At any rate, I called an A/C guy, and he said that, when I pay him money, he will replace my central heat and air with a 4-ton unit.
So, the last time I had to buy any kind of CHA system was in the mid-80s, for a small 700 sq. ft. house, and, IIRC, on the bill was listed “40,000 BTU’s”. (I could be way off on that, but, I’m just putting that number there for filler.) There was no mention of tonnage.
I told the AC guy to put it in, and he said he’ll be here next week. I was outside with him while he was inspecting it, and I marvelled at how small the heating/cooling apparatus proper was. I liked the price he quoted, but, I rather staggered when he told me I would be getting a 4-ton unit. I envisioned myself wearing a parka in the middle of summer just to avoid frostbite, since the old unit couldn’t have weighed even 1/2 ton, so, the new one would be 8 times heavier, ergo, at least 5 times cooler (yeah, right).
Alright, I’m pretty certain that a 4 ton unit doesn’t mean how much the whole thing weighs. He would need some monster truck just to get it to my house, let alone install it.
Therefore, my question is: What does a ‘4-ton unit’ mean, in relationship to home central heat and air?
You want the right size unit for your premises. Too big will waste energy as well as too small. The right size hits a sweet spot for turning on and off. Get a good brand (Trane or Lennox were what I found when I did research) and have them check it at least once a year.
Assuming you’re in the South, which if I recall correctly you are, that is a bit on the large size. Depends on your home and how well is resists heat, of course (is it shaded?)
Too large is worse than energy inefficient. An A/C does two critical things: cools and dehumidifies. 78deg and 100% humidity isn’t comfortable at all…
If your A/C is too large, it won’t circulate enough air to remove the water.
It is always a balancing act. Smaller is better-as long as it is just big enough for the hottest days. In general, it is better to be uncomfortably hot a few afternoons a year than uncomfortable for most of the year because the A/C isn’t drying the air.
And while it depends on the house, I would think 4 tons for a 2000 sft house is too large. 3 tons sounds more like it. But it depends. Getting a good A/C guy who can make the right recommendation is the hard part.
I think a 4 ton unit might even be a bit small for 2000 square feet but it depends on a lot of other factors.
Personally I would trust the professional on site rather than random opinions on a message board.
The link article explans that one “ton” of cooling capacity is equivalent to 400 cubic feet per minute (CFM) of air change.
Unless this is somehow standardized, I don’t see that that necessarily follows. It might be standard in the particular machines they sell, but these seem to be so many other factors. Shouldn’t temperature change be mentioned in there somewhere? I can easily imagine moving 800 CFM of air, and cooling it half as many degrees.
Hummmmmm, I just might start a thread on the best way and the correct things to do to make the most efficient use of what ever A/C you already have on a daily basis. Not adding stuff, just how to leave doors, set thermostats, etc. … That would help manny peoples …
I have a 1300 square foot house with 8 foot ceilings. Built in 1952 with block construction. The A/C is a 3 ton. We do tend to keep the thermostat at 80 in the summer and with a ceiling fan in every room it is comfortable (as long as you are dressed for it - shorts and tees). I think the usual rule is 1 ton per 400 square feet. If you have higher ceilings or less insulated walls/roof you might want to get a bit more. I know some of the longer (more sprawling?) ranch houses around here have 2 a/c’s - one for the living areas and one for the bedrooms. Then you can adjust the temp in each area as you need it. Each A/C would then be a lower tonnage.
Done properly, there is a complex formula (forget the name) the HVAC guy is supposed to calculate - it takes in house size, # of stories, directional orientation (N, S, E, W), shading. Then we get into room size and does it have a window? How large? Which way is it pointing.
But they just look at the plate on the old machine and swap it for the same size.
