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Cold air returns in ceiling? 2 stage vs modulating for a more efficent forced air

wiscoguy | Posted in General Questions on

My heating guy is telling me he thinks the best way for the cathedral area to circulate air is through the ceiling however I will have 2ft if blown in to get to r60. So I know forced air isn’t the favorite heat around here but if you are using it does it make more sense to put returns in the ceiling on a cathedral. I do t think it’s necessary because I will have a couple ceiling fans moving air as well as a couple air return on the upper part of the wall. I just wanted to ask here because I’ve gotten some good info in the past. 

Also along that same line of questioning since I’m going with force air my heating guy says the most efficient would be a fully modulating unit because it can cycle down to 8000 btu but  cycle up to 60000 it should never be used more than needed vs a 2 stage hopefully someone has an opinion on this as well.

Thanks, Tom

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  1. paul_wiedefeld | | #1

    Nothing wrong with forced air - it’s by far the most common set up in the US.
    In terms of efficiency- no gas furnace is efficient when compared to a heat pump, that’s pure gas marketing fluff. Consider a hybrid furnace/heat pump system - the heat pump will handle the majority of the heating, more efficiently. The furnace can be there for the coldest temperatures and backup.

    Just curious, which furnace modulates down to 8k Btu? While a modulating furnace will match loads better (ie more comfortable), I’m not aware that they’re any more efficient.

  2. Expert Member
    BILL WICHERS | | #2

    I would not run ductwork in a cathedral ceiling. Is there a way you can locate the returns up high on interior walls instead? Keep the ductwork enclosed in the interior wall, or build a vertical chase?

    You want to avoid running any ductwork in any attic spaces as much as you possibly can. There are multiple reasons for this. Cathedral ceilings make everthing more critical too. Your HVAC guy is correct that having the returns up high can be beneficial, but if you put them up on a wall near the peak of the cathedral ceiling, you get nearly the same benefit as if they were in the ceiling itself. Convection currents will naturally carry warm air along the sloped cathedral ceiling to get that air near the returns.


    1. wiscoguy | | #3

      Thanks this is what I was leaning towards as well.

  3. Expert Member
    Akos | | #4

    Definitely not down with forced air heating here. The general beef tends to be with systems are way oversized which can create comfort issues. A well sized fully modulating heating system (fuel burner or heat pump) is a fantastic heat source. Cold climate heat pumps work incredibly well and can fully heat a place even bellow -15F without any backup.

    On that note, judging from the R60 roof, 60000 BTU well feels oversized for most well sealed and insulated new construction builds. Make sure that is correct.

    1. wiscoguy | | #5

      I understand the not liking forced air but all quotes I revived for mini splits and other forms of heat were unfortunately not affordable. So with that in mind I’m trying to do the best I can with forced air. It’s either a two stage or a fully modulating that I can afford.

      That’s what I thought as well it was calc out by a design firm based on my sq ft and windows wall insulation etc.

      This is why I thought a modulating furnace that can run down as low as possible may be the best bet.

      1. paul_wiedefeld | | #6

        You received ducted heat pump quotes (NOT ductless mini splits)? They should have comparable to a modulating furnace and you get AC, better sizing and higher efficiency.

      2. Expert Member
        Akos | | #7

        A budget cold climate heat pump is at most 2x the cost of a budget AC unit. You take out the cost of the fuel bruner, cost of running gas lines and cost of vent pipes, you are pretty much break even on cost. Much less labor as well.

        I would not try to quote mini splits as these tend to be silly cost as you have found.

        Stick to heat pump brands your installer is familiar with. Carrier has some decent in house cold climate units and some rebadged Midea ones. Either is a great choice for a new build.

        Heck, you can even get one form a box store for under $4k. Search for MrCool universal.

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