Why do I need a bigger furnace to have a 5 ton AC?

Question

The model of furnace already installed in my house according to an ac contractor after checking the model is good for 1500 sq ft. My house is 2300 sq ft. and need a 5 ton ac per the contractor (4 ton min) to cool. He said i will need a bigger furnace, because my current furnace can only handle a 3 ton ac which is not big enough for my house. Can anyone tell me why I would need a bigger furnace? Can I install a 5 ton ac with my current furnace?

I leave South Bay San Diego.

Answer 1

I had the same problem too. My old A/C unit was only 2 ton for a 3,200 sq. ft. 2 story house. The old A/C would run all day long and never shut off, also, it would not feel very cool for having A/C. The A/C contractor said that the  5 ton unit would be more energy efficient- which it is by looking at my recent bills- and it would also not have to work as hard to cool the house. I don't regret getting new A/C and furnace 2 yrs. ago- best thing I could have done. I feel warmth in the winter and cool in the summer. The furnace though, has to be the same size as the A/C unit so it will work well for you.

Answer 2

You don't need a contractor to tell you your AC is big enough.

You will feel it this summer.  On the hottest days, if the AC shutts off  from time to time with the temp outside in the 90's and the AC setting at 78; your AC is big enough.  If the temp outside is 90's and the inside temp is 80 or above and the AC doesn't shut off until well after dark, you need a bigger AC.  Well insulated houses with double pane windows need less AC per sq ft than older homes.  Some contractors need more work/money.  South Bay San Diego: you may be just fine. El Cajon/Santee/Bakersfield/Sacramento: more AC needed.

Answer 3

HVAC Tech.: Unless you have "three phase" electric you are not going to install a "single" unit. You will need two units to deliver the cooling you need. 2 ton up-stairs, 3 or 3 1/2 ton down-stairs. As you live in Southern Calif. you don't get cold enough in winter (?) for a larger heater. Your current heater Willl be able to handle the larger unit . While the smaller one Will take care of the upstairs. the smaller wil help the other one handle summer loads, and save you money by shutting down when not needing.

Answer 4

Was a Manual J load calculation performed to prove you need a 5 ton systems. Every area is different. My house is 2300 square feet and only has a 2.5 ton air conditioner. A Manual J load calc was performed and it works great.

If you post the model number of your furnace, I could tell you what size a/c (nominal tonnage) that it could handle.

Answer 5

air handler/blower motor is the main reason. sizing hvac equipment requires a load calculation on the structure. i am in no way saying your guy is wrong, BUT, if he didnt present you with a written load calc, and about a 300.00 bill, i would consider another opinion.

whatever the case may be, the inside air handler and blower has to match the outside unit for efficiency! youre fixing to spend big bux and should  make certain you get the very best efficiency for your money. i would suggest a load calculation! (five ton sounds way oversized to me and if you have a two story or a loft, you should consider zone heat/cooling.) good grief, i live in texas and have a 3 ton unit, 2k sq ft. no heat pump. e- heat.

remember, the indoor coil has to match the outside coil and then you need the correct airflow across the propperly sized coil. i also assume you are getting a heat pump furnace, correct?

Answer 6

if your a size 5 and then you gain 100 lbs are you still going to fit into your old clothes? same thing with air. first of all your furnace isn't big enough for your size house. i bet your gas bills are just atrocious trying to heat the house in the winter. well it cant do the job with air conditioning either. all it will do is cause the air conditioning unit to run 24-7 and make your electric rates hit the roof. also it could cause the unit to freeze up making it not run at all.