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  1. #1

    Heat Circulation

    I already put this thread in the fireplace section but I thought I'd also try here since it kind of pertains to both topics:

    I wonder if I could pick your brains? I'm a contractor/carpenter in Ma. I've been presented with a question from a HO. They are interested in moving air from the 1st floor (radiant heat source) to the second. Tried fans with limited success. I actually have a similar situation in my own home.

    I've thought about this for some time, talked to many, and the best I could come up with is an in-line fan in a ceiling joist bay with a vent above (second flr floor vent) and a register below (1st flr ceiling). Probably 6" vent. Any concerns, ideas? Has anyone done this? Do you think it will move enough air to make it worth it? Ant fan products you would recommend/stay away from?

    I'd also like to hide/blend the ceiling register. Empty recess can; speaker trim?

    I've yet to talk to anyone who has tried to solve this problem. I find it hard to believe due to the recent popularity of wood stoves/high price of oil. I'd appreciate any feedback. Thanks in advance.

    -John

  2. #2
    Join Date
    Feb 2008
    Location
    Dallas & Longview, TX
    Posts
    629
    How many sq' of upstairs are you trying to heat? You would have to move an awful lot of CFM to heat more than a small room with what you're talking about.

  3. #3
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
    Posts
    1,582
    with a grate in the floor to allow heat to rise up thru to the room above you will get mininum heat rise or natural convection, but you may also want to add another floor grate on the opposite end of the room to allow for cold air to fall down to the downstairs for the cold air returns to pull that air back thru the return on the furnace. Are there no partition walls to pull and ducting up thru and into the room in question even a 4" duct or maybe a 6" oval duct ? What about ducting up thru the exterior wall of the home to the room upstairs by way of the exterior of the house by opening the wall from outside. I did this in my home and have not had any problems resheated the wall cavities using 1/2" foam bd and then another 1/2" over the entire exterior wall and resided. Like they say there's more than one way to skin a cat

  4. #4
    Daltex,

    It's only about 400 sqft (two small bedrooms and a hall) and I'd be happy with an increase of 5-8 degrees. This is to supplement a forced hot water system. The first floor of this home gets to be in the mid 80's when the stove is rippin'. I'd like to get some of that warm air up to the 2nd flr and, as a result, also cool down the 1st flr. Any ideas?

  5. #5
    Dan,
    I've thought of the direct/straight vent option. I'd like to avoid it if I can due to sound travel. Also, I'll have to talk to my inspector to see if this is a fire code violation in MA (direct path of travel between floors for fire).

    The duct through partition/exterior walls may work. Seems like more work than an inline fan (especially the exterior walls) but if I can't come up with a better idea that's probably what I'll do. Thanks for the input.

  6. #6
    Dan,
    Does your exterior duct make a noticable difference on the second flr? Is there a fan in the duct to help push the air?

  7. #7
    Join Date
    Feb 2008
    Location
    Dallas & Longview, TX
    Posts
    629
    Quote Originally Posted by libertybuild View Post
    Daltex,

    It's only about 400 sqft (two small bedrooms and a hall) and I'd be happy with an increase of 5-8 degrees. This is to supplement a forced hot water system. The first floor of this home gets to be in the mid 80's when the stove is rippin'. I'd like to get some of that warm air up to the 2nd flr and, as a result, also cool down the 1st flr. Any ideas?
    I wish I knew more to assist you better. Without the existing heat it would need a guestimate of 500+ CFM to circulate the heat. Deduct the existing and I don't know. The heat already pressurizes the upstairs so instead of adding more pressure maybe you should push the cold down and let the stairwell let the heat rise faster? In other words the opposite of what you are talking about as the inline would blow air off the floor upstairs and push it downstairs. The downstairs heat would rise to keep the pressure differential even.

    Sounds way over my head.

  8. #8
    Join Date
    Feb 2003
    Posts
    1,996

    Is there any kind of closet

    on the first floor that could be used as a return plenum. As said, with all the
    vents in the ceiling and the starwell allowing hot air to rise, cool air must be given a place to return.

  9. #9
    Daltex,
    I think you are right. The upstairs is pressurized and the warm air from the first floor can not get up the stairwell. Maybe I should be pushing the air down and not up. What is the best way to do so? I guess that's the question.

    Johnsp,
    No, no closet on the first floor that would work for the second. Good idea though.

    This is kind of what I was talking about in my original thread. This seems to me like it would be a common problem. You guys (HVAC techs) are my last hope. I can't believe that there isn't a solution that hasn't been implemented, tested and accepted. Keep the ideas coming. Maybe we can come up with one.

  10. #10
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    go look how an old 'octpus' furnace was installed -
    -- LARGE grates in the floors -- return & supply
    -- except on the inside walls so as not to block the whole bsmt!
    -- because of the LARGE pipes = 18 sply, 30+ return.

    in my youngest daughter's house in Ft wayne IN, ca 1914:
    -- the return grates of 0.75^ oak having 2x3 openings
    -- supply grates are heavy metal -- with scrolls
    both in the floor.

    yes, such does present a fire transit --
    -- but not as much as an open stairwell!

    my oldest just uses a box fan to push hot air up the stairway from the 1st floor from the pellet stove. -- 4y now.
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  11. #11
    Join Date
    Feb 2003
    Posts
    1,996

    if you had an A/C duct system

    running the fans would help move air around. Maybe you could use an interior non bearing wall stud partition as a return plenum. Issue here is there's usually headers and the subfloor between floors blocking flow. Fire codes usually don't like this stuff as it would allow fire to travel between floors faster. Building a closet or false wall would give you a plenum where the return grills could be placed low on the wall to deliver cooler air back to the first floor.

  12. #12
    Cem,
    As mentioned above, I'd like to avoid the straight vent/grate method if I can. HO is worried about sound travel and I don't think my old lady would be too happy about it in our house either. I've tried every fan set-up I can think of in my house and it doesn't quite push the warm air up the stairs. Second flr is already pressurized and existing air has no place to go.

    Johnsp,
    Yeah, this is a new home. No balloon frame. I'd have to cut plates in bearing walls to use the wall frame as a plenum. Also, with this new "open floor plan" stuff, there aren't many petition walls to use. This kind of eliminates any options for using interior walls which is why I was wondering if any of you have ever seen/heard about a system that would work in a ceiling joist bay?

  13. #13
    Join Date
    Dec 2007
    Location
    Cedar Grove, Wi-Sheboygan
    Posts
    1,582
    Quote Originally Posted by libertybuild View Post
    Dan,
    Does your exterior duct make a noticable difference on the second flr? Is there a fan in the duct to help push the air?
    Yes the ducting running on the exterior walls works well, I have a very old farm house and what I did was replaced the electric base bd heating with forced air up stairs and as I mentioned used the exterior walls and ducted up them since I was in the midst of residing my house anyways so it was fairly easy to do. For a cold air return I used the chimney which became abandoned when I replaced my hotwater tank to a direct power vent, I capped off the chimmney in the attic, knocked a hole in the base of the chimmney 8" X 10" just above the floor level and then did the same in the basment and connected to my return drop with 8" rd ducting and this set-up allow me to keep my upstairs within 1 degree of my main floor. As for any sound problem with sound traveling thru the ducting there is no such problems, I sheated over the exterior wall cavity using 1/2" foam bd and then another sheating of 1/2" foam bd. so where the wall cavity was there's 1" of foam bd for insulation and should keep the duct from accumulating any type of condensation during the cooling months. As for putting floor grates in your floor I never thought about the venting problem the house will have if or when there would be a fire in the house, being a former fire fighter I should have noted this but things happen, To eliminate the excessive pressure up stairs which would allow heated air to travel up thru the stair well you might just have to build a return in the corner of the room that would be out of the way of the main floor plan but also centrally located to pull the cold air from the majority of the second floor at the sametime. How is the stairwell build in the home ? Is the stairwell enclosed on the top floor or is the stiarwell opened up once you enter the second floor ? If the stairwell is enclosed with walls you could possilby use those wall cavities as cold air returns and wither run them just to the first floor or if your able connect them directly to the return in the basement. Can you supply a floor plan of the home in question, it would be easier to see what barriers you have to work with as for me it's hard to visulize just what your having to deal with.

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