Refitting HVAC

kaiser715

kaiser715

Doing hard time
Joined
Jun 1, 2006
Location
7, Pocket, NC
We found a house that is interesting, on some acreage. ~3500sf total, all brick, with partially finished basement.

It was built in mid 40's. Heat is hotwater baseboard (nat. gas boiler), and a/c is window units in some rooms. Basement ceiling is 2x4 tiles. Attic is a walkup, partially decked for storage, pretty open.

So, is it even worth considering putting in central air/heat? I know it's a big project, but are we talking $15k, 30k, or what?

House needs a heck of a lot, but very solid, just way out of date, looking at having to put around 75-100k +/- into it (repl. windows, paint, roof, etc), and will still come out ahead.
 
15k should be the high end for two 5 ton systems with all new duct.
 
XJsavage said:
15k should be the high end for two 5 ton systems with all new duct.
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This would be my answer down here. I hear that yalls prices are through the roof right now though.

You've got $8-10k in equipment there. Maybe a $1k in ductwork in materials. Then a bunch of labor.
 
XJsavage said:
15k should be the high end for two 5 ton systems with all new duct.
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But if you are retrofitting it to a 1940 house that has never had ductwork, that $15k can be a low estimate not to mention what you will run into when running duct. Oh, and you may have asbestos to deal with when running duct.
 
Ron said:
This would be my answer down here. I hear that yalls prices are through the roof right now though.

You've got $8-10k in equipment there. Maybe a $1k in ductwork in materials. Then a bunch of labor.
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Yeah thats a ballpark South Carolina price. The company I work for would be anyways. The height of the crawlspace/Attic and supply to return ratio per system is what sets the final price along with number and skill of techs dispatched.
 
Don't run duct or locate HVAC equipment in an unconditioned attic.

That said, ten tons sounds like a shitload of cooling... but I guess if it has shitty windows and no insulation... maybe.

Our 2700ft 1962 house only has a 4-ton unit.

I was going to guess $20k.
 
shawn said:
Don't run duct or locate HVAC equipment in an unconditioned attic.

That said, ten tons sounds like a shitload of cooling... but I guess if it has shitty windows and no insulation... maybe.

Our 2700ft 1962 house only has a 4-ton unit.

I was going to guess $20k.
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Yeah, caught me after a long day at work. 2 ton and 5 ton is what I was visualizing and trying to say.
 
On a related note, I've been looking at used splits on Craigslist. Entertaining the idea of replacing our package unit with a pair of splits. Might never go anywhere, but I have the bug in my head now.
 
shawn said:
Don't run duct or locate HVAC equipment in an unconditioned attic.

.
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Just curious as to why? I saw many house when we were looking that had the hvac unit in the attics (mostly heat pump systems) and those soft insulated duct work up there also.

Thanks.
 
BRUISER said:
Just curious as to why? I saw many house when we were looking that had the hvac unit in the attics (mostly heat pump systems) and those soft insulated duct work up there also.

Thanks.
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Unless the ductwork itself is well insulated, you end up losing a lot of the duct air temp to the elements.
Although Shawn probably has a more complicated answer.
 
RatLabGuy said:
Unless the ductwork itself is well insulated, you end up losing a lot of the duct air temp to the elements.
Although Shawn probably has a more complicated answer.
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That's more or less it. The attic can get to 150F in the summer, but you're trying to run 65F air through it. There's the loss while the unit is running, but the loss when it's not running is probably a bigger concern. The air handler itself isn't really insulated, and the flex ducts are only R-8 (at best), so the whole system is filling up with 150F air in between cycles. Then the fan kicks on and it blows all that hot-ass air down into the house.

Winter time is probably less of an issue, but I would bet that nighttime temps in the attic get well below what you'd see in a crawl space. Probably easily get into the 30s and 40s if the attic is ventilated and reasonably well insulated.
 
shawn said:
That's more or less it. The attic can get to 150F in the summer, but you're trying to run 65F air through it. There's the loss while the unit is running, but the loss when it's not running is probably a bigger concern. The air handler itself isn't really insulated, and the flex ducts are only R-8 (at best), so the whole system is filling up with 150F air in between cycles. Then the fan kicks on and it blows all that hot-ass air down into the house.
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So I'm curious, I've read a lot about pros and cons of insulating the ceiling (under the decking) instead of the joist space of the attic.
If you're in a situation where it really is more cost effective to run the HVAC up there, do you think it's better and more cost effective to change to an insulated attic to boot?
 
Lots of good reasons to insulate at the weather barrier rather than at the edge of habitable space. "Cost effective" is a tough call. It's going to cost more to insulate at the roof rather than the ceiling, regardless of how you do it. It's also a lot harder to do it right. Let's say you hung R-30 batts tight to the sheathing. It's more SF than putting it in the ceiling (sometimes a whole WHOLE lot more), but the dew point shifts down under the sheathing. So you're going to end up with rot and mold.

At the very least, I'd try to get the air handler into conditioned space. Even if that meant leaving out the insulation separating it from the rest of the house, then insulating all around it to make a little "room" that was part of the conditioned space.

But there's no perfect answer. I've seen attics that were big enough to park a couple of airplanes in them. Sure as shit don't want to be coating the underside of all that roof sheathing with closed cell poly.
 
Is it possible to put everything in the basement instead? That's pretty common in many areas with older houses. It's a conditioned space, even if it's not directly climate controlled.

Full length basement? Dunning floor ducts will be easy if it is.
 
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