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Community and Q&A

Conditioning and venting a small cellar – Western NY

fitchplate | Posted in General Questions on

Gentlement, what do you advise?

Option 1 – Supply and return of conditioned air approach: Seal the cellar and exchange conditioned air a supply and return approach using 2 or more floor vents/registers between cellar and the main house envelope. Possibly use humidity controlled booster fan in a vent.

Option 2 – Supply only, positive pressure approach: Use one vent pathway only, for pushing conditioned air into the cellar (no exchange with the house). Humidity controlled in-line vent fan.

The cellar is heated by HW wall hung radiators and insulated to R30 above and below grade. Exterior entrance way only. Used as utility area for 40 gal pressure tank, water filtration, and host the plumbing and septic drain chase.

Zone 5 B and soemtiems 6 – Winter is not so much as issue as you know, but summer has its special humidity and condensation problems.

Thanks in advance

(PS and yes AJ, it is a “toxic” preserved wood foundation, but its sealed off from the interior space)

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  1. GBA Editor
    Martin Holladay | | #1

    I use the term "cellar" to refer to an old-fashioned low-ceiling basement with stone-and-mortar walls and a dirt floor.

    What about the area you are talking about? Is it a basement with a slab floor? Can you stand up in it? Will you ever use it as finished space?

    Or is it just a crawl space?

  2. fitchplate | | #2

    Martin ... it is small area (8 x 20 rectangle, 7' ceiling) preserved wood foundation, including the floor, 20 mil vapor-bulk water barrier encapsulated, below the conditioned space (separated by an insulated framed floor), heated, with insulated exterior door and stairs capped off with a bilco door. Built for weather protection and housing of under building plumbing and the well water entrance (the boiler is not in this space). It will never be used as routine part of living space but will be used for bulk storage of consumables and pantry type storage (i.e. preserves, etc). It could be used as a cold room but it is not intended to be humid enough for garden and orchard produce storage.

  3. GBA Editor
    Martin Holladay | | #3

    If I understand correctly, the basement is heated by hydronic radiators. I see no reason why you need to ventilate this basement.

  4. Expert Member
    Dana Dorsett | | #4

    Even as a storage space it's worth giving it at least some modest amount of ventilation, but it needn't be active ventilation, since any outgassing of either the construction materials or stored goods could stagnate at unhealthy levels. A couple of grates on opposite ends of the basement, located where there would be convective air transfer between the upstairs and the conditioned basement would probably be enough, even without a booster fan.

  5. fitchplate | | #5

    Thanks, Dana ... That seems like a simple, safe and cost effective solution.

    Martin ... yes, it is heated with a hydronic rad.

    With opensing to the above, there will be natural convection and air exchange that might also increase infiltration in winter. I would like to reduce infiltration in summer with postive pressure for with a humidity controlled in-line fan pushing conditioned air down..

  6. GBA Editor
    Martin Holladay | | #6

    Most well constructed basements do just fine without active ventilation.

    If you want to reduce infiltration, the best approach is to identify and seal air leaks -- not to use electricity to force indoor air through the existing leaks.

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