Stove recommendation for ICF house with 13-14' chimney

[ColoradoPine]

Hello! This is my first post, but I've already learned a lot by reading through these forums.

I'm building an ICF house on the Colorado Front Range, and I'm looking for a recommendation. The style of the house and roof pitch leave me preferring a 13-14' chimney height (from top of stove...15-16' from hearth floor), but it will be a straight up, insulated double wall pipe. I'll also have an OAK due to the very tight construction. The house is at about 6,000', so I think I'm going to need an easier breathing stove if I'm not willing to put in a taller pipe.

The house will be a ranch with a walkout basement (~1700 sq. ft. up and same sq. ft. down), but I'll also have central HVAC with separate zones for upstairs and downstairs. My main goal is to primarily heat the main level, which has an open floor plan, with the stove.

My priorities:

• Good burn time
• Modern aesthetic and good viewing window
• Work well with 13-14' straight chimney @ 6,000'

I like the Blaze King Sirocco 20.2 and the Boxer 24, but my concern is the chimney height requirement. I've heard the Regency F1500 and F2500 are easy breathers, but I probably won't get the super long burn times.

Also, keep in mind that ICF houses and very, very tight and well-insulated, so I need less stove than most would for 1700 sq. ft.

Btw, I plan to process my own wood, and I'll be burning mostly softwoods. Thanks in advance for all your help.

 

[begreen]

ICF homes can be very efficient, but if there are large glass areas then that can be the primary heat loss. The best thing to do is get the heat load calculations for the building design from the HVAC contractor. That will provide a better sizing guideline. If they show that just lighting, appliances, and humans will provide 75% of the heat, then a wood stove might be superfluous or more for power outages and a few evening fires on the coldest nights. This could be especially true if there is a lot of daytime solar gain.

The altitude will have an effect on draft. It would be ok to try on a 14' flue system, but be prepared to add a few more feet if weak draft is an issue. SBI (Drolet/Osburn), Pacific Energy, Regency all make easy breathing stoves. If a 2 cu ft stove will work out, the PE Super or Alderlea T5 is a good candidate as a compromise between easy breathing and longer burn time. The Woodstock Fireview is another stove to consider for the ability to burn low and slow for a long time, but they recommend a 15' minimum flue height, though we did have one regular user report it working well on a shorter flue, albeit at much lower altitude.

 

[stoveliker]

Regarding the need for heat (indeed, have it calculated properly) - just as an FYI, BKs can turn down (IF on a chimney that creates draft to specs) to a heat output of three and a half 1.5 kW plug in heaters.

BK suggests a 17.5 ft height (rather than a 15 ft height) for 5000-6000 ft elevation. That's a 2.5 ft extra. Given that this is solely due to the decrease in draft due to the elevation, it is likely that other stoves would need a similar (1/6) extension of the minimum height for those models.

 

[cahaak]

I would second Drolet and also mention that an OAK will help your stove to breathe easier and is critical in your application as you note.

 

[ColoradoPine]

Thank you for the responses. We will have a couple massive (12x8 and 8x8) sliding patio doors in the dining area, which is adjacent to the living area. And the living area has an 11' long window, although it will be triple paned. So, begreen, you raise a good point. I'm going to run a full heat load calculation soon, but my guess is we'll still be quite efficient because we do have pretty good windows and doors, the house will be super tight and we'll have R-60 in the attic. Even the basement slab will have 2" of closed cell underneath. Ceilings are also only 8'8" (it's a mid century ranch design).

I was able to put eyeballs on a Regency at a local dealer, and I really like the look of them. It seems I read about some people who push the limits on a short chimney and get away with it, but others don't. That's a really big concern of mine, and it makes me want to err on the side of an easy breather. I can be right at altitude-adjusted spec for the Regency F2500. I do also like the fact that it's a hybrid -- we can have a visible fire for ambiance in the evenings, but I can still turn it down and get an overnight burn.

Does anyone have any insight on the Lopi Evergreen Nex-Gen Hybrid? It seems similar on paper, but their stated chimney requirements are a tad higher than Regency's.

 

[begreen]

Check out the reviews for both stoves in their respective forums and in the ratings section.

 

[begreen]

Of the two, the Regency is an easier breather that will work better on a shorter flue system. The non-cat version is the F2450. It's a 2.4 cu ft firebox which may end up being oversized depending on the heat load requirements, stove locations, the size of the area being heated, and outside temperature.

 

[norts]

We’re approaching our first year anniversary of living in our ICF home that we designed/self-contracted and had similar considerations. We ended up going with the tulikivi 2450/92 due to efficiency, style and safety. But mainly because I’ve geeked on them forever.

Our home is 2500sqft slab-on-grade, Scandinavian shed style home (ranch basically) with a large open floor plan and the tuli in the center. We’re just shy of 16ft from the top of the tuli to the vault with a 8/12 pitch. We have a lot of south facing glass for passive heat gain with almost a 6ft overhang for summer months. All glass is triple pane fiberglass. We also have R-60 in the attic - cellulose in bedrooms, spray foam in vault.

I haven’t had any issues with the home being too tight but dug in a fresh air intake during excavation as a precaution. It’s hooked up to the stove but remains capped and buried outside. The installer didn’t think it would be an issue with stove being located in such a large space. He was correct. Only problem I’ve had is when I was trying to start a fire while the kitchen range hood was running. Oops.

We really didn’t experience a true winter here - but the tuli and icf preformed great during our one stretch below zero. Two burns a day kept the great room and kitchen around 74 and the back rooms in the upper 60s. Sunny days we only have one fire in the evening. We’ve burned about 1.5 cords of oak and ash - but it’s only March and anything can happen.

 

[DBoon]

I can understand your desire to keep the chimney height low(er) but you are at a higher altitude and this could become problematic, as others have pointed out.

My recommendation is to add 3 feet to your chimney and go with a cat stove. You would benefit from a cat stove given how tight your house is, and cat stoves require slightly taller chimneys because the cat slows down the exhaust (and the breathing). By choosing an easy-breathing stove, you'll oscillate between a very hot temperature and cooler temperatures. Other recommendations and reasoning is detailed below.

I have a very tight (non-ICF, blower-door tested at <1.0 ACH50) house. You will want to use an outdoor-air kit (OAK), for sure. If you open the stove for re-loading and forget to turn off your range hood, bathroom fan, or dryer (if you don't have a ventless dryer, which I have), you will realize pretty quickly that one of these is exhausting when smoke pours into the room from the wood stove door.

I would not recommend a stove that loads from the front (front-opening door) in a tight house. I had a Lopi 1750 in this house during construction and used it when the house was nearly fully air-sealed. It seemed to leak more smoke into the house with the door opened for reloading than in another house (that also had a Lopi stove, the Answer, basically a smaller version of the 1750). I can't imagine how much smoke would pour quickly in the room with a front-loading stove if I had an exhaust fan of some type also running. Yes, I know that you shouldn't open the stove until it is on coals but sometimes there is an unburnt piece of wood in the back and it will smoke when opened, or something falls against the glass and it needs to be dealt with to avoid the flow of air through the stove being heavily restricted. With a side-loading stove, air still circulates from back to top to front of the stove (along the glass), so when you open that side door it just swirls (mostly) in that pattern and doesn't come out the side door (unless you have an exhaust fan on).

With such a tight house (assuming that it is also well-insulated, with <20 kBTU/hour heat loss, I would recommend a smaller size stove with a catalytic converter. I use a Woodstock Keystone and love it for my 1750 square foot house in (what historically was) an 8000 degree day climate. That stove will heat the house on two loads of hickory a day down to 20 degrees F - below that temperatures I just run the radiant heat floors (at a reduced fluid temperature). If I had window coverings (coming soon) on my large R-2 picture windows, the stove would do better (to lower temperatures on hickory, or to similar temperatures with softer wood). The Keystone is a 1.4 cubic foot firebox. My guess is that your house will have a similar heat loss (20 kBTU/hour, more square footage but better insulated overall) but with softer wood out west you would benefit from a 2.0 cubic foot firebox. And if you get a cat stove you could run it lower and slower when days were warmer, something I really appreciate about my stove.

I love my smaller stove in my tight house and I love that it is a catalytic stove. It's really the perfect setup for me.

 

[jjam]

Hello! This is my first post, but I've already learned a lot by reading through these forums.

I'm building an ICF house on the Colorado Front Range, and I'm looking for a recommendation. The style of the house and roof pitch leave me preferring a 13-14' chimney height (from top of stove...15-16' from hearth floor), but it will be a straight up, insulated double wall pipe. I'll also have an OAK due to the very tight construction. The house is at about 6,000', so I think I'm going to need an easier breathing stove if I'm not willing to put in a taller pipe.

The house will be a ranch with a walkout basement (~1700 sq. ft. up and same sq. ft. down), but I'll also have central HVAC with separate zones for upstairs and downstairs. My main goal is to primarily heat the main level, which has an open floor plan, with the stove.

My priorities:

• Good burn time
• Modern aesthetic and good viewing window
• Work well with 13-14' straight chimney @ 6,000'

I like the Blaze King Sirocco 20.2 and the Boxer 24, but my concern is the chimney height requirement. I've heard the Regency F1500 and F2500 are easy breathers, but I probably won't get the super long burn times.

Also, keep in mind that ICF houses and very, very tight and well-insulated, so I need less stove than most would for 1700 sq. ft.

Btw, I plan to process my own wood, and I'll be burning mostly softwoods. Thanks in advance for all your help.

for sure go with the Regency F2500- or F3500, Blaze king will need more chimney height/ and yes you can turn the blaze king down but what is the point of running a stove at 5000. btus

 

[stoveliker]

The point is that he needs to know whether he needs 12000 BTUs (around the minimum of a BK) or much more. I.e. the point is not to run something low. The point is to run something *that provides the heat input he needs*. And for a new, well-insulated, tight home, that indeed could be around 12000 BTUs (for 20-30 hrs consistently between reloads).

Or he could need more.

The point is also whether he wants to cover *all* his heating needs, or most. All means you gotta have a stove that is too large for almost all the time - i.e. you have to run (too?) low most of the time to be able to heat that one time every 5 years where it's crazy cold. IF that's the goal, then get the biggest, baddest stove out there, and be secure in the fact you'll have enough heat when that event happens. And be frustrated with having to manage the stove with smaller fires and many reloads, and possibly even poor secondary performance because insufficient combustion is happening, all the other time.

Having a stove able to cover most heating needs, and supplementing with some other system at extremes, is ideal - *in my view*. You may think differently. That can be e.g. a heat pump for warmer days, or nat.gas or whatever is custom there on colder days, depending on your stove, or both.
I.e. for coldest days, have a base heat input from a stove, and modulate with a thermostat on top of that. You'll still burn much less gas during those coldest days because you already got the home up to some temperature with the stove.

A new home likely needs much lower BTU input.
I have run my stove at its minimum (I believe rated at about 11,900 BTU per hour - when they burned through one load in 30 hrs; I was able to run that one load thru the stove in 36-37 hrs, so I might have been a little lower output). So yes, this can be useful - IF that output provides what your home (and your wishes for temperature in that home).

And yes, there are many more low heat input days (aka shoulder season) than there are "too cold for the stove to keep up days" (the 3 days per winter it's really, REALLY cold) for a normal sized (for the home) stove.

The one thing that should not be compromised upon is the chimney height. The chimney is the engine of the stove. It is what drives it.
Therefore, get the priorities straight.

If priority number 1 is to have as short a chimney as possible, then take the Regency (BUT still have sufficient chimney height to avoid smoke roll out etc. - one really does not enjoy a stove that does not perform well because one has an undersized engine that runs the stove...)

If priority is to heat most of the time, find the stove that provides the heat output you need for that, and ensure the chimney complies with that stove.

Bottomline is that it's about what is your priority; chimney height, heating habits (all or most of the year), etc.

 

[ColoradoPine]

The point is that he needs to know whether he needs 12000 BTUs (around the minimum of a BK) or much more. I.e. the point is not to run something low. The point is to run something *that provides the heat input he needs*. And for a new, well-insulated, tight home, that indeed could be around 12000 BTUs (for 20-30 hrs consistently between reloads).

Or he could need more.

The point is also whether he wants to cover *all* his heating needs, or most. All means you gotta have a stove that is too large for almost all the time - i.e. you have to run (too?) low most of the time to be able to heat that one time every 5 years where it's crazy cold. IF that's the goal, then get the biggest, baddest stove out there, and be secure in the fact you'll have enough heat when that event happens. And be frustrated with having to manage the stove with smaller fires and many reloads, and possibly even poor secondary performance because insufficient combustion is happening, all the other time.

Having a stove able to cover most heating needs, and supplementing with some other system at extremes, is ideal - *in my view*. You may think differently. That can be e.g. a heat pump for warmer days, or nat.gas or whatever is custom there on colder days, depending on your stove, or both.
I.e. for coldest days, have a base heat input from a stove, and modulate with a thermostat on top of that. You'll still burn much less gas during those coldest days because you already got the home up to some temperature with the stove.

A new home likely needs much lower BTU input.
I have run my stove at its minimum (I believe rated at about 11,900 BTU per hour - when they burned through one load in 30 hrs; I was able to run that one load thru the stove in 36-37 hrs, so I might have been a little lower output). So yes, this can be useful - IF that output provides what your home (and your wishes for temperature in that home).

And yes, there are many more low heat input days (aka shoulder season) than there are "too cold for the stove to keep up days" (the 3 days per winter it's really, REALLY cold) for a normal sized (for the home) stove.

The one thing that should not be compromised upon is the chimney height. The chimney is the engine of the stove. It is what drives it.
Therefore, get the priorities straight.

If priority number 1 is to have as short a chimney as possible, then take the Regency (BUT still have sufficient chimney height to avoid smoke roll out etc. - one really does not enjoy a stove that does not perform well because one has an undersized engine that runs the stove...)

If priority is to heat most of the time, find the stove that provides the heat output you need for that, and ensure the chimney complies with that stove.

Bottomline is that it's about what is your priority; chimney height, heating habits (all or most of the year), etc.

Thank you -- this is very helpful. I'm still chewing on this.

 

[ColoradoPine]

I've done a heat load analysis and thought through things a bit more. I'm now leaning toward the Drolet Deco II due to its low chimney requirement (12'), modern look and generally good reviews. Its weakness for my application is burn time, but I'm not sure that's a dealbreaker. Loading it up before bed and turning it down should at least leave hot coals in the morning. At that point, I can reload on a cold day. On more moderate days, I probably don't need additional heat due to the very low heat loss of the home.

My heat load analysis (following the technique described here in the third comment: https://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/80957/afv/topic/Default.aspx):

U-Factors
Wall u-factor: .045
Ceiling u-factor: .0167
Average window u-factor: .19
Average patio door u-factor (can't get triple glazed in these): .28

MAIN LEVEL
Temp delta of 63 (99th percentile condition is 7 degrees, assumed indoor temp is 70 degrees)
sq. ft. of windows: 200 (heat loss of 2394 btu/hr)
sq. ft. of patio doors: 168 (heat loss of 2963 btu/hr)
sq. ft of wall: 1157 (heat loss of 3280 btu/hr)
sq. ft. of attic: 1700 (heat loss of 1785 btu/hr)
Total Heat Loss: 10,422 BTU/HR

BASEMENT
Temp delta of 63 (will be much lower than this in reality, but specific heat of soil is higher than that of air and varies with moisture conditions....modeling heat loss to soil is significantly more complex than my abilities allow, but I think I'm overshooting loss here.)
sq. ft. of .19 window: 50 (heat loss of 598 btu/hr)
sq. ft. of .28 patio door: 70 (heat loss of 1234 btu/hr)
sq. ft. of wall: 1157 (heat loss of 3280 btu/hr)
sq. ft. of slab: 1700 (heat loss of 7650 btu/hr)
Total Heat Loss: 12,764 BTU/HR

Total heat loss for entire house @ 99th percentile design contraint (7 degrees F): 23,164 BTU/hr

Obviously, the real world value could be a bit higher than this due to air movement and human error when installing windows, doors and insulation. But I've also probably overstated heat loss in the basement due to the smaller temp delta of soil.

If you recall, my goal is really just to heat the main level largely with the wood stove, (although I'll be utilizing a multi-split heat pump that allows individual rooms to run on their own thermostat). So my real target number here is 10,422 BTUs, but my stairway to the basement is open and is rather close to the fireplace. So I'll welcome some heat making its way to the basement, too.

The Drolet Deco II, which is a 1.86 cu. ft. firebox stove, has a max output of 52,200 BTUs (I'm using the lower, non-cordwood figure because I'll mostly be burning softwoods) and a minimum output of 9,800 BTUs/hr. I'm assuming that latter figure is based on the cordwood number, so dividing the max regular output of 52,200 by the stated seven hour burn time, I can guess that I could theoretically drop down to an average output of 7,457 BTUs/hr.

That's well below my 10,422 BTUs/hr design constraint, so I don't think I'm running the risk of not being able to turn the stove down low enough, especially when good airflow to the basement exists in close proximity to the stove.

I'd love to hear everyone's thoughts. It's nice that the Drolet is cheap, but I'm willing to spend the money to get the right stove.

 

[stoveliker]

Sounds like a decent plan.
There won't be much heat going down the stairs (to the basement), though.

 

[begreen]

The Deco II is primarily an E/W loader unless the wood is cut to 12-14". Consider the Drolet Deco Nano instead. The usable loading capacity is the same but the Deco Nano is a N/S loader so you will get maximum load capacity for those very cold days. In milder weather run partial loads.

 

[Wisco Shepherd]

The Deco II is primarily an E/W loader unless the wood is cut to 12-14". Consider the Drolet Deco Nano instead. The usable loading capacity is the same but the Deco Nano is a N/S loader so you will get maximum load capacity for those very cold days. In milder weather run partial loads.

Agreed, I really liked this stove if i end up building a 4 season porch this will be heating it.

 

[EbS-P]

I've done a heat load analysis and thought through things a bit more. I'm now leaning toward the Drolet Deco II due to its low chimney requirement (12'), modern look and generally good reviews. Its weakness for my application is burn time, but I'm not sure that's a dealbreaker. Loading it up before bed and turning it down should at least leave hot coals in the morning. At that point, I can reload on a cold day. On more moderate days, I probably don't need additional heat due to the very low heat loss of the home.

My heat load analysis (following the technique described here in the third comment: https://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/80957/afv/topic/Default.aspx):

U-Factors
Wall u-factor: .045
Ceiling u-factor: .0167
Average window u-factor: .19
Average patio door u-factor (can't get triple glazed in these): .28

MAIN LEVEL
Temp delta of 63 (99th percentile condition is 7 degrees, assumed indoor temp is 70 degrees)
sq. ft. of windows: 200 (heat loss of 2394 btu/hr)
sq. ft. of patio doors: 168 (heat loss of 2963 btu/hr)
sq. ft of wall: 1157 (heat loss of 3280 btu/hr)
sq. ft. of attic: 1700 (heat loss of 1785 btu/hr)
Total Heat Loss: 10,422 BTU/HR

BASEMENT
Temp delta of 63 (will be much lower than this in reality, but specific heat of soil is higher than that of air and varies with moisture conditions....modeling heat loss to soil is significantly more complex than my abilities allow, but I think I'm overshooting loss here.)
sq. ft. of .19 window: 50 (heat loss of 598 btu/hr)
sq. ft. of .28 patio door: 70 (heat loss of 1234 btu/hr)
sq. ft. of wall: 1157 (heat loss of 3280 btu/hr)
sq. ft. of slab: 1700 (heat loss of 7650 btu/hr)
Total Heat Loss: 12,764 BTU/HR

Total heat loss for entire house @ 99th percentile design contraint (7 degrees F): 23,164 BTU/hr

Obviously, the real world value could be a bit higher than this due to air movement and human error when installing windows, doors and insulation. But I've also probably overstated heat loss in the basement due to the smaller temp delta of soil.

If you recall, my goal is really just to heat the main level largely with the wood stove, (although I'll be utilizing a multi-split heat pump that allows individual rooms to run on their own thermostat). So my real target number here is 10,422 BTUs, but my stairway to the basement is open and is rather close to the fireplace. So I'll welcome some heat making its way to the basement, too.

The Drolet Deco II, which is a 1.86 cu. ft. firebox stove, has a max output of 52,200 BTUs (I'm using the lower, non-cordwood figure because I'll mostly be burning softwoods) and a minimum output of 9,800 BTUs/hr. I'm assuming that latter figure is based on the cordwood number, so dividing the max regular output of 52,200 by the stated seven hour burn time, I can guess that I could theoretically drop down to an average output of 7,457 BTUs/hr.

The l by That's well below my 10,422 BTUs/hr design constraint, so I don't think I'm running the risk of not being able to turn the stove down low enough, especially when good airflow to the basement exists in close proximity to the stove.

I'd love to hear everyone's thoughts. It's nice that the Drolet is cheap, but I'm willing to spend the money to get the right stove.

Rough math says one pound of wood gives 4.5k btus per pound. Say You could get close to say 33 pounds in the stove. Say you have 6 hour burn that averages 25k btus per hour.

Personally I’d go for a N/S loader something that I don’t have to get up to reload. I have a 1.6 cu ft stove with aheatingold calc of about 29k btus. It’s not as fun when it’s that cold. Takes planning and timing when it’s cold.

Get something N/S that could burn through night. My guess is you will be burning at pine. It’s great when you need to push a stove burns fast and Hot with little ash. But that means more frequent reloads.