Window air - how big?

[5030tinkerer]

I have a 15000 BTU window unit in my 800 sq ft garage with 11 foot ceilings. The garage has R19 in the walls, R30 in the attic, and two insulated 9x7 garage doors rated at R6. If I had to do it again, I'd be purchasing a larger unit. It just takes too long to get the temperature down to a comfortable level. The coolest the unit will drop the garage to is 77 when it is 90 out, even it is run all day.

 

[jinman]

Fishman, do you remember that little cabin on my place? It's 480 sq ft. It's insulated with R19 and the ceiling is drop-in tile which adds another layer of insulation, but there is no insulation in the floor. I bought a GE 17,500 btu unit to put in there and it did a wonderful job of cooling. I can't imagine your garage needing less. I put in a 30 amp circuit and it was plenty for the AC.

If you could mount your AC in the garage up high, it will do an even better job of cooling. Down next to the floor, the intake pulls cool air back in. Up high, the cool air drops and the intake air is warmer.

Have you seen the kind of AC window units that shut down the blower between cycles? I saw one recently and was surprised because I'd never seen one. If I ever buy another one, it will be one of those.

I think you can cut costs on a window AC unit and end up with something you won't be happy with. I'd spend a little extra and make darn sure I have enough cooling to combat this brutal heat as AlanL stated.

 

[fishman]

This has given me lots to think about. I really appreciate everyone's input on this. A bigger unit will require 230, but that may not be a bad thing, because it will free up my 120 circuit for other things.

 

[Bird]

</font><font color="blue" class="small">( Have you seen the kind of AC window units that shut down the blower between cycles? )</font>

Jim, my Whirlpool, mentioned above, has that feature. They call it the "power saver" setting on the switch.

 

[jinman]

</font><font color="blue" class="small">(
They call it the "power saver" setting on the switch. )</font>

I call it the "ear saver" because there is nothing quite as noisy as a window AC's fan...unless it's a jet on take off roll. /forums/images/graemlins/smirk.gif

When I had to turn the AC on in the summer, that was the last of wildlife I could hear outside my cabin. I love listening to the sounds of whipporwills and bobwhite quail. /forums/images/graemlins/smile.gif

 

[Sigarms]

You'd be surprised how much I don't know about A/C /forums/images/graemlins/grin.gif

You may be right on Texas weather, I don't know.

Couple of years back working on the inside, did about 400 load calculations a year (Wrightsoft) and only had four that came back due to issues (due to change in work order on the structure, contractors can be a pain to deal with).

What I will say though is that if you have a good HVAC contractor, and he does his job right, if he gives you a load for the structure and it doesn't heat-A/C properly, he would change the system out at no charge (there is "fine print" there) homeowners can be interesting dealing with temperature (keep in mind, changing the load may also require changing the ductwork, which alot of times never happens).


I deal with a couple of contractors who do this on a regular basis, may charge a little more than just a "change out man", but so far these people have never had to replace a system due to the load requirements of the structure.

Considering the fact that Centex homes, Lennox, Goodman and American Standard have home offices in Texas, I would be curious how load calcs are done down there.