Hi, We are working on plans for a small ICF home (729 sq/ft main level + loft) desiring a wood stove with medium size box for better loading of logs and fire view (ie Regency F2450). ICF homes are known for their tightness being extremely well insulated (concrete and foam). Since the house is so tight I was thinking the stove should have a direct outside air input vent which is available as an add on for this stove. Property is at a high elevation 9000' or so. Primary heat when the stove is not on will be radiant floor fueled by propane. I am considering a ductless HRV vent for healthy air exchange on the main level. Does this sound like a good idea and what would be the best area for a ductless single unit HRV placement so as not to cause unintended problems for the stove when in use?
Ductless HRV proximity to stove with Direct Vent
- Thread starter ftgarland
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Mechanical code calls for any return air to be at least 10 ft. away from the stove.
The F2450 sounds like it could be oversized for ICF construction and only 749 sq ft heated. ICF houses can require very little heat. What is the size of the propane boiler for the passive heat? Where is this house located?
The F2450 sounds like it could be oversized for ICF construction and only 749 sq ft heated. ICF houses can require very little heat. What is the size of the propane boiler for the passive heat? Where is this house located?
begreen, Thanks for taking the time to reply. The sq footage with open loft included would be approx. 1124 sq. ft. Property is located in south central Colorado in Costilla County in the mountains at 9100 feet, They really don't have any building codes and apparently rely upon the state codes only. Not sure what the size of the propane burner will be at this time. Do you have any suggestions for a more suitable stove for my preferences (I'd like it to accommodate standard size log, that would normally be available if you had them delivered as well as a larger window for viewing the fire and be able to burn for close to 10 hours through the night. I was looking at Regency because it seems to be a "better" brand for durability. If the stove has a direct fresh air intake vent should I consider the ductless HRV as just something for better quality inside air and really nothing affecting the stove burn, assuming it's at least 10 feet away?
I am hesitant to recommend a stove until the heat loss and system sizing calculations are done. A well-built and sealed ICF house can be very efficient, especially if the number of windows is kept reasonable and they are high R-value windows. In milder winter weather the heat generated in the house by lighting, cooking, refrigeration, etc. may be enough.
In non-cat, the PE Super is worth considering, but if the heating calculation shows low BTUs are adequate for say 80% of the heating season, then a catalytic stove like the BK Chinook or Sirocco or Woodstock Fireview may be a better fit.
In non-cat, the PE Super is worth considering, but if the heating calculation shows low BTUs are adequate for say 80% of the heating season, then a catalytic stove like the BK Chinook or Sirocco or Woodstock Fireview may be a better fit.
Thanks for your input. I'm new to wood stoves and only have experience with natural gas Fireplace logs and a wood burning fireplace. We miss the real wood burn heat generation and view. If the stove has a direct fresh air intake vent should I consider the ductless HRV as just something for better quality inside air and really nothing affecting the stove burn, assuming it's at least 10 feet away?
stoveliker
Minister of Fire
I'd be hesitant to put the hrv within 10 ft, even if you have a fresh air connection to the stove. The reason is that the fresh air connection can be easily disconnected leading to an unsafe install (as the hrv would not be easily moved).
Other things to keep in mind:
Make sure the chimney is tall enough. You likely have to add about 8 ft to the minimum recommended height for the stove because you are at high elevation.
Do you have wood already stacked for next year? Modern stoves want dry dry wood. They'll be a pita if one tried to burn insufficiently dried wood. (But will be fantastic and efficient with dry wood.) Often what one can buy as "seasoned" is not dry enough.
Other things to keep in mind:
Make sure the chimney is tall enough. You likely have to add about 8 ft to the minimum recommended height for the stove because you are at high elevation.
Do you have wood already stacked for next year? Modern stoves want dry dry wood. They'll be a pita if one tried to burn insufficiently dried wood. (But will be fantastic and efficient with dry wood.) Often what one can buy as "seasoned" is not dry enough.
The HRV is to improve indoor air quality year-round by bringing in fresh air to breathe. This is especially important in new construction where products are outgassing. Finishes, carpeting, furniture, etc. can emit fumes for a long time, so will cooking.
Stoveliker, Thanks for your advise. Just to clarify, if we go with a direct fresh air vent to the stove it's really for better overall fresh air room quality and shouldn't affect the stove burning performance? If that's the case we may just move it to the kitchen area. As far as wood goes, we have several years of dead wood lying and standing on our 3 acres. Our mountain property was devastated in the "Spring fire" in 2018. Good advise never the less to know we should have a season of wood delivered for the next year to ensure it's not green when needed.
stoveliker
Minister of Fire
I am not sure I understand the question, so I may be overly "elementary" here. If so, apologies.
The fresh air kit (or outside air kit) for the stove, pipes in air from outside directly into your stove. That does not really affect the room air quality either way as it's a (mostly) closed circuit from outside, to your stove, into the chimney to outside - unless your outside air is "dirty" in which case avoiding having air leak in is a good idea (which might only be the case in wildfire season, where you live, I surmise). This is because the stove needs air to burn, and without an outside air kit, it's using room air. I.e. it's sucking air from your room, uses it to burn the wood, and dumps it into the chimney. All due to the draft, i.e. low pressure in the chimney. The implication is that new air has to leak into the room/home.
For tight homes, air leaking in is minimized, and that can lead to problems burning the stove (smoke roll out etc).
An outside air kit avoids this. That is its main goal. It is not meant to keep the air in the home at a higher quality level (other than indirectly by avoiding smoke roll out for too-tight homes).
The HRV is meant to refresh air in the home, i.e. to keep the air quality in the home better, and will (should) not affect the stove burning negatively (in fact, the HRV will avoid negative pressures in the home/room, which might help avoid smoke roll-out issues).
So yes, if you install the stove, with or without the outside air kit, I would put the HRV in regardless if your home is tight: if you don't have the outside air kit, you need the make-up air leaking in thru the HRV. If you do have the outside air kit, you still want to maintain a fair air quality in the tight home.
And yes, if you have the opportunity to move the HRV to another room, e.g. kitchen, that would be a good idea, imo.
The fresh air kit (or outside air kit) for the stove, pipes in air from outside directly into your stove. That does not really affect the room air quality either way as it's a (mostly) closed circuit from outside, to your stove, into the chimney to outside - unless your outside air is "dirty" in which case avoiding having air leak in is a good idea (which might only be the case in wildfire season, where you live, I surmise). This is because the stove needs air to burn, and without an outside air kit, it's using room air. I.e. it's sucking air from your room, uses it to burn the wood, and dumps it into the chimney. All due to the draft, i.e. low pressure in the chimney. The implication is that new air has to leak into the room/home.
For tight homes, air leaking in is minimized, and that can lead to problems burning the stove (smoke roll out etc).
An outside air kit avoids this. That is its main goal. It is not meant to keep the air in the home at a higher quality level (other than indirectly by avoiding smoke roll out for too-tight homes).
The HRV is meant to refresh air in the home, i.e. to keep the air quality in the home better, and will (should) not affect the stove burning negatively (in fact, the HRV will avoid negative pressures in the home/room, which might help avoid smoke roll-out issues).
So yes, if you install the stove, with or without the outside air kit, I would put the HRV in regardless if your home is tight: if you don't have the outside air kit, you need the make-up air leaking in thru the HRV. If you do have the outside air kit, you still want to maintain a fair air quality in the tight home.
And yes, if you have the opportunity to move the HRV to another room, e.g. kitchen, that would be a good idea, imo.
stoveliker
Minister of Fire
One further thought I had for if the stove would ever be run without the outside air kit: do put the hrv on the same floor as the stove (there can be pressure differences between floors, though that may be less in a very tight home).
The fireview is a heater! I would remove that from the list. Might be the best heating stove I’ve ever had, given its size. It would blow you out of 1200’ with good insulation!
The Fireview lists one of the lower BTU outputs on low. Less than a BK on low. Does it not perform well at that output?
Poindexter
Minister of Fire
My next home is going to have an HRV and a wood stove with an outdoor intake. However, I am not familiar with ductless HRV.
In my current home I am feeding conditioned indoor air to the air intake on my wood stove for combustion air. There is no good reason to do this in a healthy home, but I am in a 1980 build with some mold issues.
With a traditional ducted HRV system putting the wood stove on its own air circuit - outside air intake -> firebox -> chimney -> outside exhaust means the wood stove is decoupled from the HRV system unless the loading door to the stove is open. My two year old plan (knowing the technology would advance in the meantime) was to have a lighted wall switch somewhere near the woodstove so when the HRV switch is lit the loading door to the woodstove can be opened, but if the switch is lit late at night with the stove running, the switch can be flipped back to dark.
I think insisting on a stove that can run on regular 16" cordwood is a good idea. There might be a couple market pockets here and there where 12" or 20" splits are readily available, but I don't know where they are. Local to me it is a special order product no cutter really wants to deal with.
I have no guesses on what stove might be suitable for this install. Certainly the BTU output rating of the propane boiler for radiant in floor heating - sized by a local experienced professional- would be a good place to start.
Good luck and best wishes.
In my current home I am feeding conditioned indoor air to the air intake on my wood stove for combustion air. There is no good reason to do this in a healthy home, but I am in a 1980 build with some mold issues.
With a traditional ducted HRV system putting the wood stove on its own air circuit - outside air intake -> firebox -> chimney -> outside exhaust means the wood stove is decoupled from the HRV system unless the loading door to the stove is open. My two year old plan (knowing the technology would advance in the meantime) was to have a lighted wall switch somewhere near the woodstove so when the HRV switch is lit the loading door to the woodstove can be opened, but if the switch is lit late at night with the stove running, the switch can be flipped back to dark.
I think insisting on a stove that can run on regular 16" cordwood is a good idea. There might be a couple market pockets here and there where 12" or 20" splits are readily available, but I don't know where they are. Local to me it is a special order product no cutter really wants to deal with.
I have no guesses on what stove might be suitable for this install. Certainly the BTU output rating of the propane boiler for radiant in floor heating - sized by a local experienced professional- would be a good place to start.
Good luck and best wishes.
EbS-P
Minister of Fire
Been going down the HVAC rabbit hole.
Thoughts. No equipment can be chosen before you have a load calc and a blower door test. Full stop. Put it in writing with contractors. If they won’t do it don’t use them. You have one chance to do it “right” the first time. (It’s not going to be perfect but right means after you get COA the fixes are minor tweaks.
Aa s for HRV. Through wall or ducted. I’m of the feeling that it needs to be variable speed and connected to some Smart Controler. CO2 monitor is a plus. It needs good filtration. You need to have the ability for a tight house to go into. Bio defense mode. Keep a high quality merv filter with actives carbon ready for wildfire season.
I’d lean ducted but to tie it into the hvac duct so all rooms get fresh air. And keep its filter located near the other hvac filter so they can always be changed together. Is it overkill maybe but if your blower door test is really low then no it’s not.
As for a stove can’t say until we get a load calc.
Was listening to an podcast and a remodel in Alaska, Anchorage I think 1800 sq ft came up with some stupid low load calc like 14k btu and they installed a 12k heat. I don’t have the numbers correct but the point is it was such a low heating load wood was never considered. They plan to bake cookies in the coldest days to supplement the heatpump.
At 9000’ in CO you should absolutely have a backup heat plan.
As for HRV size recommendation is one ventilated fresh air exchange ever 4-5 hours. More if more people are there. For my 3000 sq ft with 8’ ceilings it works out to be 80 cfm.
Thoughts. No equipment can be chosen before you have a load calc and a blower door test. Full stop. Put it in writing with contractors. If they won’t do it don’t use them. You have one chance to do it “right” the first time. (It’s not going to be perfect but right means after you get COA the fixes are minor tweaks.
Aa s for HRV. Through wall or ducted. I’m of the feeling that it needs to be variable speed and connected to some Smart Controler. CO2 monitor is a plus. It needs good filtration. You need to have the ability for a tight house to go into. Bio defense mode. Keep a high quality merv filter with actives carbon ready for wildfire season.
I’d lean ducted but to tie it into the hvac duct so all rooms get fresh air. And keep its filter located near the other hvac filter so they can always be changed together. Is it overkill maybe but if your blower door test is really low then no it’s not.
As for a stove can’t say until we get a load calc.
Was listening to an podcast and a remodel in Alaska, Anchorage I think 1800 sq ft came up with some stupid low load calc like 14k btu and they installed a 12k heat. I don’t have the numbers correct but the point is it was such a low heating load wood was never considered. They plan to bake cookies in the coldest days to supplement the heatpump.
At 9000’ in CO you should absolutely have a backup heat plan.
As for HRV size recommendation is one ventilated fresh air exchange ever 4-5 hours. More if more people are there. For my 3000 sq ft with 8’ ceilings it works out to be 80 cfm.
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