Replace & Move HVAC from Closet to Attic

9,322 Views | 7 Replies | Last: 5 yr ago by rondis23
GCRanger
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AG
We have a 2100 sqft 1 story 4/2 rental house in SA that is about 60 years old. We plan to remodel and move into it as our final home in a couple years. We are thinking of doing some base work in the meantime either between renters or while the renter is not there. The current renter travels a lot and is gone for a couple weeks at a time. The base work includes updating exterior and interior electrical panels and wiring (in-wall wiring to be replaced during remodel later), window replacement (most are original single pane), insulation (practically non-existent), and HVAC. This post is specific to HVAC. I'll likely be back with questions about other work as the time comes.


The current HVAC system (interior and exterior units) are at least 11 years old but in good working order. However, they will likely need replacement in a few years and if we replace them a bit early I'm not too hurt. The attic duct may not be original but it's probably 30 years old. The inside unit is in a hallway closet right next to all the bedrooms. The return is in the wall at the floor below the unit. The exterior unit is on a slab near the windows to two bedrooms. It gets direct sun until about 3PM.

Reasons for replacing and moving to attic
- Newer more efficient system and duct
- The system will be nearing end of life and all the duct work is going to be re-done anyway
- The closet is in is in rough shape (see pics) and has what looks like mildew
- Reduce noise in house around bedrooms
- Free up space for a hall closet as the current hall closet will go away when we remodel master bath. The current closet space will becomes part of walk-in shower (hopefully steam shower depending on $)
- Move return to a better location for better circulation, possibly more efficient. (this is all assumption on my part)

New location in attic
My preferred spot for relocation is on the other side of the house from current location. New location is above garage and laundry room above load bearing wall. It's away from living space so should be quieter. I assume this is best spot for it as it has structural support, the attic already decked in this area, easy access from garage attic stairs, and close to all hookups. The one gotcha is maybe too far away from living space to have efficient return location, more duct work needed.

Considerations and Costs
- New interior and exterior units - $3-$5k
- Minor structural support built in attic to put the new unit - $200
- Move exterior unit by the garage (bonus, it will be in shade all day) pour new slab and run lines. - $500
- Re-route electric, gas, water lines all of which are closer to source with new location in attic - $1000
- New exhaust vents through roof, and patch/close up old ones - $500
- Add new return location (ceiling dry-wall work) - $200
- Replace and rerun all duct - $2-$3k
- Re-mod old HVAC closet into usable hall closet - $500
- Efficiency is worse with it in the attic but most newer homes do it this way so I assume it would be okay.
- Future remodel may include hiding vising load bearing headers in the attic in a couple spots which may require duct to be re-routed a bit.

I'm thinking $11.5k at the high end to get this all done? We were likely going to spend $5-$8k to upgrade and replace in its current location so ~$3k more seems reasonable to move to the attic.


What are we not thinking of?
Is the cost in the ballpark?
How much time do you think it would take a contractor to do this?




Current A/C location in hall closet
https://imgur.com/XujFiJ8
https://imgur.com/CwrHkFm


Potential location in attic
https://imgur.com/FCg4Djq

Old duct work
https://imgur.com/L7EKcc4

sts7049
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AG
you ought to budget for some more insulation in the attic while you're at it. looks a little thin up there.
GCRanger
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AG
That is definitely in the budget and near the top of the to do list.
p_bubel
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I do believe, and I could be very wrong, that the drain line now needs to be routed to an actual drain here in San Antonio. So, going to need to run the line to either the bathroom, laundry or kitchen. There's probably an issue with the return I bet. I would assume that needs to be in the middle of the house.

Completely idiotic, but I'm going to have to deal with this too.
GCRanger
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AG
Should be able to get the drain to laundry relatively easy.
Aggie1
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AG
moving an A/C cold evaporator coil unit to the hottest part of a house into the attic when it has a cooler home already in a hallway is not economically efficient. the logic to move the condenser/compressor out of the sun is good but of course will require moving major copper.
the duct work does not look bad in the attic in the pics and can have additional insulation if that is a problem or there are leaking joints?
Unless you have black mold in the ducts I would leave them alone. some "dust" will often collect at registers from the air foil and collect much like on a fan blade. Be sure it's black mold before deciding this is an issue.
Replacing the evaporator coil unit inside and plenum will resolve the "ugly" you cite.
It appears you can save a ton of money by adding insulation to attic and replacing A/C unit in kind.
If your unit is properly drained in its present location good. But, to add a drain into a proper line plus a second drain as overload from pan to exterior from attic location means additional plumbing.
Running electrical to new location can be very expensive - will the run require additional sizing due to distance?
the AC closet can be sound proofed a lot cheaper than moving the unit.
relocating a heavy unit over a garage that probably is already ceiling joist load stressed is not a good idea without a LOT of additional structural support.
You will pay a premium for installation in an attic space - especially in the summertime.
Providing a return to the ceiling in the garage may be awkward and difficult to achieve and require at least a partial double duct system - thereby causing additional cost.
If the existing unit is "central" to the distribution and return it is maximizing the duct sizing. Moving to a far corner means bigger ducts, longer service, and possibly a bigger unit to push the air further?

I have had two house fires in my lifetime. Both came from A/C unit in the attic. I have also had pan failure and ruined ceilings from condensate running over instead of out clogged drains. The added heat load on units in an attic is tremendous and reduces its ability to perform well and economically. Glad to PM me for additional thoughts.
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Ribeye-Rare
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AG
Aggie1,

I enjoyed your thorough arguments in support of placing the air handler in a closet, as opposed to an attic.

Everything you said makes sense.

I would add that closet air handlers are tremendously more pleasant to work on! Minor electrical parts will need replacement and eventually (hopefully many years) so will a coil. Doing that in an attic? Not for me.
GCRanger
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AG
Aggie1, thanks for the detail. I hadn't even thought about soundproofing. That changes things a lot, as the noise is more my concern than closet space.

We'll have contractors inspect the duct to see if there is black mold or a real need to replace.

Another thing I hadn't really thought about was spray foaming the attic and making the house more efficient that way instead of traditional insulation.

rondis23
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AG
I'm not a contractor, or an hvac person. But I would definitely just spray foam the entire attic, and upgrade the current ac system. Seems more economical and efficient.
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