Warming basement with in-line ventilation fan
GBA has given me enormous amounts of information over the last two years, but I finally have a question that I haven’t been able to answer through searching this site.
I am trying to come up with a long term plan for slowly retrofitting a 1930s farmhouse in Conway, New Hampshire, zone 6A (~7,700HDD). My wife and I have owned it for one year. The 2-story house is 1,200 square feet, with R15 cellulose plus R3 polyiso on the walls, R18 cellulose in the attic, cheap low-e double pane replacement windows, and drafts throughout. The cellar has uninsulated walls (CMU and some granite block), a dirt floor, and a 150sf unvented crawl space below an addition. The crawl space is dry and insulated (R20 walls, R8 floor).
Last winter we heated with a 35,000 BTU wood stove (primary) and four supplementary oil-filled space heaters. After 6 years of heating with wood at our old place, we plan to continue for the foreseeable future.
For several reasons we’re tackling the wet cellar first. In addition to a holistic plan to dry our cellar, we plan to insulate to R6 underslab with R20 reclaimed foam on the walls. We’ll be hiring a sprayfoam contractor to seal/insulate the rim beam and granite blocks.
Last winter we had to keep a 5000BTU space heater running almost continuously in the cellar to keep it over 50 degrees F. The wood stove is on the first floor, and it kept the first and second floors around 60 to 65 degrees.
I would like to keep the plumbing in the cellar from freezing without the energy penalty of the space heater. My thought is to use an inline fan to draw warm air into the cellar, via the crawlspace. I would first add vents in the floor between the first floor and the crawl. Then I’d run a very short duct through the sill beam that separates the crawl space from the rest of the cellar. An inline fan would draw air from the crawl space into the cellar.
Could this be an elegant solution to ventilating the crawlspace and keeping the pipes thawed? Or are these just the ramblings of a syphilitic mind? And if it might work, what size fan would be appropriate?
Thanks for your time,
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