A/C replacement question...

[Whoaru99]

My central AC is old...dunno how old, but old. It has been needing to have R-22 added every year for the last three or four years and does again need it (freezes up the evaporator after running for a while). Yes, the coils have been checked and they are clean. I'm not sure the size because the label is sunbleached completely white, but I believe it is either a 2T or 2.5T unit.

So, anyway, I'm thinking of replacing the whole thing...outside unit, line set, and evaporator coil. I've done some of the online calculations and come up with about 20,000 btu. Of course, in central air, there is a 1.5T (18,000) or a 2T (24,000).

My gut reaction is to get the larger 2T unit, but at least one person told me not to go larger (in other words, get the 1.5T) because the 2T will cool the house too quickly and may not remove the humidity as well because of the shorter run time.

I could see this being a concern if I went with something really oversized like a 2.5T or 3T unit, but is this a real issue by just going up to the 2T unit for an estimated need of 20k btu?

EDIT: BTW, I often do have extra electronics running for TV/home theater...50" plasma, several amplifiers, etc.

[WallEYES]

A general rule of thumb for sizing equipment is figuring 800 square feet of conditioned area per ton

[Whoaru99]

Since my house is fairly small, ~925 sq ft, that would tend toward the lower ton unit.

That said, the online calculator I used did factor in window/glass area, exterior wall area, which direction the windows and walls face, if kitchen area is included, etc. I filled in these ten or so questions accurately and that's what spit out the ~20K btu requirement.

Mebbe I should just have someone come over and do a heat load on it since it shouldn't add much to the overall cost?

The current thought is to buy the new stuff, DIY install, then have a HVAC guy solder the lines and evac/charge the system.

[jeffreyd]

i would have someone come in and then look at your power company and the federal websites to see what incentives are out there for new a/c. if you can afford it, go with the new gas, r410 vs the r22

[Whoaru99]

I've looked a little bit at the Federal incentives, but the units I've looked at so far all call for two-speed or variable speed blower control to get high enough efficiency to qualify. My old furnace doesn't have that and I don't really want to pop for a new furnace AND new central A/C right now, seeings how I primarily use electric plenum heat anyway.

Actually, though, since the furnace is at least as old as the AC, maybe older, it should be replaced too. Again though, since I don't use the burner, just the blower with the plenum heaters, it hasn't been a pressing issue.

Maybe I should just save my pennies and pop in a couple (relatively) cheap window AC units for this year and do it all up right next year with new furnace and all???

[nofishfisherman]

Any rough ideas on what a 2T unit would cost? Found out today my unit is dead. The guy who came out gave me an estimate of $3,400 with installation. Just wondering if that's reasonable. I will of course be getting other estimates but it might have to wait awhile since I don't have that kind of money laying around.

[spearchucker]

I would still check into getting the whole system installed (furnace and A/C). You might be surprised how cheap it is with the manufacturer rebates and the 1500 tax credit. The newer furnaces have better blowers and more efficiency which help heating and A/C. I replaces a 33 year old system and am glad I did.