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Will AC rob heat

Post in 'DIY and General non-hearth advice' started by Downeaster, Jul 11, 2008.

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  1. Downeaster

    Downeaster New Member

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    I am talking with a HVAC contractor about having AC installed in my home. It is a ranch style house and my pellet stove is on the northeast wall. The contractor is talking about installing duct work through the attic so as to be able to cool the whole house, I initially was looking at a ductlesss unit placed in the center of the house and letting the cool go where it may. My question is, as we all know heat rises, will the duct work suck the heat out of the room nullifying the benefit of the pellet stove and making the rooms furthest away colder than I want them to be?

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  2. begreen

    begreen Mooderator Staff Member

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    I wouldn't expect it to have a dramatic effect as long as the workmanship is good. The ducts should all be well insulated (at least R8) and every joint sealed. Every hole in the ceiling is a potential source of cold air infiltration in the winter, so they should be careful insulating and sealing the register boots as well. You may want to block off the return air grille in the winter if you feel cold air coming from it.

    FWIW, some of the mini-splits are really nice and especially quiet. But, depending on the size of the place, it often takes a couple units or a window unit in the bedroom at opposite sides of the house to do the job.
  3. fossil

    fossil Accidental Moderator Staff Member

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    BG, I know what a mini-split is in terms of both champagne and firewood, but in the context of A/C, what sort of unit is it you're referring to? Rick
  4. begreen

    begreen Mooderator Staff Member

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  5. fossil

    fossil Accidental Moderator Staff Member

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    Pretty cool looking little units (so to speak). Thanks, BG. Rick
  6. Lumber-Jack

    Lumber-Jack Minister of Fire

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    I was looking at a ductless heat pump system for our house when we renovated it, I ended up going with a full duct system and here is why;
    First of all because I could,,,,, that is an important point, if you can't feasibly install ducts because you don't have attic or crawl space access them you pretty much have to go with a ductless system.
    Second; the duct system gave me a heating (and cooling) duct in every room, the ductless would have only been in 3 rooms.
    Third reason; was because I much prefer having all the air circulating and recycling though the whole house, upstairs, main floor and even the crawl space to some degree. If I had gone with a ductless system, my crawl space would likely be a cold, musty smelling place because it wouldn't get any air circulation, but with the ducts and the furnace down there, there is enough circulation to keep it fresh and dry down there, no musty smell at all.
    Forth reason; it was actually a bit cheaper to go with the full duct system as opposed to a 3 unit ductless system although price was not the deciding factor by any means
    A fifth reason; which relates back to reason number three is with heating with a wood stove I like to leave the fan on low in the furnace so it circulates the air around and helps balance the temperature through out the house, my only regret was that I was not able to install a cold air return in the room with the wood stove, that would have helped even more.

    BTW, we also had to run some of the ducts in an attic space to reach one of the rooms (the wood stove room actually) and although the heating guy insulated the ducting, we put more insulation over them again by wrapping the ducting with bats of insulation and wrapping it all again with lumber tarp type material. Had the ducts been installed right on top of the rafters one could just pile more insulation over top the ducting.
  7. madison

    madison Minister of Fire

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    My opinion/experience is yes. There is significant heat loss to the AC duct in your ceiling. Even with decent insulated ducts.

    This is our third yr in this home, the first winter I felt cold air running down an interior wall, traced it to the A/C ducts, after checking closing all the ducts, the draft was not as bad. But I ended up cutting 12" squares of insulation and each fall I remove the registers that I can easily reach, and plug them up with the insulation. I also fashioned a large piece of cardboard with insulation to cover the large inlet register in the ceiling. This cut the draft quite a bit and reduced the snow melt on the roof in the sections of the attic where the A/C ducts were located. Takes about an hour or two with an electric screwdriver to get the job done. I also laid R -30 on top of the ductwork in the attic.

    A HVAC person suggested that you could wrap the A/C filter with plastic wrap to reduce the passive recirculation thru the ducting during the winter. I did not try method yet.
  8. fossil

    fossil Accidental Moderator Staff Member

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    This thread's more than a year old. No idea why it was dredged up. In any case, I'm moving it to the DIY forum. Rick
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