1989 condensing unit, air handler in attic

[Bradfurd]

Our house is a ranch from the 70s with electric baseboard heat and a cooling only outdoor unit (from 1989) with the air handler in the attic and flex duct to all of my ceiling diffusers.

We are considering replacing this setup, and sticking the new air handler in the attic is my only realistic option. Our basement is already finished and there is no room for a garage installation. Looking for tips/recommendations...

Should we replace in kind and continue with electric baseboard as our primary heat source or replace with a heat pump and abandon the baseboard? I can vouch for it being expensive! Do rooms struggle to get warmed up when the supply is in the ceiling?

Also, my only access to the air handler is via the ceiling return in the hallway or a 2x2 hatch on my back porch. Do new air handlers typically get delivered and installed in one piece?

Thanks in advance for any tips or feedback!

[Papa bear]

What part of the country do you live?  That makes a huge difference. 

And then we’ll come back with 100 more questions about your insulation, venting, etc.


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[bmjohnson35]

I agree that you need to provide more details for more input on options.

As for the air handler, we bought an older townhouse with air handler in the attic for upstairs.  We bought a Trane unit that is a composite construction that was designed specifically for attic spaces.  I can say we are very happy with the unit. 

[SndcxxJ]

We routinely install heaters/air handlers in attics.  This area doesn't get crazy hot, but it is something to consider if you require a lot of cooling in the summer months.  The ducts and air handler are in an unconditioned area since they are in a vented space above the insulation.  The insulation on the ducts are probably r-6, which isn't much, the air handler is probably not insulated at all.  One option to mitigate this issue is to cover the ducts with more insulation, often by burying them in blown in insulation.
As for the attic access, code in my area requires the access to be 20"x30" and have a catwalk from the access door to the equipment.  This is typically a 2' wide row of plywood screwed to the tops of the joists. 
The rooms will most definitely heat up with the registers in the ceiling.
Why are you replacing this set up of yours?
I would ditch the baseboard heaters and go with with either a heat pump or a split system, but only if there is something going on such that this set up needs replacement as this will not be a cheap upgrade.  I would keep the existing ducts unless there is a problem with them.

[Papa bear]

Having a furnace/air handler in an unconditioned attic is really all around a bad idea. You lose something like 30% of your energy to leaky ducts and inefficiencies up there.  Now, you can be super careful and mastic all your joints and the seems, but it’s not perfect.  Spray foam over the entirety would be even better, but keeping it in a conditioned space is even better. 

I really don’t care about “leaky” ducts in a house where the HVAC is in the building envelope.  You’re heating or cooling a box. But heating/cooling an unconditioned attic, depending on what climate zone you’re in, can be damaging.  Cold climate, in the winter, you’re going to lose a ton of heat and you can cause some ice dam issues.  Hot climate, AC and you’re going to kill efficiencies. 

But we still need more info to give some decent advice.


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[Bradfurd]

Thanks for the feedback so far!

I am in the mid-atlantic, specifically central/western Maryland. I understand the inefficiencies, but based on the layout of the house, it is our only realistic and most cost-effective option.

I am mainly planning to replace the equipment due to age and efficiency concerns. It also requires R22 and we've had to charge it more than we'd prefer and just feel that it is a matter of time before we are left with a complete failure in July! The prospect of potentially eliminating our baseboard heat is exciting as well...but it's not a dealbreaker if it's best to keep it.

FWIW - I have an attic fan, vents in the gable ends, and a vented soffit. Current attic insulation is blown in cellulose.

[Papa bear]

You don’t have to do in the attic, you can do ductless minisplits based on your home layout.  There are plenty of options


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[Bradfurd]

I just got done doing a ductless mini split in my finished basement...very familiar with them. I'm certain it's not going to be cost effective or make sense on my main level. I have 3BR/2BA all within 1200SF, and getting proper distribution would be a challenge, as well as determining whether or not to place wall or ceiling units, routing condensate, patching existing grille locations in ceiling, etc. I've looked at geothermal, but the payback period just doesn't make sense for us.

I truly do not have the space to place an air handler anywhere else, short of buying a residential packaged unit and having it all outside! I see that they exist, but I'm not sure I've ever seen one. I do not want to sacrifice bedroom space for an interior duct chase.

Nonetheless, I appreciate the feedback thus far.

[Fishindude]

My two cents worth:

Electric baseboard heat sucks and HVAC equipment in an attic sucks for many reasons.   Mini splits are an option, but sure wouldn't be my first choice as you'll likely require multiple units, and have equipment exposed to view with these.   Flex duct also sucks, as it impedes air flow.  Insulated sheet metal duct is the way to go.

I would replace the entire works with a new conventional forced air gas (or LP) furnace with electric AC.   There is always someplace you can stick a furnace if you get a little creative, in an existing closet, build a closet, etc.   I'd try to get the air handler in the basement to take advantage of heat rising naturally.  Sounds like your location probably relies on heat more than AC.

[Papa bear]

Is this a ranch with basement?


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[Bradfurd]

Yes...just finished 1060SF of my 1200SF walkout basement...considered dropping the new air handler in my 140SF unfinished workshop, but space in there is already so cramped! I would have to route ductwork up through my kids' room to get to the attic...might be able to contain it in their closet, but would need to build a finished chase in their room if not. I'm concerned about the cost/time it would add and the amount of project/building space the air handler would occupy in my workshop. I already have my water heater, well tank, filter, UV light, storage, etc. in there. I guess it's an option worth considering...

[Fishindude]

Yes...just finished 1060SF of my 1200SF walkout basement...considered dropping the new air handler in my 140SF unfinished workshop, but space in there is already so cramped! I would have to route ductwork up through my kids' room to get to the attic...might be able to contain it in their closet, but would need to build a finished chase in their room if not. I'm concerned about the cost/time it would add and the amount of project/building space the air handler would occupy in my workshop. I already have my water heater, well tank, filter, UV light, storage, etc. in there. I guess it's an option worth considering...

If you put air handler in basement, there would be no need to ever run a duct to attic.  Abandon that old inefficient flex duct in attic and run new duct in basement with supply outlets through floor to service main living area.   The air handler will take an are about 3' x 3', but it will now be accessible for easy service, to change filters, etc.    Sure, you might have to rebuild some things, get into some ceilings, run new duct, etc. but it will be done correctly this time and last a very long time.   What's more important .... a few square feet of workshop, or proper heating and air conditioning?

Guessing your place was built without AC originally, baseboard heat only, then someone came in after the fact and stuck AC unit and flex duct in attic because that was cheap and easy.

[Bradfurd]

I hear ya, I do!

That plan has crossed my mind as well, but the dollars, mess, and time associated with an extensive reno (just finished my basement project, new holes in floor, patch holes in ceiling, tear up new basement ceiling, etc.) have me pushing that to the wayside.

I am on board with replacing the attic flex duct with insulated hard duct per your previous comment...you are probably right about the AC being put in later. I will think about this some more.

What do you think is causing more inefficiency - the air handler being in the attic or the duct being in the attic? If I decide to give up the workshop space to place the air handler and go with insulated hard duct in the attic, is that a win?

I have to spend a little more, but I don't have to have a major mess...just a moderate one. Thanks everyone!

[Papa bear]

I’d suck it up and carve out space in the basement and run it properly. 

The air handler and ducts in the attic is not only about inefficiencies.  You will be literally heating your unconditioned attic. That is terrible in the winter, can cause ice dams, water infiltration, etc.  you also have a TON of holes on your air sealing “envelope” which is your drywall ceiling.  That many duct openings really lets a lot of air into your attic space.  There’s a big reason these things are not in attics in areas that heat more than cool.  It’s bad. 

If you decide to keep it up there, you may consider encapsulating the ductwork and floor of attic in spray foam.  But from a cost perspective, build a closet in the basement and rip out some drywall.


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[Fishindude]

I’d suck it up and carve out space in the basement and run it properly. 

The air handler and ducts in the attic is not only about inefficiencies.  You will be literally heating your unconditioned attic. That is terrible in the winter, can cause ice dams, water infiltration, etc.  you also have a TON of holes on your air sealing “envelope” which is your drywall ceiling.  That many duct openings really lets a lot of air into your attic space.  There’s a big reason these things are not in attics in areas that heat more than cool.  It’s bad. 

From a cost perspective, build a closet in the basement and rip out some drywall.

/\ /\   This is the right way to do it.   /\ /\

If you want to save a little work, you could simply abandon the old flex duct in the attic, seal off each supply / return diffuser so they don't leak air into the attic, and leave the ceiling diffusers in place.   Remove diffusers and patch the drywall in ceiling at a later date when you re-paint those rooms.

[index]

I added a ducted mini-split in my attic last year. If you were doing a whole house you would probably need two units. We have an old house with no returns on the second floor and no good way to get a couple of returns up there. The new mini-split is 1.5 tons and covers three bedrooms and a bathroom (800 SF). I ran a return and sully to each bedroom and a supply to the bathroom. The longest supply run is 7 feet, one return run is about 14 feet and the other two are 4 to 5 feet.   

To compensate for the attic install:
We built a closet around my attic air handler insulated with r10 foam board and air sealed with expanding foam
R10 foam board on the supply and return plenum sealed with mastic
Expanding foam around all ceiling the registers
R8 flex duct stretched tight   
Mastic and zip-ties at all connections + foil tape
Blown insulation over everything - 18 inches over the ducts
The last step is commissioning the system and checking all the duct connections for air leaks and applying additional mastic if necessary

Overall our summer electric bill was down about $20 a month and this included maintaining the temperature at 74 each day instead of a big set back while we would usually be going into the office. We noticed the 1.5 ton mini-split keeps the hole house cool from the upstairs for all but the late afternoon on hot days.

The basement install is ideal, but I think you have to compare the cost of the attic versus basement. You are going to save money operating a heat pump over baseboard heat and an old 4 seer AC unit regardless of where you put it. You also may want to consider the option of a ducted-mini split for the bedrooms and an exposed head unit or ceiling cassette in the main living area. Mini-splits are DIY if you are willing to take on a big project and do some research ahead of time.

On a side note, I do not understand HVAC markup. The lowest bid on an identical system to the one I installed was bid at $10,500; a dual head wall mounted system was $8,800. The system + materials was about $2300 plus another $400 worth of tools. I would say total time invested including researching what to do was maybe 80 hours. 40 hours reading and 40 hours install. Plumbing, auto mechanic, electrician all run $80 to $130 and hour with a helper. The companies out said they could have 3 techs finish up in a day so maybe 24-30 man hours which is $300/hr for the crew. I don't get the mark up over the other trades.

[Bradfurd]

Thanks for the tips!