Which stoves have outside air kits that are really tight?

Far too early in my design process to get serious about math like that. In general we are planning to build 900 to 1500 sqft - so already to big a range to pick a wood stove and start talking about cfm.

Another idea is to put the oak through an interior wall, with the intake for the wood stove low on a bathroom wall between the comode and bath tub.

My local experience with my local setup is i can do hot reloads with loadibg door open 1 minute or less when my cord wood is at or under 16%mc. Above that i have to keep the loading door cracked a little longer...

I suggest two more sips of the single malt and post again in the morning.

Just kidding, let us know how it goes, Your climate is a challenging one I'm sure. I've seen varying thoughts on the passivehaus thing, and have nothing to offer, but I think it bears a lot of research before committing to a design.

Sprinter said:

{one} question I have is, how many CFM of combustion air are you using when considering a design for an hrv system, etc? Being down here in more moderate climate, these things don't come up that often.

{2}It just seems to me that any interior leakeage from a decent OAK stove would be nearly meaningless, but I'm willing to learn. It seems that a specific CFM quantity would be essential.

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I do look at sealing a little harder than many regulars here. In a typical winter i spend 10-14 days maintaining the interior of my home 120-130dF warmer than outdoor ambient, with an additional 4 months in the 100-110dF difference club. I also own a 35 year old house, so I prefer air turnover and slightly higher BTU usage to a totally sealed ticking time bomb of mold. If I can feel an air leak with my hand, say around the trim of a window, I can practically see dead presidents flying out of my back pocket into the fuel truck.

Ultimately, CFM plan for the HRV will depend on whether or not the stove is using an OAK, and how effective the oak is.

From the 'passivehaus" cert perspective that I think got this thread started in the first place, the total system, oak, combustion box and chimney - and the seals between wall and oak and the seal between chimney and roof or ceiling - the total system will have to prove it is airtight up to whatever level of applied suction to earn "passivehaus" certification.

Siting the oak into the bathroom will defeat "passivehaus" because the suction pump will be pulling air down the chimney, through the stove box and out into the bathroom before any meaningful vacuum is achieved.

IIRC there are degrees, levels of certification available depending on how much vacuum the building can withstand. One thing I didn't find in my somewhat cursory reading was the "official" "certified" test procedure for blocking the actual HRV pipes so the seals between the building shell and HRV tubing can be vacuum tested...

Its all very though provoking. On the one hand I do want thick insulation and good air seals. Do i really want a house built so tight I HAVE to utilize an energy using HRV to maintain indoor air quality? Ultimately that scenario is a home that is unhealthy to live in without electricity. I am frankly reticent to commit to living in a home that is passively self destructive and requires the ongoing active (electricity consuming) maintenance of an HRV to be livable.

I like HRVs, it would be foolish to build new construction up here and not utilize one; but to build so tight that the HRV has to be running to keep the building habitable, I am not sure I want to go that far.

Poindexter said:

Its all very though provoking. On the one hand I do want thick insulation and good air seals. Do i really want a house built so tight I HAVE to utilize an energy using HRV to maintain indoor air quality? Ultimately that scenario is a home that is unhealthy to live in without electricity. I am frankly reticent to commit to living in a home that is passively self destructive and requires the ongoing active (electricity consuming) maintenance of an HRV to be livable.

I like HRVs, it would be foolish to build new construction up here and not utilize one; but to build so tight that the HRV has to be running to keep the building habitable, I am not sure I want to go that far.

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I wish I could respond authoritatively, but I'm sure I would agree with those concerns. As in every design, whether it's building, mechanical, electronic, or whatever, there are compromises that must be made. I'm no hrv expert at all, but the concept sounds right, as long as it's properly implemented.

Poindexter said:

Ultimately, CFM plan for the HRV will depend on whether or not the stove is using an OAK, and how effective the oak is.

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This is up to you, but I honestly don't think you should worry too much about a little bit of OAK leakage. If you really are concerned about it, any leak spots can be easily sealed. I could do it in two minutes with mine. No potential leak area is in a hot area.

A typical OAK is 4" diameter. A little tiny leak would be insignificant compared to that. Really, any well designed stove with an OAK provided should work well for you. If in doubt, seal it better. BTW, the best place to get the fresh air is from a ventilated crawlsplace if available. It does need to be sheltered in some way from wind and pressure differential but that can be done in various ways.

Poindexter said:

..... Do i really want a house built so tight I HAVE to utilize an energy using HRV to maintain indoor air quality? Ultimately that scenario is a home that is unhealthy to live in without electricity. I am frankly reticent to commit to living in a home that is passively self destructive and requires the ongoing active (electricity consuming) maintenance of an HRV to be livable.

I like HRVs, it would be foolish to build new construction up here and not utilize one; but to build so tight that the HRV has to be running to keep the building habitable, I am not sure I want to go that far.

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The problem with the philosophy that "the house should be tight, but not too tight - the house has to breathe" is that as a guideline for building a new house it just doesn't work. Air leakage, bringing "fresh air" into a house, is driven by pressure difference, which comes from both wind pressure and air temperature (density) difference. Air leakage is worst in windy, bitter cold weather, and mostly nonexistent in windless, mild temperatures. There is simply no way to "design" in the right amount of air leakage that works at any set of outside conditions. Even if you could, leakage, and thus "fresh air" for the occupants, would be wrong for any other set of conditions. At its worst, leakage could be anything from an awful waste of energy and an uncomfortable house to excessively low, making the interior stuffy and unhealthful. Worst, you can't control leakage, other than by opening windows (right, in a Fairbanks winter, huh?). Then, too, do you really want your "fresh air" filtered through the insulation in the walls, which become fouled with dust, dead insects, rodent feces, etc., a filter you can't clean or change?

So basically the only thing that does work is to make the house as tight as you can and provide mechanical ventilation, something you can control. In Fairbanks, that system would indeed be an HRV, for energy efficiency. Yes, it does consume power, but that's small compared to the energy to keep the place warm, even if it's a superinsulated house.

DickRussell said:

There is simply no way to "design" in the right amount of air leakage that works at any set of outside conditions. Even if you could, leakage, and thus "fresh air" for the occupants, would be wrong for any other set of conditions. At its worst, leakage could be anything from an awful waste of energy and an uncomfortable house to excessively low, making the interior stuffy and unhealthful. Worst, you can't control leakage, other than by opening windows (right, in a Fairbanks winter, huh?).

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This, exactly.

I did find a .pdf from the passivhaus people, in English, air tightness and air pressure testing: http://www.passivhaus.org.uk/filelibrary/Primers/Passivhaus-Airtightness-Guide.pdf

Our current floor plan pencil doodles have a high CFM exhaust fan over the cook stove with outlet on the east wall of the house near the SE corner, and a very small window on the north wall near the NW corner in the master bath - very well shaded - for drawing cool air through the house when the air is clean and the temperature suitable.

Certainly when pollen counts are very high or forest fire smoke is blowing into town we'll use the HRV to filter the incoming air rather than opening a window...

Also, we are planning to have a couple dogs, with permanent pet door from the house into the arctic entry, and another permanent pet door from the arctic entry to the outdoors. Arctic entry basically insulated on all six sides, heated. Like an airlock, a way to come and go from indoors to outdoors while losing minimal heated air out the open door. Convenient place to hang you parka and leave your snowboots too, sort of a cold weather mud room.

Setting the floor of the arctic entry 12" below the floor of the rest of the house should take a big bite out of cold air intrusion, but likely the dog doors will be opable to dogs only a few hours per day in the coldest part of the year.

Other than the wood stove piping and the cook stove exhaust and having a bunch of opable windows, I am otherwise theoretically enthusiastic about passivhaus. I am done having bacon grease recirculated in the house by the fan over the stove.

Sprinter said:

I suggest two more sips of the single malt and post again in the morning.

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I'll get right on that.

I think ultimately that if my yet to be built envelope makes passivhaus cert with HRV but before the dog doors, before the wood stove and before the cook stove vent fan ~~ I will be very happy with the overall performance of the envelope.

I would expect any leakage around the OAK to be trivial, and right next to the wood stove. I will insist on the chimney being weather tight, but pin hole leaks in the telescoping flue between the firebox and chimney collar aren't going to break my heart. I got to keep the pipe swept without going up on the roof with 3' of snow up there and it's -20dF outdoors.

The wife and I do need to spend more time looking at cook stove fans. I just hate having cooking grease merely spread around the kitchen by a recirculating fan in the hood. I want a darn vent fan so i don't have to keep cleaning the cabinets every couple weeks. Already I cook all the meat I can outdoors rather than inside the house.

The dog doors are troublesome, but I want the dog to be able to go outside to potty without me having to get out of my chair. Explain the concept, demonstrate the door, educate the dog, get on with my life. Good boy!!

Pencil plans call for three man doors in the arctic entry, one to the garage, one to the back yard and one to the house, with two dog doors, one to the house and one to the fenced back yard. Wondering about having one arctic entry 12" before the floor level of the main house, and a second one 24" below the floor level of the main house, route the dogs through both.

If I made the lower one big enough and part of the garage slab I could maybe put a masonry heater in it with one face heating the garage overnight, and a second face radiating into the house. My wife parks outside at her office, reheating her car inside the garage over night every night is something I currently have to burn oil to do.

@John Ackerly , I don't know of an OAK that seals or doesn't seal well enough to make vacuum to meet passivhaus. I am sure it can be done. At my house, the seal between the stove collar and flue is NOT tight enough to make passivhaus either. I suppose it could be done, but once a vacuum tight oak/firebox/chimney is installed the only way to reliably clean that pipe and continue to meet passivhaus is going to be brushing from the top down no matter the weather- and sucking ash out from behind the cat is going to be problematic for the guy standing on the roof no matter how nice the weather.

yes there are top flue seal systems ( can also be called a Damper) that remotely open and close- some have been around longer than most of us. Real early ones used chains up the flue the more affulent types could have those wrapped on a cylinder turned externally by a crank or wheel to activate. Most new styles are RF controlled as the IFR like your TV and such wouldn't work through the roof and walls. To be fair most that I have seen have been for brick and mortar type flue construction but no reason it can't be adapted to round pipes or even oval as it isn't much different than that flapper on top of a tractor exhaust pipe ( that's there to keep rain out of the system) except that it is a positive open or closed arrangement. They are not meant as a method of control on the heating system below. Would work great for the OP as was stated about being careful of flue draft reversals.

I had some links to 3 different rf activated motorized units on another box that self destructed several years ago, But I can not find any reference to them at this point in time. they were of European mfg. Only one other that was set up for use with Gas fired fireplaces tied into the gas valve as an integrated system. On that opening the top hat would begin the sequence of ignition and burning automatically.
Course the manually operated chain systems for fire places and ( one place offers an adapter to round pipe that i came across) could be motorized for a remote function.
It isn't rocket science but there is the issue of creosote build up- but we all burn " Properly dried fuel" so that shouldn't be a particular problem that would prevent proper operation with no more maintenance than the chain/ cable pull type. Perhaps those units I was thinking of are no longer made - insufficient interest/ sales will do that real quick in our current mfg. society. There may have been other difficulties - I have no idea.
Somewhat like the super duper stove system from an Aussie that was bought into by a stateside firm in the southern section of states- has been squat about that since