Opinions on house size and firebox size

[TomMcDonald]

Hi experts,

I'm about to decide on a stove and would like some last minute assurance on a stove size.

I'm choosing between 2cbf stove and a 2.7cbf stove.

I have attached a rough plan of the house.

I live in Australia in a climate considered temperate. We usually burn from mid Autumn to early Spring.
Mid winter minimum temps can get to 23f or a bit less and daytime highs usually hover between 40f to 55f.
I've been told the climate is similar to coastal Pacific North West.

The roof is very well insulated but there's no insulation anywhere else. Cellular blinds throughout. I will probably insulate the walls and floors soon.

the pink squares are outlets for a ducting system that uses an inline fan to draw air from the ceiling about the heater to down the hall. These are perfectly legal in Australia and widely used. They work very well to transfer residual heat about the stove to other areas.

The blue square is the proposed woodstove area. This works for a number of reasons including existing furniture and the roof peak, trees, etc.

Total house area is around 1700sqf. Single level. All the bathroom and laundry doors are always closed.

Would appreciate any advice about firebox size.

Thanks,

Tom.

 

[begreen]

Both sizes can work. The smaller capacity stove will need more frequent reloads when it is very cold out but it should be able to keep up with the demand. Our next-door neighbor is heating their 1600 sq ft Pac NW home with a 2 cu ft Pacific Energy Spectrum (Super). The larger stove may be running only half-loads in milder weather, but it will have more capacity for a longer burn when the temperature is below freezing.

Their floorplan is more open. Are the pink squares intakes or exhaust (output)? Is there a intake or exhaust for this system in the big room housing the stove?

 

[TomMcDonald]

Both sizes can work. The smaller capacity stove will need more frequent reloads when it is very cold out but it should be able to keep up with the demand. Our next-door neighbor is heating their 1600 sq ft Pac NW home with a 2 cu ft Pacific Energy Spectrum (Super). The larger stove may be running only half-loads in milder weather, but it will have more capacity for a longer burn when the temperature is below freezing.

Their floorplan is more open. Are the pink squares intakes or exhaust (output)? Is there a intake or exhaust for this system in the big room housing the stove?

Thanks Begreen for the reply.

The pink squares are outlets. The inlet will be situated close to the stove, or wherever most heat accumulates. The intake is currently in place elsewhere in the big room but I'll move it when the new stove is installed. Ducting is insulated and in the ceiling.

Is it possible the 2.7cbf stove could suffer from issues like excessive creosote or low efficiency burning frequent half loads?

Tom.

 

[begreen]

Is it possible the 2.7cbf stove could suffer from issues like excessive creosote or low efficiency burning frequent half loads?

If run properly and the wood is dry, then creosote build-up should not be an issue. As long as the flue temps are warm enough, the flue walls don't get cool enough for creosote to condense. This is especially true with a non-cat stove on an interior chimney. The key is to burn dry wood and keep the flue temps above 250ºF at the top of the chimney.

In milder weather, this typically this means burning with a stove top around 500º and a similar flue gas temp inside the stove pipe. The fire is still hot enough for good secondary combustion, it's just the duration of peak combustion is shorter than with a full load of wood. Once it is in the coaling stage there is no more outgassing of the wood and no worry about lower flue temps which will decline with the stovetop temp at that stage of the burn.

 

[DuaeGuttae]

I’m not an expert like Begreen, but I live in a mild winter climate in the US at about 29 degrees north latitude and have some experience with a 2.5 cubic foot insert here. We see winter low temperatures in the 20s at times (occasional teens and very rare single digits), and highs can be in the 40‘s to 60’s for average. (We just saw 80 yesterday, but that was definitely above average.) We do run our stove at those temperatures especially if it’s a cloudy or windy day.

Our home is quite large, and the heat from the insert does not reach all of it. Nevertheless, we could overheat the main living area on a mild, sunny day if we ran a full load. (It’s a similar layout to where you’ll put your stove, in that we have an open kitchen/dining/family room area that’s wide open to an additional room. We also have stairs at the far end that lead to a partial upstairs. The heat from our stove does not travel to the other half of the downstairs, though.). We burn partial loads on sunny days for that reason without any difficulty. On really cold nights we do often burn full loads (not packed tightly usually because our wood is rather gnarly), and we’ll reload with partial loads during the day when we want a fire but don’t want to overheat. We really enjoy the spacious firebox, and we’ve not had any problem with creosote buildup in our long liner. We have good dry oak and cedar, and we can have hours of secondary burn even from a partial load. We don’t burn every day of winter, but we sure love having a fire on chilly days.

We had a 2.2 cubic foot stove in our last home, and we didn’t want to go smaller than that for this home. We prefer the slightly larger firebox just for the ease of loading (especially because our live oak wood is very twisty and curved, not anything like a straight split). 2.7 cubic feet is larger than what you probably need, but I think you could certainly make it work, and you might enjoy the extra space. 2.0 cubic feet would also work, I think, given your home size and climate, but you’d be trying to pack it a lot more full to have good overnight burns, I think, if that would be one of your goals.

How high are your ceilings, by the way? Standard eight feet or are they higher to help dissipate heat in your summers? I ask because woodstoves heat cubic footage even though they’re rated in square footage. It’s just something to keep in mind if you happen to have higher ceilings.

 

[TomMcDonald]

If run properly and the wood is dry, then creosote build-up should not be an issue. As long as the flue temps are warm enough, the flue walls don't get cool enough for creosote to condense. This is especially true with a non-cat stove on an interior chimney. The key is to burn dry wood and keep the flue temps above 250ºF at the top of the chimney.

In milder weather, this typically this means burning with a stove top around 500º and a similar flue gas temp inside the stove pipe. The fire is still hot enough for good secondary combustion, it's just the duration of peak combustion is shorter than with a full load of wood. Once it is in the coaling stage there is no more outgassing of the wood and no worry about lower flue temps which will decline with the stovetop temp at that stage of the burn.

Thank you. Good to know.

 

[TomMcDonald]

I’m not an expert like Begreen, but I live in a mild winter climate in the US at about 29 degrees north latitude and have some experience with a 2.5 cubic foot insert here. We see winter low temperatures in the 20s at times (occasional teens and very rare single digits), and highs can be in the 40‘s to 60’s for average. (We just saw 80 yesterday, but that was definitely above average.) We do run our stove at those temperatures especially if it’s a cloudy or windy day.

Our home is quite large, and the heat from the insert does not reach all of it. Nevertheless, we could overheat the main living area on a mild, sunny day if we ran a full load. (It’s a similar layout to where you’ll put your stove, in that we have an open kitchen/dining/family room area that’s wide open to an additional room. We also have stairs at the far end that lead to a partial upstairs. The heat from our stove does not travel to the other half of the downstairs, though.). We burn partial loads on sunny days for that reason without any difficulty. On really cold nights we do often burn full loads (not packed tightly usually because our wood is rather gnarly), and we’ll reload with partial loads during the day when we want a fire but don’t want to overheat. We really enjoy the spacious firebox, and we’ve not had any problem with creosote buildup in our long liner. We have good dry oak and cedar, and we can have hours of secondary burn even from a partial load. We don’t burn every day of winter, but we sure love having a fire on chilly days.

We had a 2.2 cubic foot stove in our last home, and we didn’t want to go smaller than that for this home. We prefer the slightly larger firebox just for the ease of loading (especially because our live oak wood is very twisty and curved, not anything like a straight split). 2.7 cubic feet is larger than what you probably need, but I think you could certainly make it work, and you might enjoy the extra space. 2.0 cubic feet would also work, I think, given your home size and climate, but you’d be trying to pack it a lot more full to have good overnight burns, I think, if that would be one of your goals.

How high are your ceilings, by the way? Standard eight feet or are they higher to help dissipate heat in your summers? I ask because woodstoves heat cubic footage even though they’re rated in square footage. It’s just something to keep in mind if you happen to have higher ceilings.

Thanks for the response.

Funnily enough I'm using a 2.5cbf insert now but have decided to sell the insert for various reasons, including that we're not happy with a blower constantly going, would prefer to be able to cook and have water on the stove top, and that we think we can heat the further reaches of the house more efficiently using a stove and ceiling vents. plus our particular hearth and exterior chimney aren't very nice.

Interesting point about not having to pack a 2.7 so full for an overnight burn. Although we don't always burn overnight (mostly due to the blower going on and off close to the end of the burn cycle in the wee hours) that is a consideration.

Ceilings are all 8'.

Thanks,

Tom.

 

[DuaeGuttae]

Thanks for the information about the ceiling height. That makes me feel more confident that either size of stove would suit your needs. What kind of wood is available to you? Mostly hard or soft? Straight or gnarly? That might be something to consider if you’re thinking of downsizing a firebox. Would you want the stove to burn all night if you didn’t have the blower issue?

Both of our ”stoves” have been inserts, mostly because the areas that need the heat the most have already been equipped with inefficient fireplaces. Turning those into something efficient has been a bonus. We do have to run a blower, but even at high it’s quite manageable noise. On low (where it is now for us since it’s a sunny afternoon and the stove is down to coals), it’s really inaudible.

I’m really a freestanding stove person at heart, and our first insert stuck out ten inches from the front of the fireplace precisely so that we could have a cooktop and more radiant heat. Our current insert sticks out only about five inches and has a convection top. We keep a kettle there but have never tried to cook on top since it would only be good for slow cooking but isn’t large enough for one of our Dutch ovens. I definitely understand the appeal, though, which is why I’ve never gravitated toward flush inserts. I’ll be interested to hear your experience in switching over from an insert to a freestanding stove.

 

[TomMcDonald]

Thanks for the information about the ceiling height. That makes me feel more confident that either size of stove would suit your needs. What kind of wood is available to you? Mostly hard or soft? Straight or gnarly? That might be something to consider if you’re thinking of downsizing a firebox. Would you want the stove to burn all night if you didn’t have the blower issue?

Both of our ”stoves” have been inserts, mostly because the areas that need the heat the most have already been equipped with inefficient fireplaces. Turning those into something efficient has been a bonus. We do have to run a blower, but even at high it’s quite manageable noise. On low (where it is now for us since it’s a sunny afternoon and the stove is down to coals), it’s really inaudible.

I’m really a freestanding stove person at heart, and our first insert stuck out ten inches from the front of the fireplace precisely so that we could have a cooktop and more radiant heat. Our current insert sticks out only about five inches and has a convection top. We keep a kettle there but have never tried to cook on top since it would only be good for slow cooking but isn’t large enough for one of our Dutch ovens. I definitely understand the appeal, though, which is why I’ve never gravitated toward flush inserts. I’ll be interested to hear your experience in switching over from an insert to a freestanding stove.

Hi again,

Yes I would like the option of burning overnight if possible. My wife likes waking up to a warm house but it means that the air is a little dry overnight for my taste (however, with a freestanding unit I could put a pot on it, currently have a flush insert).

Wood is very dense hardwood. Even our worst firewood is around the same density as American Oak, with a few good ones like ironbark and yellowbox being almost twice as dense. I can't be picky though and usually have a mixture.

A protruding insert sounds like a good compromise to me. However, the wife is also keen on a freestander. It's a shame, because there's a lot to like about inserts but I think in our situation we have the oppoortunity to switch so will.

I will report back with more information once we've made the switch.

 

[DuaeGuttae]

Wow. That sounds like good quality hardwood. With that many BTU’s, I would think you’d be able to burn overnight in a 2 cubic foot stove pretty easily. I can imagine you’d having a pretty long coaling stage with such dense wood. That’s when it’s nice to have some smaller softer wood to help burn the coals down.

That’s great that your wife is also keen on a freestanding stove. I read many times of wives on this forum who insist on flush inserts for the aesthetics. I’m more along the lines of the wife who likes the warm house in the morning. I sure hope you find that when you make the switch that you get the expected gains in heat.

How have you found the sizing of the 2.5 cubic foot insert to be for you? That’s probably the most telling of what will suit your needs best.

 

[TomMcDonald]

Wow. That sounds like good quality hardwood. With that many BTU’s, I would think you’d be able to burn overnight in a 2 cubic foot stove pretty easily. I can imagine you’d having a pretty long coaling stage with such dense wood. That’s when it’s nice to have some smaller softer wood to help burn the coals down.

That’s great that your wife is also keen on a freestanding stove. I read many times of wives on this forum who insist on flush inserts for the aesthetics. I’m more along the lines of the wife who likes the warm house in the morning. I sure hope you find that when you make the switch that you get the expected gains in heat.

How have you found the sizing of the 2.5 cubic foot insert to be for you? That’s probably the most telling of what will suit your needs best.

Hi,
I like the sizing of the 2.5. I think it's meant to be an E/W loader though. These new stoves I'm looking at are N/S loaders so there will be a bit of a difference. You're probably right about my experience with it telling me what I need to know.
Thanks for all the advice. I'll report back once a purchase has been made.