Log-Burning Fireplace Insert for Tight House
Martin Holladay’s 2013 article “All About woodstoves” and the april 2021 bs+beer episode “playing with fire” suggest it is possible to burn logs safely in pretty tight house. We *need* to burn logs at times due to frequent prolonged wintertime power outages in our rural community near nh-vt-ma border. We have a woodshed and a family member who keeps us well-stocked with seasoned hardwood from his woodlots, cut to whatever size we need. What brand/model of log-burning insert can we install in our fireplace? Chimney goes thru ridge, not along exterior wall. We are gutting whole house from inside and plan to make it tighter. We fear backdrafting because even tho we are buying ventless clothes dryer and makeup air apparatus for the hood on our elec range, we still have a kitchen exhaust fan, laundry exhaust fan, and 2 bath exhaust fans, all of which at times run simultaneously. We want to avoid opening a window when burning logs. Therefore, we need an insert that can bring outdoor combustion air straight to box. We prefer sealed combustion unit with window so we can see how fire’s doing at any moment without having to open door. The links to 2 different products in Martin’s 2013 article no longer work; furthermore, one product does not appear available in US, while other requires water tubes (?). A female participant (i believe architect) in 2021 bs+beer “playing with fire” episode says she has specc’d woodstoves for passivhaus projects. What brand/model? Are they available as fireplace insert or only freestanding woodstove? Thanks
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You are referring to Emily Mottram. I speak with her weekly and will ask about the brand/model she recommended. Stay tuned.
Thank you very much. I look forward to finding out
Curious about this also -- been researching inserts recently!
One place to get some information, anonymous, is the EPA database here: https://www.epa.gov/compliance/epa-certified-wood-heater-database
Unfortunately they don't separately categorize inserts vs. standalone stoves, but you can compare efficiency ratings, rated heat output ranges, and whether it's catalytic or not. Keep in mind that (for this year and next, at least), there's a 26% tax credit on woodburning appliances that are greater than 75% HHV efficiency -- unfortunately the selection of inserts that meet this criterion is pretty slim, and I'm pretty sure all are catalytic. Blaze King and Kuma are two that keep coming up in my searches -- of those, only Kuma accepts ducted outdoor air -- but there may be (I hope) others, and depending on your situation (ie how much of the work you're doing yourself and how much tax liability you expect) a unit that doesn't meet the 75% efficiency threshold but is lower cost may be cheaper overall than an expensive unit after the tax credit.
If you are "gutting the whole house", depending on the overall scope of work, you could also consider just removing the chimney & fireplace entirely and putting in a freestanding woodstove with a metal chimney.
On the outdoor air front, I recall reading that even ducted outdoor combustion air is no guarantee that you can't backdraft the stove -- a big ol' exhaust fan could still overpower chimney draft AND the little combustion air intake. In a Building Science Corp seminar I attended, Lstiburek concluded one day by saying just open a window when you want a fire!
Thank you, Jonny—very helpful advice! I am looking into the Kuma units to see if our existing fireplace will meet clearance requirements. If not, may have to rip out whole chimney as u say (hopefully not).
Here are a few more recommendations from Mike Maines and Emily Mottram: Morso, Hearthstone, and Rais.
Thank you--very helpful!
Looking at this too. I like the look of the Stuv 16-in and the Stuv-6. In a full remodel maybe the Stuv 30 free standing model?
All have "outdoor air kits" with the outside air coming either behind or underneath the unit.
I think they are "single burn rate" so if I understand correctly they basically just operate at one level of fire. I'm thinking this can be useful since the smallest Stuv-6 claims a burn rate of 34 000 BTU. I believe there are small burn rate models as well (as low as 16,000 BTU), although they don't seem to be on sale in the US so they probably don't meet EPA ratings.
https://stuvamerica.com/wp-content/uploads/2021/03/Fiche-Produit_Stuv-6_EN.pdf
Yet another helpful choice to look into—thanks, James!