result in a rather uncomfortable house and most likely much higher electric bills.
A 60,000 btu furnace blower fan is to small to run a 5 Ton A/C.
If your going to install a new system, get it sized properly for your house. A good HVAC company should understand how to properly perform a heat/cooling analysis. the analysis will tell you the proper sized furnace and air conditioner. Do not just use square footage to make the size determination.

Answer 5

you should use close to the required size. Using a really over sized ac unit causes this problem; to really make the house comfortable you need to lower both the temperature and the humidity, an over sized unit will bring the temperature down and shut off before the humidity can be lowered.

Answer 6

NO. Use the correct size unit. The larger unit will not work as well. It will not run long enough to remove the humidity.

Answer 7

the standard is 1.25 btu's per square foot..400 square ft per ton....

Answer 8

You can use it; you just won't need to keep it on full blast.