Can a wood stove be oversized for a space?

[jcbmv11]

I have a friend who claims that bigger wood stoves require bigger fires to keep them running properly.

I am looking at an Jotul Oslo. The space it’s going in is rather small, but I just figure I can run a smaller fire.

I don’t want to be stuck in a room is overheated. Looking for your thoughts.

 

[Vg3200p]

You can build a small fire in a big stove. Can't build a bigger fire in a smaller stove. I learned the hard way. Buy big

 

[heat my feet]

I have a Jotul F100cb. Great little stove. My house is 850+/- sq. ft. I light it in the morning and let it go out when I go to work. I light it when I get home and let it go out at bed time. I like a chilly house for sleeping. I burn small wood, and never load it and burn a "big" fire. It keeps the house plenty warm, and I can get it so I have to open windows if it is in the 30's outside, and my house is not overly insulated, and the windows are not great.

I'd say buy a stove sized for your space. You can build a hot fire if you want, or just keep it burning nicely if it works for you. I don't mind feeding it every hour or so. I lived 10 years with no other source of heat except my Jotul F118. I'm now in my late 50's and refuse to be a slave to my chainsaw, my splitting maul, my wood pile, and my wood stove ever again! Another great stove, by the way. I am a Jotul fan, through and through!

 

[peakbagger]

Yes, for sure. Modern EPA stoves are designed to burn clean or not well at all. When wood is heated, there are numerous intermediate reactions, but the big one generates Carbon Monoxide (CO), if it is mixed with oxygen at a hot enough temperature, it converts to CO2. Stoves with catalytic combustors can burn the CO at lower temps. For the non catalyst equipped stoves to burn wood completely to CO2 they need to get the heated oxygen molecules to be thoroughly mixed with cloud of CO and that requires a combination of turbulence and air distribution. This all needs to be done on the vast majority of stoves using the natural draft of a chimney through the stove. Make the stove and chimney too large to handle running it at high loads and when the stove is turned down, the stove has less draft to obtain the internal temps and turbulence required to burn the wood completely. A combustor drops the temp where the CO lights off so it can usually deal with being turned down more than non catalyst equipped stove. Further complicating things, is that water does not burn at these temperatures. Damp wood has liquid water in it and in order for it to go up the stack it has to turn to vapor and hat absorbs energy which drops combustion temps. Water Vapor also takes up a lot of volume so that reduces the draft in the chimney as part of the volume is taken up by water vapor.

Further complicating things is the heat demand is not always the same, sometimes its 40 degrees outside and sometimes its -10, so the stove is always having to be turned down. Most people want a stove designed for the worse case outdoor temps, so they tend to be oversized 90% of the time. They also want a stove that can run unattended for long periods without having to add wood. A basic box stove that was optimized to pass the EPA standards is not going to have much turn down and should be run at full load. More expensive stoves are hopefully designed better internally to handle turn down better and combustor equipped stoves are also going to be able to burn with more turn down but even those stove are going to have a tough time dealing with a poor chimney design and damp wood.

There is also thermal mass. of the stove and the room. If you are willing to build smaller fires more often just dont run it all the time during warmer days and brn smaller loads. Most stoves will retain coals for several hours, so if you keep some good kindling around it is not that hard to relight a stove.

One of my former professors was an advocate of owning two stoves, one for shoulder seasons and one for the coldest time of the year and swap them seasonally.

So if you want to get good turndown; buy a good stove sized to your heating demand, have dry wood, either kiln dried or wood you dried yourself to below 20% moisture (preferably lower), have a tall insulated stack sized for the stove with no bends or transitions (its going to need to be a minimum of 2 stories, preferably discharging above the highest point on the roof)

 

[KDubU]

Yes you can. It’s best to size the stove to your needs. The “go bigger is better” I don’t believe makes sense when considering a wood stove. Not saying you can’t go this path but consider:

- bigger stove requires larger hearth based on the footprint of stove and clearances
- bigger stove from the same manufacturer tends to be more expensive (why waste the money as the pipe and install will cost you)
- are you truly obtaining the efficiencies from a large stove you are half using, i.e. burning smaller fires ( this is above my smarts on stoves and there are plenty on here smart enough to confirm/deny this is applicable).

As for driving one out of the room or maybe even the house due to heat, it’s not fun. I would rather be a bit cool than overheated but that is my two cents.

 

[heat my feet]

There is also thermal mass. of the stove and the room. If you are willing to build smaller fires more often just dont run it all the time during warmer days and brn smaller loads. Most stoves will retain coals for several hours, so if you keep some good kindling around it is not that hard to relight a stove.

I agree! I usually always have coals remaining. I split a boatload of kindling ahead of time so I dont have to do it when it's cold and snowing outside. I try to have double the wood I need every year in my shed, so it will definitely be dry the following season. Small hot fires are the way to go. I barely see smoke from my chimney, and when I clean it in the spring there is hardly any creosote.

That being said, time to toss in a few more chunks before I head out!

 

[heat my feet]

One more thing. Between the f118 and the f100, I had a Vermont Castings intrepid. It had a cat, and a thermostatic damper on the rear. I hated it! There was no way to close the damper completely, and by the time I got it to "flame off", it was too hot. My F100, only has the damper in the front, a baffle above the fire box and the exit piping into the chimney. I love it! If I shut the damper all the way, I can pretty much choke the stove out. I hardly ever use it, except if it really cold when I go to bed, I shut it down to about 60% so I know I'll have a warm chimney and some coals in the morning. Most of the timeI leave it open and, once again, burn small hot fires.

 

[Todd]

How big of space are you wanting to install the Oslo in? The Oslo isn’t a large stove more medium sized with a 2.4 cu ft fire box. My F45 is just about the same size and it burns clean and efficient with half loads just fine. Nothing wrong with occasionally cracking a window if it gets a little warm.

 

[colin.p]

I live in a two story turn of the last century farm house, located in the coldest country in the world. For the last 16 years, I've heated with an oil furnace and a Jotul F3 CB. The little Jotul has paid for itself many times over, however with our miserable climate, it has struggled at times, requiring assistance from my oil furnace.

This year, what with the uncertainty of reliable oil/propane/electric supply and needing to rebuild the Jotul, I decided on getting a larger stove and use it as my main heating source. The Jotul has a 1CF firebox , while my new stove has over 3CF and for the first time, I now experience what wood heating really should be, while the oil furnace only turns on when I turn it on, mainly to warm up the dirt floor basement to keep the water pipes happy.

I can light a small fire (about the amount I would burn in the Jotul) and experience more heat from my new stove and boy oh boy, does she pump the heat out when fully loaded and it's friggin' cold outside.

I have since found that I much prefer having a larger stove than a "smaller" one as I can rely more on it's ability to heat when it gets really cold outside.

 

[brenndatomu]

I would lean toward a tad big rather than too small, but not too much...a stove that is way too big would be a real PITA!

 

[brenndatomu]

One of my former professors was an advocate of owning two stoves, one for shoulder seasons and one for the coldest time of the year and swap them seasonally.

We do that...have the Kuuma whole house furnace, and a Drolet 1400i in the LR fireplace, it works well for those cool days in the spring n fall when you just need a little heat...also, when it gets really cold (like we just had over Christmas) it works better to run them both together, than to run the bag off the Kuuma trying to keep up. Even a small fire in the 1400i provides enough extra boost to allow the furnace to be run in a more average manner (as far as load sizes and frequency)

 

[Hwkmn05]

I ve had oversized stoves the last 12 seasons. With a well insulated home of sprayed walls, it was very economical to heat. Unfortunately, it was unbearable and hard to control the comfort in our living/TV area most of the heating seasons and our usage went down. This year we moved the stove, still oversized, to an adjoining unheated insulated porch and with the use of a sliding door and fans, have been able to keep the temp comfortable in living area, 70-77, and perfect in the bedrooms, 66-72. Im glad I kept the oversize stove, but wish I had chosen an ideal area for it years ago.

 

[ohlongarmisle]

I have a friend who claims that bigger wood stoves require bigger fires to keep them running properly.

I am looking at an Jotul Oslo. The space it’s going in is rather small, but I just figure I can run a smaller fire.

I don’t want to be stuck in a room is overheated. Looking for your thoughts.

I have one of the largest stoves made,King Parlor, at times i don't need a full 4.5 cu feet of wood in it, as long as i can get the combustor activated usually takes 5 splits, i'm good to go for a stretch. Better to have and not need, than to need and not have, i wouldn't sweat it.

 

[begreen]

I have a friend who claims that bigger wood stoves require bigger fires to keep them running properly.

I am looking at an Jotul Oslo. The space it’s going in is rather small, but I just figure I can run a smaller fire.

I don’t want to be stuck in a room is overheated. Looking for your thoughts.

@jcbmv11 we need more specifics. All opinions will be speculation without some dimensions. An oversized stove can definitely overheat a space if there is nowhere else for the heat to go. If the fires are continually too small the stove is likely going to perform poorly.

How large is the area where the stove will be located? How open or closed off is it from the rest of the house? Is there a staircase or loft level where the heat can migrate upstairs? Can you post a rough sketch showing the floor plan and stove location?

 

[mdocod]

There are a lot of variables that factor into what an "oversized" stove is for a particular space.

The size of the stove, in and of itself, doesn't paint the complete picture. All we know at this point is how much fuel we can load into the stove.

Some stoves are light weight, some are heavy. All things being equal otherwise, a heavier stove will heat up and cool down slower. This spreads out the thermal output over time, which can make a larger stove more tolerable in a smaller space.

Some stoves are tuned for faster combustion, some are tuned for slower combustion. A big stove that can burn slow may actually be better in a small space than a small stove that can only burn fast.

Hard wood can be burned slower and lower than softwoods. A hardwood with 50% more BTU's in it, can be burned over about double the cycle time without the consequences of soft-woods burned that slow and low (a sooty mess), so if you have access to hardwood, the feasibility of low slow burning in a larger stove improves.

The Jotul F 500 V3 OSLO is a relatively heavy stove that combines secondary combustion with catalytic combustion which allows it to be turned down to lower burn rates than non-catalytic stoves of this size. This stoves has an EPA tested BTU range comparable to non-cat stoves of around 1.6 cubic foot, but will probably have near double the burn time on a load of fuel. I would expect these characteristics to make it fairly well suited to being an "oversized" stove in a smaller space. I think this stove could be fairly comfortable to live with in places that would normally be fitted with 1.2-1.9 cubic foot non-cat fireboxes.

The down-side to this stove for this application, is that, when turned down to a low burn rate, you won't get a traditional "fireplace view" of flames in the beautiful stove, rather, you'll get a river of flaming secondaries at the top of the box, followed by a pile of black wood chunks off-gassing through the combustor. If you want the ambiance of a flickering fire, you may be better served with a smaller stove that could be operated more "open."

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I would not advise intentionally burning small fires (small fuel loads) in a big stove, rather, select a stove that is capable of low burn rates from an appropriate fuel load for the stove. This will allow you to do proper stove startups with plenty of fuel feeding a hot fire when you're first settings things in motion, then choke it down to a slow burn rate after wards that will hold steady for many many hours.

Regular undersized fires could lead to more rapid formation of soot/creosote on the chimney system and/or even the cat. That said, it may be more feasible if you use thinner splits of hardwood, so that you're not sooting up the system with resin rich pine/fir/etc.