How big of a firebox should I upgrade to?
- Thread starter weee123
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil. -
Super Cedar firestarters 30% discount Use code Hearth2024 Click here
For longer burns go for a 3-3.5 cu ft stove. You can always build a smaller fire during milder weather. The large Drolets and the Englander 32-NC have big bellies.
Just placed an order for a 32-NC englander, should be here within a few weeks can’t wait.
Congratulations. You may need to change your handle from weee123 to Whee! 123.
Here she is in all her glory! Did the break in burns today and will install it sunday.
![[Hearth.com] How big of a firebox should I upgrade to?](https://www.hearth.com/talk/data/attachments/306/306569-0addcab68dbcc1a90da4bf2e7ffc1a5b.jpg?hash=NzqQ6bq33H "[Hearth.com] How big of a firebox should I upgrade to?")
![[Hearth.com] How big of a firebox should I upgrade to?](https://www.hearth.com/talk/data/attachments/306/306570-f0fef5a5e346fbd90d634b0f0549845d.jpg?hash=9z2mYQv3nq "[Hearth.com] How big of a firebox should I upgrade to?")
![[Hearth.com] How big of a firebox should I upgrade to?](https://www.hearth.com/talk/data/attachments/306/306571-d757e974f81f24d9f7681f44e0be56d2.jpg?hash=8ws8cVB5ie "[Hearth.com] How big of a firebox should I upgrade to?")
![[Hearth.com] How big of a firebox should I upgrade to?](https://www.hearth.com/talk/data/attachments/306/306572-ca074fa9c4ae8420549f32af7ed9afc2.jpg?hash=qJIDZy9b5k "[Hearth.com] How big of a firebox should I upgrade to?")
PAbeech
Burning Hunk
mdocod
Burning Hunk
A steel stove with secondary combustion, is by nature going to be optimized for shorter hotter burn cycles, and modern ones won't even allow shutting down to a smolder so any modern stove of similar combustion type, thermal mass, and thermal impedance, will have the same problems as your existing stove, and a larger version of such a thing will just result in too much heat during peak output.
If you want a longer burn cycle, but the same heat output over time, then you need a larger firebox that can manage a lower burn rate efficiently. The path to slower burn rates that are still clean is catalytic. Slower burn rates on a bigger box tends to be more thermally efficient so your wood will go further this way. (Bigger box, bigger heatsink!)
On top of that, it's worth considering the thermal mass of the system. More thermal mass can help smooth out the peaks and valleys of heating with wood, making a larger stove easier to live with. Heavy Soapstone and cast iron (or made from both) stoves are the go-to for this approach to stabilizing heat management.
Alternatively to thermal mass, is a combustion system with enough control that it can cleanly operate at low output levels. Blaze Kings are famous for this and can regulate efficiently across a wide range of output vs runtime. Think of a BK like a precision wood gasifier that smolders the wood then burns the wood gases off cleanly in a dedicated combustion chamber (the cat). A Princess 32 would be a lovely solution to your long-burn cycle goals.
I have been burning soft and VERY dry ponderosa pine. (like 8-9% moisture), so it wants to burn HOT and FAST. Despite the woods propensity to want to burn off fast, the Hearthstone Mansfield (new model with Hybrid combustion) that we are burning in does a pretty good job of chopping the peaks and valleys off the burn cycles, and extending the burn cycles out to 8-12 hours when loaded up and set in motion properly. (I have the same "standard" for "burn time." If the coals can be stirred and excited with the door open enough to be used to set off the next load). The stove stays warm for 12-16 hours after a load of wood (several hours after the fire/coals are basically dead) simply due to having a lot of thermal mass. I suspect that if I had access to some good hardwood this stove could probably produce burn cycles of 16-20+ hours? That might chase us out of the home the next day when the sun comes up! (we get day-time heat most days from a wall of south-facing windows. What we loose at night through them we probably make up for during the day here since it's sunny here most of the year.
-------------
Edit in:
Editing in a response to the purchase of the 32NC...
simple answer: that thing is going to be annoying as heck. Expect blazing hot chase-you-out fires that can't be throttled down very low. It's basically your old stove but twice the size. It's going to burn through wood fast, only mitigated by the opportunity to fit fatter pieces in it. That's the kind of stove you put in a workshop/garage for quickly bringing the temp of a cold, normally unheated space up to something comfortable fast and clean.
The heat output of your old stove was the right amount, what you needed was a bigger box with lower burn rates and/or more thermal mass, what you bought is just something with twice the size and twice the heat output. I don't think you're going to like it.
If you want a longer burn cycle, but the same heat output over time, then you need a larger firebox that can manage a lower burn rate efficiently. The path to slower burn rates that are still clean is catalytic. Slower burn rates on a bigger box tends to be more thermally efficient so your wood will go further this way. (Bigger box, bigger heatsink!)
On top of that, it's worth considering the thermal mass of the system. More thermal mass can help smooth out the peaks and valleys of heating with wood, making a larger stove easier to live with. Heavy Soapstone and cast iron (or made from both) stoves are the go-to for this approach to stabilizing heat management.
Alternatively to thermal mass, is a combustion system with enough control that it can cleanly operate at low output levels. Blaze Kings are famous for this and can regulate efficiently across a wide range of output vs runtime. Think of a BK like a precision wood gasifier that smolders the wood then burns the wood gases off cleanly in a dedicated combustion chamber (the cat). A Princess 32 would be a lovely solution to your long-burn cycle goals.
I have been burning soft and VERY dry ponderosa pine. (like 8-9% moisture), so it wants to burn HOT and FAST. Despite the woods propensity to want to burn off fast, the Hearthstone Mansfield (new model with Hybrid combustion) that we are burning in does a pretty good job of chopping the peaks and valleys off the burn cycles, and extending the burn cycles out to 8-12 hours when loaded up and set in motion properly. (I have the same "standard" for "burn time." If the coals can be stirred and excited with the door open enough to be used to set off the next load). The stove stays warm for 12-16 hours after a load of wood (several hours after the fire/coals are basically dead) simply due to having a lot of thermal mass. I suspect that if I had access to some good hardwood this stove could probably produce burn cycles of 16-20+ hours? That might chase us out of the home the next day when the sun comes up! (we get day-time heat most days from a wall of south-facing windows. What we loose at night through them we probably make up for during the day here since it's sunny here most of the year.
-------------
Edit in:
Editing in a response to the purchase of the 32NC...
simple answer: that thing is going to be annoying as heck. Expect blazing hot chase-you-out fires that can't be throttled down very low. It's basically your old stove but twice the size. It's going to burn through wood fast, only mitigated by the opportunity to fit fatter pieces in it. That's the kind of stove you put in a workshop/garage for quickly bringing the temp of a cold, normally unheated space up to something comfortable fast and clean.
The heat output of your old stove was the right amount, what you needed was a bigger box with lower burn rates and/or more thermal mass, what you bought is just something with twice the size and twice the heat output. I don't think you're going to like it.
Last edited:
Funny how this same stove has heated so many people's homes here on h.com successfully for years. If Brother Bart was still alive he'd be the first to call this BS. As far as mass, this is a 500+ pound stove, lots of mass.
I really appreciate the well thought out feedback and response but a catalytic stove was not even close to being in the budget unfortunately.
I also said in one of my later posts on this thread that the little Osburn couldn’t keep up the temps in my house at all once it got really cold out since it was unable to be run 24/7 anymore and maintain a temp. It was barely able to heat my living room and downstairs let alone my upstairs.
I heat my shop with an old barrel stove since it burns anything and everything I put in it including my oily shop towels. I wouldn’t put a modern woodstove in there because of that.
I also said in one of my later posts on this thread that the little Osburn couldn’t keep up the temps in my house at all once it got really cold out since it was unable to be run 24/7 anymore and maintain a temp. It was barely able to heat my living room and downstairs let alone my upstairs.
I heat my shop with an old barrel stove since it burns anything and everything I put in it including my oily shop towels. I wouldn’t put a modern woodstove in there because of that.
mdocod
Burning Hunk
Shipping weight is 440lbs... better than I thought. Most of the stoves in this class are under 400lbs shipping weight.
The 3.5 cubic foot firebox size also appears to be more exaggerated on this stove than most, EPA measured under 3 cubic foot...
Reviewing the EPA numbers it does look like this stove operates at a lower burn rate than I would have expected, though isn't particularly impressive for efficiency so part of reason the heat output looks lower is just that the efficiency isn't all that great to begin with. Most of the stoves with this sort of design (a baffled covered in secondary combustors) tend to be very hard to turn down below 20-30K BTU/hr rates, and will spike to 60K+ output. Looks like this one brakes from the norm among stoves like it. Maybe it will be usable in this application...
I expect the home described to need 10-20K BTU/hr on average most winter days. A lot of the steel stoves sold at big box stores like fleet farm, home depot, big r, are going to be overkill at their lowest burn rates for that heat demand.
mdocod
Burning Hunk
You're in New Jersey? How cold was it when the stove wasn't keeping up?
A 2.9 cubic foot stove heats 3500sq ft here down to around and sometimes below 0F before it starts needing assist from the HVAC. In that recent siberian arctic cold front we saw -18F as lows 2 nights in a row, with a day-time high between those lows o 0F. The furnace bridged the gap easily. By my calculation at those temps the house was demanding about 40K BTU/hr to maintain reasonable temps and the stove was doing about 3/4 of that. A 1600sq ft home should be more like 20K BTU/hr in the same conditions.
After reviewing some data on the Osburn 1600 vs the 32-NC, the heat output is more similar than I anticipated. Both measure similar peak thermal output (unexpectedly), so in theory the ~50% larger firebox might translate to ~50% longer burn cycles. It's unfortunate that the new stove, while burning cleaner, actually measures a fair bit lower thermal efficiency. I would expect that your wood consumption is about to go up by 50-60% (assuming you have time for a fixed number of reloads per day, and will be able to cram more than 50% more into a larger box because it's easier to fit more in there), but the heat going into the house is only going to increase by 40-50%.
Let us know how it works for you when set up. I hope the results are better than my napkin math and assumptions would indicate.
I have a split level house with my living room and kitchen half below grade. With my tstat set to heat my upstairs to 70 my downstairs will hang around 58-60 degrees because of rapid thermal loss through half the wall. It is difficult to overcome that and the Osburn is only able to do so while running 24/7 which I am unable to do now. My temps here were around -11 real feel last weekend and the osburn was barely able to heat the living room let alone the whole house. Even when it’s 20-30 it struggles off a cold start which is what it’s doing everyday now that it’s cold while I’m at work. My lower level walls consist of half block with drywall over it with no insulation and old insulation on the upper half.
I do not want a cat stove because I’m not spending more than $2k on a woodstove. A 40-50% increase in stove heat output and burn time is HUGE. The difference between 40-50% and 50-60% is damn close enough for me. I don’t understand why you think secondary reburn stoves are no good other than a shop stove. Thousands and thousands of people would strongly disagree with you. I wouldn’t even consider an epa stove for a shop heater with what I burn in my shop.
I do not want a cat stove because I’m not spending more than $2k on a woodstove. A 40-50% increase in stove heat output and burn time is HUGE. The difference between 40-50% and 50-60% is damn close enough for me. I don’t understand why you think secondary reburn stoves are no good other than a shop stove. Thousands and thousands of people would strongly disagree with you. I wouldn’t even consider an epa stove for a shop heater with what I burn in my shop.
mdocod
Burning Hunk
-11 "real feel" === wind chill?
The wind chill here was -50F during that arctic blast we had a couple weeks back.
Sounds like your home is requiring huge BTU input to maintain comfortable living temps, that's not a good position to be in long term. I believe that you would have been better served to take the money spent on the wood stove, and instead spent it on finding a way to insulate and seal up some of the worst offending parts of the home. If you have drywall right over concrete blocks in the basement, then that's going to be painful as the ground temps drop through the season. I can only imagine how cold that room must be in February.
I have nothing against non-cat stoves. The elegance and simplicity of a secondary-only combustion system that can hit low emissions is awesome! I also like Rocket Stoves, and any form of combustion that is thorough and efficient. However, your short burn cycle experience Osburn 1600 experience is the experience I have seen with most of these types of stoves if they have been designed with a minimum burn rate that attempts to keep those secondaries active through as much of the burn cycle as possible. Hitting the EPA emissions requirements with secondary-only combustion is very do-able but usually requires a higher minimum burn rate because secondary combustion ignition temps are much higher than the temps required to burn off gases in the presence of a catalyst.
The 32-NC appears at first glance to be like a US/China Stove Company US3200E and it's many variants sold under many names. The fireboxes look extraordinarily similar. I have used a US2500E which is built basically the same way but just slightly smaller and it burns through wood fast and hot just like your Osburn 1600. According to EPA testing the US3200E also burns very hot and fast. When looking at the 32-NC there isn't much reason to believe it would be meaningfully different, however, EPA test results do show a lower BTU output range, higher emissions and slightly lower efficiency, suggesting that the combustion system has been tuned a bit different to try to force a secondary stove to run longer at lower output while still being within the EPA limits. It may work very well for you in this application!
Secondary combustion stoves like the US3200E are great for a shop stove as then you can burn off all those filthy things without a cat to plug up. Turn the oily rag into heat rather than black smoke for the neighbors to breath. The BTU output from these things, especially when equipped with a blower, is truly furnace territory (peaking at ~60-70K BTU output!!) and is ideal for heating up a cold shop quickly! Stoves like this tend to be relatively inexpensive, ~$1000-1500 give or take depending on sales/deals. Most of them aren't built to last for daily burning for decades, but for a shop that might get a couple burn cycles a week.. not bad.
With that lower level sucking up heat, I don't think you'll have to worry too much about roasting yourself out. It also sounds like you are burning light wood; With denser wood, the first part of the burn will be more under control. When you're deeper into the burn with a full load, of course, there's more gassing regardless of what type of wood you have in there.
It sounds like you are gone for a while during the day, so if it roasts a bit down there when loaded full, that'll keep it warm until you get home. Then in the evening you can burn smaller loads for less output, if need be.
Maybe the block-wall lower level in the ground hurts you in the winter, but probably helps in the summer with AC costs. 🥹
It didn't seem to me that mdoc was saying that secondary stoves are only good for a shop, I think he was just saying they operate within a higher heat range.
It was an off-base and incorrect statement as are those that followed. BrotherBart put in the 30-NC in 2006? and heated his home with it until he passed this year. It's a very reliable performer. Mrs. Krabapple followed suit and put it in her old NC cabin a couple of years afterward. She still uses it as her primary source of heat. These are just 2 examples out of the hundreds reported here. Englander made a great value stove with this model.
The 30NC and the 32NC are totally US made in Virginia. It has been an exceptionally clean burner from the get-go and has a great track record as a 24/7 burner.
Last edited:
Dude, you are spouting a bunch of crap that you know little about.
Uh-oh, appears that begreen has been tipping a couple back to welcome in the new year, and is getting a bit feisty!😯😉
Last edited:
Pontificating posts that spout misinformation are neither helpful or welcome. The suggestion of tossing oily rags into a stove is just wrong. I get a bit peeved when constantly having to correct this BS instead of spending that time helping people that need it.
Great word. That's how I describe Jay Bilas doing color for college basketball. I mute games he does.
Well, since the OP is already burning the oily rags, I think it would be better to burn them in a secondary stove to catch more pollutants, instead of in an oil-drum rig. 😏
Point taken. And just let me say here, you do a great job, and help a lot of people get what they need from their stoves. Not to mention, you've probably saved a few lives along the way! 👍
Happy new year, everyone! 🤗
Similar threads
- Locked