Proper sizing of Central A/C System?
bill yahoo asked:
New warm air heat system being put in, so I’m adding central AC because the new ductwork will be going in anyway in the attic for the heat. I know all the so called “pros” are supposed to do some fancy calculations, but lets face it, in the real world, they don’t. So I was looking for some advanced knowledge so I can be armed when I talk to my installer. Can anyone give me any basic formula to go by? I think the smallest Central AC units are 1 1/2 Ton size, is that correct? So it would seem to make sense 1 1/2 Tons would be for about the smallest size house, around 700-800 square feet.
So, sorry if I repeat myself, but is there some basic freebie table where I can put in some figures and have it show the size needed so I can print it out?
Here is my situation: I’m in the northeast, Boston, Massachusetts area. Six room Ranch built on a slab/no basement, 1056 sq ft. Attic insulation R-30, ductwork insulated to R-6. Exterior walls R-6. Windows low-e glass argon gas-filled double pane. Any basic help out there? Thank ya’ much.
ethx: I should have put the words “fancy calculations” in quotation marks. I have read it is the right way to do it. What I meant was the “pros” I have spoken with, including the one doing my heat, brush it off as nothing to be bothered with, they “know” how to figure it.
So, I don’t think there is a basic answer to my basic question….is there a basic, easy formula for me to use to get a basic, rough idea of the size needed.
Leslie
New warm air heat system being put in, so I’m adding central AC because the new ductwork will be going in anyway in the attic for the heat. I know all the so called “pros” are supposed to do some fancy calculations, but lets face it, in the real world, they don’t. So I was looking for some advanced knowledge so I can be armed when I talk to my installer. Can anyone give me any basic formula to go by? I think the smallest Central AC units are 1 1/2 Ton size, is that correct? So it would seem to make sense 1 1/2 Tons would be for about the smallest size house, around 700-800 square feet.
So, sorry if I repeat myself, but is there some basic freebie table where I can put in some figures and have it show the size needed so I can print it out?
Here is my situation: I’m in the northeast, Boston, Massachusetts area. Six room Ranch built on a slab/no basement, 1056 sq ft. Attic insulation R-30, ductwork insulated to R-6. Exterior walls R-6. Windows low-e glass argon gas-filled double pane. Any basic help out there? Thank ya’ much.
ethx: I should have put the words “fancy calculations” in quotation marks. I have read it is the right way to do it. What I meant was the “pros” I have spoken with, including the one doing my heat, brush it off as nothing to be bothered with, they “know” how to figure it.
So, I don’t think there is a basic answer to my basic question….is there a basic, easy formula for me to use to get a basic, rough idea of the size needed.
Leslie
January 30th, 2010 at 3:44 pm
Wilburn
What you may want to do is contact your local plumbing supply shop for a free heating/cooling loss. Also it may be a good idea to add to your system. If you need 1.5 tons go to 2 tons for more efficency.
February 1st, 2010 at 12:41 am
Hassie
Actually the “fancy calculations” are there for a reason. The best person you can ask is your heat guy. He has already figured all this out when sizing your heat system. In any case though NEVER try to use a bigger system than your home calls for. If you use a bigger system you run the chance of the refrigerant not vaporizing as it should. It will work great at first but then you will get liquid back to the compressor over time and cause it to fail prematurely. You want your new system to last a long time, right? This is something you dont want to second guess. Let the pros help you. Anyway, hope I helped.