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  1. #1
    Join Date
    Feb 2012
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    Question Worth it to redo ducting/moving furnace?

    Hello all, I'm new here (as if you can't tell ). I am not a HVAC pro, but a home owner but would like to get some opinions on some plans I had in mind for the future. I am thinking of completely having the ducting and moving the furnace over. I apologize for the long post but think the details are important, so here goes

    Details on existing system and house:
    The furnace- 80% mid-efficiency Carrier natural gas (58WAV091-14), but its only 5 years old, so it should have plenty of life. House is 1950's with central heat and air, all sheet metal ducting run in the basement parallel the main beam and I believe are original- however here's my (negative) observations so far:

    Ducting:
    1) The basement already has low ceilings at 7 feet. The HVAC ducts run down the middle of the basement ceiling and underneath that area is 6' 3".

    2) The house has reverse flow venting- as in, in most areas the returns are on the exterior walls (uninsulated) and the supply are on the interior walls. The kitchen and bathroom have supply on the wall though. Makes no sense to me why it was done this way originally. I also lost two supply ducts when I had a foyer wall removed, so that area is constantly cold especially next to the front door. When the heater turns off, it seems like it gets cold quick.

    3) There are only 2 (one on the furnace/AC itself) supplies on the basement in the ceiling and ZERO returns except the furnace itself. There's a bathroom in the basement that has no ventilation at all. Thus, it's always cold down there.

    4) Minor issue but the existing grilles are somewhat noisy- (when I remove them it's quiet), which brings me to:

    5) The ducts are an odd size which I read is common for an older house, like 5x8 so it's almost impossible to find grilles for the vents. Which ties along with this- because of their off size, they are placed low on walls, and not the floors, so I have to use them with this ugly baseboard trim.

    Furnace:

    The furnace and water heater currently vents out a masonry chimney in the middle of the house. Since the house is small, it's taking up valuable room in the kitchen on the floor above and in the basement.

    To address these issues:

    Furnace:
    If I can move the furnace, I can get rid of the chimney, it will allow me to put in more counter space or a wall oven in place. I have a closet I believe I can have run vent pipe up to vent out the roof, it'll just have to be enclosed. I'd also would shrink the utility area and have more space to use as a basement. Which brings me to:

    Ducts:
    1) Since the furnace will be moved to a corner, having the Supply and return ducting run down one side of the basement wall (without basement windows) instead of the center as you see in most homes. This way, a soffit or wall can be built, I won't lose the vertical space, instead horizontal space which I have much more of. I have consulted one HVAC company so far and they've said the supply and return ducts can be run in a vertical orientation along the side wall. One place tells me 8" high ducting is standard- but are there any "wide and low" ducts?

    2) While this is done change the flow to be "correct" with the supply at the exterior walls (I'd specify floor vents) and return in the interior walls. I was told having floor vents would be best as the air will rise up and it "washes" the exterior wall, so this would address the cold feeling when the heat turns off syndrome.

    For the basement have the the proper supplies and returns, supplies down low to allow the heat to rise.

    3) The proper load calculations and sizing calculations should be done of the ducts.

    4) To move the furnace, a professional will have to capture, extend and recharge the line for the condenser, size and run the B-vent etc.

    I've talked to one HVAC company so far and they think I can keep the existing furnace. But they'd "plan for putting in a high efficiency furnace" when the 80% unit dies.

    I realize this is going to cost a good bit of money as it's basically installing a complete duct system AND paying for installation of the furnace as I'm moving it, but at least the house is small, and only 1 level (plus basement which is fully accessible) and I'll be using the existing furnace. But it will allow me to have better use of the basement without the low ducts in the way and allow more usable space in the kitchen above and basement and more even cooling/heating.

    Is this project I'm planning crazy or is this something that is actually done? I've searched around the internet and can't find too many people looking to move their ducts and furnaces. My other thought is to continue with the current setup and use space heaters or gas stoves/fireplaces for additional heat as needed.

    Anything else as a homeowner I should be aware of before I sign on the dotted line?

  2. #2
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,837
    To my eyes, it appears you have two issues. #1 is that the house is not well balanced and therefore uncomfortable. #2 is that you're trying to gain space in a couple of areas, the basement and the kitchen.

    On the face of the plan, it's quite feasible. Relocating the furnace and having a new duct system installed, if designed and installed properly, will result in even temperatures throughout.

    Moving the furnace to eliminate the chimney is relatively easy and should work out nicely. Don't hurt yourself removing the old chimney however.

    Now come the questions.

    Of prime concern to me are the dimensions of the home. The location of the furnace could be more critical if the home is exceptionally long. Furnaces have blowers with limitations and even the best variable speed models will run out of push if they're trying to move the air over very long distances. So the length of the house from end to end is a concern. I generally don't like to run ducts longer than 50-feet. So if your house is 75-feet in the longest dimension, I'd want to put the furnace somewhere in the middle and be blowing less than 50-feet in each direction.

    The depth of the home is the other consideration. When installing a main trunk right at the front (or rear) wall of the home, the branch run to the front supplies is measured in inches, while the runs to the back of the house is measured in 10-foot increments. It can get very tricky to get a well balanced system with such an imbalanced trunk. I'm not saying it can't be done but it takes a lot of attention to detail in the design and sometimes can be a daunting task to get it right when there are space considerations. It is for this reason that most duct systems occupy the center of the home and normally run parallel with the main girt or carrying timber in the house.

    In summary, as long as the house dimensions are not too big, most of it sounds okay. I'd put some reservations, however, on moving the trunk to one extreme wall.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  3. #3
    Join Date
    Feb 2004
    Location
    chicago suburbs
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    4,422
    you've moved this to the right forum...CFOT has a lot of "know it all" idiots.

    these guys here know the business.

    fill out your profile

    use this................ http://icemeister.net/aop_map.html
    FILL OUT YOUR PROFILE!!

  4. #4
    Join Date
    Feb 2012
    Location
    Maryland
    Posts
    14
    Hey Tinner.. Nice to see you! Glad I found this forum been reading it all night, especially the hall of shame part. No I def won't be DIY on this :lol: Did give it a thought but too much involved (can I say that in here?), too much can go wrong.

    I've gotta put some thought into this, you're right these guys here are great! Yourself included. I'm gonna type a reply to skippedover but need to do some drawings first.

  5. #5
    Join Date
    Feb 2012
    Location
    Maryland
    Posts
    14
    Skippedover thanks for the reply, quite informative. To answer your questions:

    Yes you see correctly of my 2 issues, the chimney taking up space and the uneven heating. The house dimensions are 38' x 26'. Currently the ducting runs down the middle parallel to the main beam. The 26' dimension would be tricky with the 10 foot increments, something I've never thought about.

    Another thing I'm kind of kicking myself about is I had the chimney rebuilt only 2 years ago. At the time I was up on the roof putting in a TV antenna and found the chimney disassembled with my bare hands At the time I wasn't thinking about reventing the furnace, but looking back, it was a perfect opportunity. If I do this I've effectively flushed a "good amount of money" down the drain for a new chimney

    If I were to keep the position of the furnace- should I bother with getting the ducts reversed? Not sure why in the old days the supply was in the interior walls and the returns were in the outside. At the very least I'd like to get some additional registers put in in the living room to even out the temperatures.

    To summarize, seems like I'm down to 3 options:
    1) Go all out, get the furnace moved, new B-vent AND new ducting run down the side wall. Including basement registers.

    Advantages- head room in basement, maximize space in kitchen and basement, "correct" reverse flow. More even heating/cooling, esp in basement. Since it's a parallel system to the existing ducts, existing system will still work while work is being done.

    Disadvantages- cost, it will be the most expensive option. Possibility that back half of house may not condition properly due to uneven load.

    2) Use existing ducting, but get new supply vents put in for living room and parts of the basement. Perhaps get the flow reversed.
    Advantage: cheaper than new ducts.
    Disadvantage: Ducts will still hang low in the ceiling, can't get rid of chimney.

    3) Do nothing. Keep the system as is. Use space heaters for living room and get a gas stove/fireplace for the basement.

    Advantage: Cheapest option.
    Disadvantage: Solves none of the original problems.

  6. #6
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    Feb 2004
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    chicago suburbs
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    By tinner_73 at 2010-07-15
    FILL OUT YOUR PROFILE!!

  7. #7
    Join Date
    Feb 2012
    Location
    Maryland
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    14
    I'll take some pictures this weekend

  8. #8
    Join Date
    Jul 2004
    Location
    Charleston, SC
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    930
    As it was explained to me some years ago, the returns were put on the perimeter in a heating dominant environment so the furnace would draw the warm air toward the heating load, not from the heating load to the center. Because the perimeter walls and windows are the largest heat loss area, the ducts were most likely laid out to keep the coldest air closest to a return. As long as all of the duct runs are in good condition and adequately sized, I would probably leave them.
    "Customer Service" is not a department, it's an attitude!
    ???

  9. #9
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    68,069
    Quote Originally Posted by cartercrew View Post
    As it was explained to me some years ago, the returns were put on the perimeter in a heating dominant environment so the furnace would draw the warm air toward the heating load, not from the heating load to the center. Because the perimeter walls and windows are the largest heat loss area, the ducts were most likely laid out to keep the coldest air closest to a return. As long as all of the duct runs are in good condition and adequately sized, I would probably leave them.
    Its a poor set up like that. My place is like that. Can make you very uncomfortable, when the blower shuts off.
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  10. #10
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    Feb 2012
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    Quote Originally Posted by beenthere View Post
    Its a poor set up like that. My place is like that. Can make you very uncomfortable, when the blower shuts off.
    Beenthere- I'm curious if your house has a poor setup and you're involved in the HVAC trade, would you not correct redo it?

  11. #11
    Join Date
    Sep 2007
    Location
    Boise, ID
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    4,270
    Quote Originally Posted by cartercrew View Post
    As it was explained to me some years ago, the returns were put on the perimeter in a heating dominant environment so the furnace would draw the warm air toward the heating load, not from the heating load to the center. Because the perimeter walls and windows are the largest heat loss area, the ducts were most likely laid out to keep the coldest air closest to a return. As long as all of the duct runs are in good condition and adequately sized, I would probably leave them.
    Not being disrespectful, but I don't buy that. You want to wash your windows with heated air, it cut's down on drafts. Allot of Hospitals etc. have vav boxes or convectors right bellow the window. A home is really no different. I think Kruegar is the the one that has an auto change over grill that blows air towards the window in heating, and inwards into the building during cooling....pretty cool technology.

    As long as you have the right amount of air, proper air distribution methods so you are mixing the room properly it's not going to matter where the return is because your room is at an even temperature....when properly mixed.
    If a nation expects to be ignorant and free, in a state of civilization, it expects what will never be. (Thomas Jefferson 1816)

  12. #12
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    Quote Originally Posted by Ed Ww View Post
    Beenthere- I'm curious if your house has a poor setup and you're involved in the HVAC trade, would you not correct redo it?

    Like I really feel like working more when I come home.

    So I cheated, and made an adjustment to the supply registers that works ok for me.

    If I install the heat pump this year, then I'll almost have to change the supply and returns.
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  13. #13
    Join Date
    Feb 2012
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    Quote Originally Posted by beenthere View Post
    Like I really feel like working more when I come home.

    So I cheated, and made an adjustment to the supply registers that works ok for me.

    If I install the heat pump this year, then I'll almost have to change the supply and returns.
    This reminds me of when I went to the mechanics long ago, and I saw the guy working on my car drive away in this POS that made all this noise. Or, when the Safelite glass repair guy came and the windshield was cracked on HIS truck

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