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What is my best solution to remove HVAC & ducts from cold attic?

SouthDakotaRoof | Posted in Energy Efficiency and Durability on

I bought a home 7 months ago. 1953 ranch style, 5 on 12 gable roof, 2 gable vents, 4 “turtle” vents on southern side midroof & supposedly soffit vents. Add in a hvac and flex duct that was never sealed and about 4 inches of beat up kraft faced fiberglass laying willy-nilly over the original loose fill (I’m guessing its rockwool?) Attic floor has never been air sealed. And of course all of this is in cold climate 6a. This is how we roll in South Dakota, yee haw. The very moment winter started I realised my home has severe heat issues and thus my self education for survival in this new house began. I never heard of ice dams, attic moisture issues, didnt even blink when I was told hvac was in attic. Ha! Anyway I’m air sealing attic and installing baffles currently. Im snaking a camera into the formerly insulation blocked soffits, I have yet to find any actual venting holes in the wood soffit that my aluminum vent panels cover. I’ll add insulation when I’m done sealing and baffling. I’ve discovered i have two layers of ceilings pressed together, I think only in some areas (WHY WOULD SOMEONE DO THAT?) so I cant get at the interior top plates for air sealing? Any special instructions for this weird situation? I am able to get exterior top plates, duct boots, etc and so forth. I’m currently gathering roofing estimates to add in soffit vents & change current venting. So far the roofing companies either admit to not understanding proper venting (yay for honesty!) Or they propose venting options I know are wrong from reading your site. What would you suggest for venting my 873.8 sq ft attic? (House/attic is L shaped). My next project will be to remove the hvac & duct from my attic. My nice finished basement has more than enough room. I understand this will be a very expensive project. Question is, if I’m ready and prepared to write some serious checks for improving my home heating and air system- should I be looking beyond just moving the unit and ducts? Now, dont get super crazy on awesome ideas that cost intense amounts of money. I honestly dont know yet what a reasonable price tag on just moving and reinstalling by itself is. 5k-15k? Ick. But let’s say I’m willing to invest up to 25k or so doing something wise which gives eventual paybacks. I assume I’ll live in this home for the next 40 years until my daughter starts eyeballing retirement homes for me. What would you suggest for my heating situation? Thank you for all that you do with this website!

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  1. user-6623302 | | #1

    How about some pictures of the outside so we can understand the layout. How is the house heated and what are your fuel options?

    1. SouthDakotaRoof | | #4

      Hi Jonathan
      The house is heated by my attic hvac which uses gas. As for my fuel options, I'm not sure exactly what you are asking there? Sorry, I am undereducated in these things and I'm sprinting to catch up. Bear with me please?

      1. ohioandy | | #5

        Trina, you answered the question with that snippet from the inspector's report. Your furnace is natural gas forced air. (Fuel options means oil, propane, gas, electric, wood, etc.) The location of your furnace seems a little unusual for the northern climes when you have a full basement (it's "how they roll" in the south when houses are on slabs.) But your initial horror is well grounded. It's a TERRIBLE place for the furnace and ductwork, for the sake of efficiency and for ease of access. Trouble is, doing anything about it will be very expensive. But if you're in the house for the next 40 years, it may be wise to do it now since you have the means. There are a few variables which will determine what's best to do.

        A one-step fix is to move the house's thermal barrier to the roofline, as has been suggested, but that's neither cheap nor simple. Doing it all from the inside (spray foam, then batts) is very difficult considering the low roof, and a code-minimum R49 would be tough, especially at the eaves which probably have less than 6" of clearance. Ideally you'd install at least SOME of the foam above the roof sheathing, but now you're adding in a total re-roofing job with trim modifications. With those options, at least you don't have to do any attic floor air-sealing. (Your description of the double ceiling situation is unclear. Send a pic or describe in more detail.)

        The other option is to relocate the furnace, probably to the basement. In addition to creating a place for that, it requires an entirely new set of ducts. In you finished basement this may be a challenge. And you'd STILL want to do that attic insulating and sealing work.

        Another option to consider (my favorite) is abandoning gas and moving to electric minisplits. This eliminates (or drastically reduces) ductwork altogether. This option must be paired with improvements to your house's air-sealing and insulation, which you've already started.

        The most important factor you'll have to consider is your access to knowledgeable and conscientious contractors. If they're not already on board with what you're trying to do and the science behind it, you will come to grief. GOOD LUCK and keep asking questions--these are the questions America should be asking.

        1. SouthDakotaRoof | | #9

          This first photo was taken standing on a ladder in my living room, my head and shoulders popped up into the attic hatch. You see the bathroom there. That attic duct boot goes into that bathroom. There is no top plate between me & the boot as there should be. The bedroom next to that bathroom has no top plates either, nor does the bedroom just at my back. 2nd photo is... I'm not sure, a square someone cut? I think that wood uncovered is one of the missing top plates. Never heard of this before? Also just as a info up date- there is a. Maximum clearance of 17 inches from hvac to roof. Hvac is directly on joists, and the duct that goes to a chase down to my basement- it actually touches the roof. Yup, we do things special here. :) ok so, two ceilings have been confirmed enough? Any special airsealing I should be aware of due to my unique circumstances?

  2. chrisjri | | #2

    I'm no professional but I would look into insulating the underside of the roof plus rigid insulation on top of the roof. Then the hvac would be within the conditioned envelope of the house.

  3. Expert Member
    Akos | | #3

    I think Chris' plan is the best here. Relocating the HVAC is very expensive, it would only be worth it if you are doing major reno work.

    Spraying the roof with 2.5" of closed cell foam followed by a 2x4 batt would give you a roof that has 2x the R value of your existing insulation and also get your hvac into the conditioned space. You can go with more SPF and thicker batts, but the cost increases quickly and the energy savings is not that much more.

    If you need to re-roof, going with exterior rigid insulation would probably be cheaper than the spray foam solution.

  4. lookloan | | #6

    Because it is an existing home, I am not sure the R-49 roof insulation requirement exists, meaning the R-49 is for new construction.

    1. ohioandy | | #7

      In much of the country there is no code enforcement, that's true. A certain level of energy efficiency can be required, aspirational, or a no-brainer minimum; I hope most readers here already agree it's the latter. And then do the best they can.

      1. SouthDakotaRoof | | #11

        Oh no honey, I'm in town. :) im in the second largest city in the state. This is as good as it gets. Of the 4 top roofing companies I've had in this week to give estimates for soffit vents, only 1 company ever heard of the 1/300 or 1/150 vent guide. I had to instruct legitimate companies on venting. And honey, as you can tell, I dont know much at all. The seemed to think I was coming up with crackpot internet theories. Yup.

  5. user-6623302 | | #8

    How do you heat the basement? How old is the furnace?

    1. SouthDakotaRoof | | #10

      Furnace is about 10 years old. The basement gets a duct run down through a chase that splits into 3 vents. Basement doesnt get much heat at all. It's that duct in my above photo that touches the roof. And the ducts nor the unit had ever been sealed before me. I've been slopping mastic on everything as I'm working in the attic. My electricity bill is outrageous! Plus the previous owner worked for the electric company so he decided what this house was missing was ridiculous amount of additional lighting including can lights that of course, were never sealed or covered. Hehe, it's amazing how it keeps adding up.

  6. bennettg | | #12

    Trina, it seems pretty clear that resolving the HVAC in attic issue is not going to be cheap. Thinking outside the box for a moment, what would it cost you to sell this house and buy one with the HVAC in the basement?

    I think it's "how they roll" everywhere. Here in the south, it's vented, moldy crawlspaces, ac in the attic, bath fans vented to the attic, poorly flashed if at all windows and doors, etc. A previous house had all that and the soffit vents screwed on with no hole as you describe.

    Good luck with your project or finding a better one.

  7. 730d | | #13

    What is my best solution to remove hvac & ducts from cold attic?
    The answer is to just do it. If you put a forced air furnace in the basement and remove everything from the attic and insulate your attic with a reasonable amount of ventilation
    you will be twice as comfortable using half the energy. Two times two is four. Four times better and your building will last a one hundred years . This is much harder if you had a slab on grade. You have a basement. Unbelievable this was constructed in a northern climate.
    Also . In my opinion. Don't insulate your rafters and and condition the attic. Will cost more and perform poorly. Ice dams. Sorry for the attitude.

  8. ohioandy | | #14

    Mike, yikes! It's just not that simple. Two times two does equal four, but that's not a Manual J load equation. Trina already said the contractors in her area, like most places, are not interested in doing things differently, to say nothing of a grounding in building science. So she may hire out this work--having already said she's willing to pay a premium--but may end up with a system that's better located but poorly designed, overpriced and oversized, has no net payback and does not improve comfort. She's not gone into detail on the condition of the rest of the house's thermal envelope. That's tough at best--not a straightforward fix in a 70-year-old house.

    And Mike, like ALL strategies, roof insulation CAN be a total flop, or it can be the smartest way to go. It depends on many factors. She's going to have to find the sweet spot.

    1. 730d | | #15

      Thank you Andy of course you are correct. I am sorry Trina. Lots of very nice and knowledgeable people here. I know the climate there and and the year it was built. Those houses have good bones. The attic is low and miserable to work in. Spent my life in the business and jumped to conclusions. Sorry, maybe I am wrong but I think when all is said and done it will be best and cheapest to move the HVAC to the basement.

  9. user-6623302 | | #16

    This house is a major project. You need to upgrade the insulation and air sealing in the whole house including the basement which appears to have a large exposed above ground surface. I would look to move the furnace to the basement. No need to heat that unused attic. With these done, your current furnace is going to be oversize. Look at the new led light fixtures. Get rid of those cans. LEDs will save you 90% on lighting. This is a small house and should have a small utility cost.

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