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morbo
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morbo

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[HVAC] Move a/c unit & ductwork from attic to basement

I have an a/c unit and ductwork in an 80 year old house with some attic insulation. The problem is that it's an old house and is not well insulated (walls, windows, etc.). In the summer the system struggles to cool despite being serviced and using clean filters.

I recently read

»www.energyvanguard.com/b ··· he-Attic and

»www.nrel.gov/docs/fy10os ··· 8163.pdf

That emphasized how the best thing one can do for efficiency is move the a/c unit and ductwork inside the living space. My 2.5 ton a/c unit is 6 years old. I'm considering this option, but I want to hear some feedback on that choice. My biggest concern is cost.

How much would it cost to move everything and do a basement install?

Because my basement is not heated or cooled except by a single window unit, a possible advantage would be I could add a vent or two and a return to help make it a more usable space.

aurgathor
join:2002-12-01
Lynnwood, WA

aurgathor

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Personally, I would just add some insulation around the ducting.

morbo
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morbo

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I'm certain that is cheaper, but does it accomplish the same thing as these reports indicate moving everything to a conditioned space?

robbin
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join:2000-09-21
Leander, TX

robbin

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Another option would be to move the attic insulation to the roof using sprayed foam thereby making it conditioned space.

cowboyro
Premium Member
join:2000-10-11
CT

1 recommendation

cowboyro to morbo

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to morbo
I can see the entire thing being in the $10k range depending on the layout and basement access.
The cost involved with moving everything will likely never be recovered. I would guesstimate your losses at no more than 4500BTU/h in the most unfavorable conditions, that's in the $0.05/h range with a decent A/C unit based on $0.15/kWh.
You do the math... moving the system for even $5k for saving less than $0.5/day.

SparkChaser
Premium Member
join:2000-06-06
Downingtown, PA

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Is your AC a high velocity unit, like mine. It's in the attic and I'm sure it would do better somewhere else but it's the only place it fits in this house. You may run in to the same problem.

John97
Over The Hills And Far Away
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join:2000-11-14
Spring Hill, FL

John97 to morbo

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For what it would cost, you could probably buy a ductless mini-split system (or two) and cool the common area(s) of the house most of the time.

For a lower cost option, I agree with aurgathor regarding insulating the ductwork.
kherr
Premium Member
join:2000-09-04
Collinsville, IL

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I had to move my ductwork from the basement to the attic. The furnace is still in the basement though. I buried my duct in insulation. I went up to add some wiring and after 20 years and the flex is still in good shape.
TheMG
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join:2007-09-04
Canada
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said by morbo:

The problem is that it's an old house and is not well insulated (walls, windows, etc.). In the summer the system struggles to cool despite being serviced and using clean filters.

I think the answer here is obvious... if the walls and windows are poorly insulated and a major source of thermal losses, I'd look into improving the insulation.

As for the ducting, you can add insulation on top of it.

Anything you do to the ducting will only make a small difference, since the insulation (or lack thereof) in your walls is the main problem.

netboy34
Premium Member
join:2001-08-29
Kennesaw, GA

netboy34 to morbo

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Personally I would spend the money on new windows and more attic insulation...
99556139 (banned)
join:2013-02-14

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I'd say the most economic way would be to leave the a/c and concentrate on fixing the insulation, as you'll see more results from this. However great the job is, if you have poor insulation no amount of efficient a/c is going to help.

morbo
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morbo

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I appreciate all the honest feedback. Thanks everyone.