Properly sizing central A/C
Posted: Mon Jul 14, 2014 7:06 pm
I was wondering if there's a guide to properly sizing a central A/C system.
I have a 14x66 with a 14x12 addition (so around 1100 sq ft.) My A/C furnace supports up to 3 ton capacity as far as I remember. Built in 1980, so 2x4 walls. R14 in the walls, R22-24 in floor/ceiling. I discovered the addition was pretty piss-poor done construction-wise, and reinsulated all the walls and ceiling, then found out there was none in the floor, so I did that too and put belly tarp there. There are heat ducts that I ran to the addition although the airflow isn't less than I thought it'd be, I probably should have put a baffle in the main duct to direct some air into the 6" pipe that runs to three vents in the addition. Hindsight is always 20-20.
I live in a climate where four months of the year it can get pretty warm (between 30 and 35 C or 85 to 95 F) with decent humidity, usually between 45 and 80%, but it can get higher.
I just want to do some calculations myself so when I get some quotes for a new compressor and evaporator I can tell if they're out to lunch. The reason being is I used to have a 1972 12x66 and the local guys sold me a one ton cooler and if it got over 30 C it couldn't keep up, a few times on the 35 C days it could only cool to 28/29C running nonstop.
Anyone got tips?
I have a 14x66 with a 14x12 addition (so around 1100 sq ft.) My A/C furnace supports up to 3 ton capacity as far as I remember. Built in 1980, so 2x4 walls. R14 in the walls, R22-24 in floor/ceiling. I discovered the addition was pretty piss-poor done construction-wise, and reinsulated all the walls and ceiling, then found out there was none in the floor, so I did that too and put belly tarp there. There are heat ducts that I ran to the addition although the airflow isn't less than I thought it'd be, I probably should have put a baffle in the main duct to direct some air into the 6" pipe that runs to three vents in the addition. Hindsight is always 20-20.
I live in a climate where four months of the year it can get pretty warm (between 30 and 35 C or 85 to 95 F) with decent humidity, usually between 45 and 80%, but it can get higher.
I just want to do some calculations myself so when I get some quotes for a new compressor and evaporator I can tell if they're out to lunch. The reason being is I used to have a 1972 12x66 and the local guys sold me a one ton cooler and if it got over 30 C it couldn't keep up, a few times on the 35 C days it could only cool to 28/29C running nonstop.
Anyone got tips?