Request for solution to the hot second floor, cold basement challenge.

Discussion in 'HVAC' started by Hondo123, May 29, 2012.

  1. May 29, 2012 #1

    Hondo123

    Hondo123

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    I have a cape cod built in '67 with central air and aluminum forced air ducting. It appears the previous homeowner added some insulation to the roof. However in the summer, the second floor continues to get warm and stuffy even with all the registers wide open, while our basement is morgue cold. Our intake ducting near the fan unit in the basement does have a small louvered vent that I assume is there to draw in cold air into the system when it is blowing, but this hasn't made much of a difference to cooling the house to the best of my knowledge.

    I'm very curious if there's a "better way" to move all that good cool air that has sunk into my basement to the top floor where it can be put to good use. I have often wondered if perhaps there was some sort of solar air movement system I could use to draw that cold air to second floor, or perhaps some addiitional ducting that could be installed in tandem with a standard electric recirc fan. I'm not wild about having a fan running all the time, which I why I wondered about the solar unit, which could run continuously during the day "off the grid".

    Anyway, very interested in potential solutions to this challenge, even if they do not incorporate some of my initial ideas.
     
  2. May 30, 2012 #2

    joechuckg

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    Do you only have one thermostat either upstairs or down. If so you might want to look into a zoning system where a thermostat would be added so you would have both floors controlled by dampers in the ducts. Can be kinda expensive but it would solve your problem
     
  3. May 30, 2012 #3

    Hondo123

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    A second themostat will do nothing more than cause the A/C to run continuously as it tries to cool the top floor. The cooling is not a problem. The problem is I have a large pool of over-cool air sitting in my basement (probably "ponding" from the rest of the house) and a hot second floor (or call it third if you count the basement as a floor). Just need to get all that good cool air moved to where it's needed. A dual zone system would probably just make the basement even colder than it is already.

    Any other ideas? Am I the only homeowner with this kind of problem?
     
  4. May 31, 2012 #4

    Daddytron

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    Cold air will always have a tendency to settle as the warm air pushes its way up... duct booster fans are a simple (but noisy) solution. If you have means of installing a door on the basement at the top of the stairs and keep it closed, this would be an energy efficient solution. unfortunately... all the windows on the main floor and upstairs allow all that free heat from the sun into the house, and keeping the blinds closed makes a house feel like a dungeon. In my house, i keep a fan running at the base of the stairs, to push the cold air around, but once it hits around 80 outside, my AC runs non-stop and can't keep up. If you find a solution, please let us know
     
  5. May 31, 2012 #5

    Hondo123

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    A good thought, however we do have a door at the top of the stairs, and we do keep it closed nearly all the time. Didn't know about duct booster fans, but might consider it. We have Energy Star rated windows where the sum comes in on the two large ground floor bay windows, so sunlight heat is not so big an issue on the main and upper floor (which has only one window facing the sun throughout the day). In fact, most of the upper floor roof is shaded by a large maple tree in our front yard.

    You would think "they" could come up with a system that would provide even distribution of heating or cooling throughout the entire living space. It's a no-brainer that heat rises, and cool air falls. I wonder why home systems are not designed to maximize distritrubtion throughout the "thermal container" in a multi-floor home. This just seems to be good design philosophy, opposed to just installing some ducting and a heating/cooling source.

    I may ultimately need to come up with my own solution, perhaps additional ducting that chimney's straight up through the center of the house bypassing the middle floor with some sort of reversible fan attached to a thermostat that will move somewhat large volumes of air from basement to top floor, and reverse in the winter.

    Anyone else with thoughts on this? I know my problem can not be unique.
     
  6. Jul 16, 2012 #6

    Daddytron

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    We just had our once-a-year heat wave... temperatures in the high 80's to low 100's. and for the first week of this, my a/c was running constantly, trying to get the house to 74. During the second week of it (average daytime high of 91 with a 85% humidity). I flipped the switch on my thermostat to run the furnace fan constantly, the a/c would actually have a break for about 15 minutes every 10 minutes of running, and I was able to get my house down to 70. The basement is probably only about 5 degrees cooler than the main floor now. Maybe this will work for you?
     
  7. Jul 16, 2012 #7

    CallMeVilla

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    You need to have the AC system checked for leaks. This sounds like a problem of insufficient cold air distribution to the top floor and a major leak in or near the basement. An air flow meter can quickly identify the rates on various floors. Bad joints, improper returns, holes cut by prior owners . . . all can be the problem.

    Good luck living in the basement to stay cool. :D
     
  8. Jul 19, 2012 #8

    EdB868

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    How many square feet and how many supply registers are on the upper floor?

    It's possible there are not enough supply air registers.

    Veteran HVAC professional
    www.needtoknowit.org/HVAC
     
  9. Jul 20, 2012 #9

    CallMeVilla

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    Stay on him EdB . . . He needs your help! ;)
     
  10. Jul 21, 2012 #10

    EdB868

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    If you live in the northern band of the country,
    chances are the duct system was designed for heating.

    Cooling requires more air flow than heating -
    I suspect there is not enough air going to the upper rooms.

    You should have two supply registers in each of the
    upstairs rooms.

    One possible solution (not that easy, but possible) is
    to run a 9" duct through a 1st floor closet to an area
    behind the 2nd floor knee wall, then install a 9" x 6"
    tee and run 6" duct to each room.

    Also, make sure the ducts in the basement are sealed
    with duct mastic.

    You will most likely have to turn down the damper
    during the winter, otherwise it will get too warm.

    If that is not practical, look into ductless split system.

    37 year HVAC professional
    www.needtoknowit.org/HVAC
     
  11. Jul 22, 2012 #11

    lloyd

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    Open up return to basement, tack on a filter, flip thermostat fan switch to "on". You can partial block other returns to force the system to draw in basement air.
     
    Last edited: Jul 22, 2012
  12. Jul 22, 2012 #12

    CallMeVilla

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    Hey Lloyd, that is a creative and possible work-around to the crisis . . . but it will not solve his problem long term. If there are chronic leaks in his ducting, the hot upper floor problem will continue. He needs to find the CAUSE for the symptoms and deal with that directly. :D
     
  13. Jul 23, 2012 #13

    EdB868

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    Seal all the ducts (supplies and returns) with mastic.

    If there is a 1st floor closet that lines up with an area behind the 2nd floor knee wall, install a 9" round duct through the closet.

    After the duct reaches the 2nd floor, install a 9" x 6" tee, then attach (2) 6" ducts to the tee.

    Install register boots and wall registers to distribute the air to the 2nd floor rooms.

    Be sure to install a volume damper on the 9" run near the trunk duct in the basement to decrease air flow during the winter months.

    37 year veteran HVAC professional
    http://www.needtoknowit.org/HVAC
     
  14. Jul 23, 2012 #14

    Hondo123

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    I would agree that the air going to the upper rooms is not what it should be, and one room does in fact have two registers, but again, the problem is not a hot top floor - it's a hot top floor AND a cold basement. I think in terms of overall BTU, the total home is getting enough cold air - it's just not getting it in the right places, or, perhaps the basement in this home is naturally cool, and I would like to capitalize on that by moving it where it's needed. So the challenge is to figure a way to move the cold air.

    I have been scoping potential areas where it might be possible to cut some holes and run some ductwork from an intake on the floor of the basement to a T on the top floor. It would require a fan and a themostat I figure. Do you know if there are any temperature controlled "fan" systems that would activate once a certain temperature would be reached.

    I'm kinda surprised home HVAC systems have not been designed to circulate air "whole house", given the obvious tendency for cool air to settle to the lower floors. There must be millions of cool basements all across America that could be recirculating that cool air to other parts of the home. I'm surprised there's no ready solution out there.

    That might be a bit pricey.

    This is good information and helps me understand my options. I'm now dealing with a separate home problem concerning a carpenter who said he could install new interior doors in my home. These doors were not pre-hung. The doors were sent as a door, two side pieces for the frame, and a top piece. I needed seven door installed, and after he started on the third, I had him stop, wrote him a check, and wished him well. Not one of the frames was square, and I didn't see him using a level. And that was just for starters.

    Lloyd, I think you're on the right track, but I need a "set and forget" kind of solution, so can't run around resetting registers all the time. However interesting idea. As for checking for leaks, I should probably consider having the ducts checked. Since the home was built in '67, I don't think they bothered wrapping ducts, at least mine aren't, as far as I can tell.

    As an additional point of information, another consideration is that the home is a Cape Cod, and there is significant square footage of the "ceiling" of the upper rooms that has no crawl space, since it's part of the roof really. I have thought about tearing out wall board and then putting high R insulation in there to help insulate, but that may be overkill.

    Anyway, keep the ideas coming. I'll figure something out.
     
  15. Jul 23, 2012 #15

    nealtw

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    If the basement stays naturally cool, why not take it out of the loop and close all registers and returns there and close the door to the basement?

    You may have hit on somthing in the roof. Do you have soffet vent and roof vents on the or near the peak. In the area where the ceiling is the roof, is there a path for air flow between insulation and roof sheeting?
     
  16. Jul 24, 2012 #16

    Hondo123

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    The registers are closed, and the door stays shut. That was the first (and most obvious) solution I tried.

    Aside from mastic on the ductwork, is there anything to be gained by insulating the ductwork?

    Yes, I do have roof vents and a thermostat controlled fan to move the heat at the peak. The fan unit should probably be replaced, as it makes a little bit of racket when it's running. I think the frame where it is attached to the house has gotten a little loose over time, and the unit itself is probably old and ready for replacement. I don't know if anyone has a suggestion for a good replacement unit. The vent itself is fairly sizable - possibly 18 inches square.

    As for a path for air flow, I believe the answer to that question is, "No". In the winter when snow melts on the roof, you can sometimes make out where the studs are located under the roof. I will need to get the roof shingles done sometime in the near future and am wondering if there is something I can do to provide more insulation, or other options, such as an attic "heat thermal shield". We are also considering some of the new Dow solar roof tiles as well that can be applied almost like asphalt shingles, though these are black and might compound the warm third floor problem.

    Appreciate Bob's ducting information, and that may well end up being put to good use. That still leaves a thermostat controlled fan unit to move the air. I suppose they must be out there somewhere.
     
  17. Jul 24, 2012 #17

    nealtw

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    I don't know alot about these fans but I would think that they would just pull air from the nearist available source. If it is not set up correctly it could do more harm than good.
    What air would be going out the vents at the peak?
    Air the soffet vents open or are they blocked with insulation on the inside?
    Does the fan move alot of air or is the noise just the fan chopping the air because there isn't enough air to move?
    You said something about dropping drywall and insulating, I would add 2x4s to the rafters so you get more insulation and still have 1 1/2 " for air flow.
     
  18. Jul 26, 2012 #18

    Hondo123

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    Not as interesting as you may believe. Millions of houses have basements where cold air sinks, and that's where it stays. It seems the current solution is pretty Neanderthal - adjust vents or pump more cold air into the space. I'd like to use what I have more efficiently.

     
  19. Jul 29, 2012 #19

    CallMeVilla

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    So, Hondo, you have been given a remarkable amount of valuable advice. Have you actually DONE anything about this problem yet? Just askin' :D
     
  20. Jul 30, 2012 #20

    Hondo123

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    Not yet. If you expected me to "spring to action" and start cutting holes in my floor and ceiling, the answer is, "No".

    The most pressing problem in front of me at this moment is getting seven solid wood interior doors installed on the main floor. These are custom doors, so I needed a good finish carpenter to hang the doors. What I got instead was a framing carpenter with an overly high opinion of his skills. (What carpenter would hang a door leaving bent nails in the frame and ding marks around the jamb? Not a good one is the answer.) I unfortunately didn't catch this mess until he had started on door #4. I stopped him, wrote him a check, and told him to leave. Now I must pay another carpenter to fix this mess, and install the remaining doors. Fortunately, I've found one that specializes only in doors. The renovation budget is obviously going to take a hit as a result.

    Right now, the upstairs is not used except for guests, however we expect to move both kids into the bedrooms upstairs sometime soon, so this is a challenge I will need to deal with soon. At this point, I'm trying to determine "what's the solution" and "how much".
     

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