HVAC setup question

Discussion in 'Home Theater Projects' started by ChristW, Dec 3, 2003.

  1. ChristW

    ChristW Agent

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    Ok, we called 4 HVAC people to come and give us estimates today. Two were no-shows, 1 has come, and one is supposed to come in a few hours. Seems that the HVAC people in the Twin Cities don't care about business. Anyway, here's a diagram of our basement --

    http://www.fezam.com/basement2.gif

    The theater will be in the 11.5x12' area, a general area will be above that, and the office will be separately framed out just above the stairs. The equipment closet is in the little 4.5x area on the bottom of the picture (also has a sump pump in it...)

    Anyway, we're fixing up our basement to be a general HT area (nothing elaborate, just a place to watch movies), as well as putting in a small office. I've been told by a few people that the heat ducts should go to the floor and the returns should be near the ceiling, to make sure that the floors stay warm.

    The guy who came to give an estimate said that putting ducts in the floor isn't practical and that "all basements" (gotta love generalizations) have heating in the ceiling. He wants to put in three "diffusers" in the basement ceilings, one in the middle of the theater area, one in the middle of the general area and one in the office. He then wants to put three returns, one in the middle of the left wall (he said it'd be a double), one in the office, and then one in the equipment closet (at the bottom of hte picture in the 4.5' area) to help get heat out of there. I asked a couple times about putting the heat ducts in the floor, but he kept saying it wasn't practical so it's obvious they won't be doing that.

    First, I've never had anyone tell me to put the heating in the ceiling... That seems a bit odd to me. Doing what he's saying, wouldn't that leave most of the right hand side of the theater area (where the screen is) without much airflow, since the heat comes out of hte middle, then gets sucked up to the left.

    Second, will it help putting a return in the equipment closet, or am I just wasting my money?

    The cost comes in at $600, which seems reasonable to me. But I'm just not sold on putting a vent of some sort in the ceiling... Seems like it'd look distracting and be annoying. Anyone have any suggestions? Thanks all!
    CW
     
  2. CurtP

    CurtP Extra

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    I've never seen ducting in a basement floor -- I always figured it was because it's not a practical installation since the floors are concrete.

    When we had the HVAC guys out to replace our system, he told us the best way to heat/cool a room was to place the vents in the ceiling, within 18" of the outside walls, and the cold air returns low in the walls. I thought it sounded funny for heat, but when my dad had his house HVAC system redesigned, that's exactly the way they did his as well. My dad and I don't live in the same region (I'm in Southern Virginia, he's in Central Illinois, and our HVAC sytems are completely different (mine is a heat pump, his is LP gas). However, this wasn't for a basement in either situation, but the way the HVAC contractor made it sound, it was universal.
     
  3. Frank Zimkas

    Frank Zimkas Supporting Actor

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    Curt & Chris,
    Generally the main supply and return trunk lines are overhead in a basement. Therefore adding supply ducts in the ceiling between the floor joists allows for better air flow, which maintains proper system performance. Trying to re-invent the wheel and running supply ducts from the supply trunk down to the floor and then across the room adds a lot of lengthand 90deg. elbows, which which will cause poor air flow. Having a return low in a basement won't hurt anything at all, provided that the return is not too large, an oversized return in a basement will allow more air to be taken from the basement than from the upper level. Make sure the contractor you choose does not place the return too close to the furnace itself. Doing so will make the blower noise quite loud.

    Chris, Where is your mechanical room located? I couldn't tell from your drawing.
     
  4. ChristW

    ChristW Agent

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    Thanks for the reply -- I guess I was worrying for nothing...

    My furnace is actually where the stroage area is shown in the upper right hand corner. Both contractors recomended putting the return vent either on the wall opposite the stairs or on the wall just around the corner from there.

    The first contractor said that putting a return vent in the closet would be a good idea. The second guy said that he would just leave the ceiling unfinished and the heat should be able to get out there way (maybe with the help of a fan). I'm starting to think that it might be a good idea to put a vent there too though.

    Regarding the return vent in the theater area, you mentioned that if it's too close to the furnace, the fan noise will be loud. Is that why people suggest putting bends in the ducts? Is that just for return ducts, and is that something I should ask for?

    Thanks for the helpful info!
    CW
     
  5. Frank Zimkas

    Frank Zimkas Supporting Actor

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    Chris, Bends in the return duct will cut down on the noise. The same is true for the supply ducts, but I don't recommend it. Every bend in the supply ducts will decrease the airflow in that run of duct. Keep in mind that I look at a system from an HVAC guy's standpoint. I'm more concerned about the overall performance of the system than I am about the sound level in a theater. Using insulated flex-duct (when properly installed)can reduce some of the noise from the air passing thru it. You could also specify flex-duct for the return as well.

    Your supply grills should be located near the outside walls, preferably near any windows/doors (that's where the greatest heat loss is).

    Placing the return grill at floor level will allow the cold air at floor level to be pulled back to the furnace.

    Consider adding a Heating/Cooling thermostat if you don't already have one. It will have a fan switch that will allow for continious fan operation to circulate all of the air in your home. Doing so will eliminate any hot or cold spots (Stratification).
     

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