I have a brainstorm idea, dont hang me, just questions

[kennyp2339]

I was just thinking of an idea, sometimes especially with the newer epa stoves we have wood that's not so seasoned, sometimes we burn with wood that in the lower / mid 20% area and we're not getting the full amount of heat because the fire has to work through the moisture first. Or sometimes we get a super cold outbreak of cold and our stoves are burning a little cooler because they can keep up, I might have a simple solution but this will need some conversation by our valued membership.
I was thinking about how much heat comes through the large viewing glass in front of the stove, if the stove temps are running to cool from less than par wood or extreme cold, the open glass hurts operation by allowing additional heat through radiation to leave the firebox, what if there was some type of metal shudder that can be closed to block the window, do you think that would boost up the fire box temps enough to hit that crucial 500-650 deg stove top to have a clean full function burn, redirect more heat into the stove without over firing so the blower setup can make more convective heat?
I'm just wondering what you guys think, I know if I did that I would use some type of electric temp sensor alarm incase the stove went into the danger zone, but it seems like a fairly realistic idea that can help some people.

 

[begreen]

Maybe test your theory with some tin foil (covering the glass, not your head. ) Better yet, get some big rubbermaid containers and fill them up with splits kept indoors. That will dry them out quicker.

 

[WoodyIsGoody]

I was thinking about how much heat comes through the large viewing glass in front of the stove, if the stove temps are running to cool from less than par wood or extreme cold, the open glass hurts operation by allowing additional heat through radiation to leave the firebox, what if there was some type of metal shudder that can be closed to block the window, do you think that would boost up the fire box temps enough to hit that crucial 500-650 deg stove top to have a clean full function burn, redirect more heat into the stove without over firing so the blower setup can make more convective heat?

I'm interested in woodstove physics and design and recently have been reading up on high temperature materials. This is fascinating stuff and I don't think any stove manufacturers have taken stove design to the next level of optimization using current technology and knowledge. I'm thinking of stoves designed to create a secondary burn chamber that is more optimized than flat ceramic firebricks with secondary air jets that aresimply drilled or stamped holes. New designs could use things like cast ceramic secondary burn chambers with built in air jets optimized for secondary swirl. But there seems to be limited interest here for theoretical discussions of improved stove design (based on response rate and depth of previous discussions).

I'm just wondering what you guys think, I know if I did that I would use some type of electric temp sensor alarm incase the stove went into the danger zone, but it seems like a fairly realistic idea that can help some people.

The glass used in woodstoves is different from ordinary glass in that it is actually quite good at reflecting infra-red radiation back into the stove. Your idea might be more effective if the shutters were not metal but stove glass. Because the glass does get hot and radiate some heat into the room. But such a feature (whether metal or glass) would add considerable cost to the stove.

I think a domed top to the firebox interior, cast from refractory ceramic, would be more effective at increasing combustion chamber temperature during low burn by concentrating infra-red energy back to the center of the firebox. And it would need zero maintenance and last longer.

was just thinking of an idea, sometimes especially with the newer epa stoves we have wood that's not so seasoned, sometimes we burn with wood that in the lower / mid 20% area and we're not getting the full amount of heat because the fire has to work through the moisture first.

I'm all for increasing burn efficiency at lower burn rates, and while any design that achieves that goal would necessarily be better at burning half-seasoned wood, the fact remains, fully seasoned wood would still burn better and more efficiently and be easier/faster to do a cold start. So I see the answer to partially seasoned wood is to let is dry another season. I think wood-burning is both a right and a responsibility. If you're going to exercise that right, you have a responsibility to plan ahead.

But on the subject of using more refined designs to increase low burn rate efficiency, I think the reason manufacturers current designs are not more advanced is due to the fact that historically wood burning stove manufactures sprang up in low-tech welding shops. Many were in rural areas and it was a business that attracted bright people without much exposure to hard sciences and high technology. It's rooted in the industry. No doubt, with EPA regs, technology is becoming more and more a necessary part of the industry but change is often slow when coming from humble beginnings. The current manufacturers who are most successful didn't achieve that success by using high technology or over complicated designs. I do think that's beginning to change but change is often a slow process.

I think there is a huge opportunity available for any manufacturer who comes out with a simple but high quality woodstove with fully optimized firebox. I think a thermostatic control would be necessary to simultaneously achieve safety while still allowing a broad range of efficient and clean heat outputs.

 

[WoodyIsGoody]

Better yet, get some big rubbermaid containers and fill them up with splits kept indoors. That will dry them out quicker.

The Rubbermaid containers I've seen are not suitable for drying wood quickly. I imagine you are referring to a well-ventilated laundry basket type container?

 

[kennyp2339]

Maybe test your theory with some tin foil (covering the glass, not your head. ) Better yet, get some big rubbermaid containers and fill them up with splits kept indoors. That will dry them out quicker.

Crap, I got the foil application wrong again lol, one day I will be the hammer and not the nail, until then I'm glad your around.

 

[bholler]

I'm interested in woodstove physics and design and recently have been reading up on high temperature materials. This is fascinating stuff and I don't think any stove manufacturers have taken stove design to the next level of optimization using current technology and knowledge. I'm thinking of stoves designed to create a secondary burn chamber that is more optimized than flat ceramic firebricks with secondary air jets that aresimply drilled or stamped holes. New designs could use things like cast ceramic secondary burn chambers with built in air jets optimized for secondary swirl. But there seems to be limited interest here for theoretical discussions of improved stove design (based on response rate and depth of previous discussions).



The glass used in woodstoves is different from ordinary glass in that it is actually quite good at reflecting infra-red radiation back into the stove. Your idea might be more effective if the shutters were not metal but stove glass. Because the glass does get hot and radiate some heat into the room. But such a feature (whether metal or glass) would add considerable cost to the stove.

I think a domed top to the firebox interior, cast from refractory ceramic, would be more effective at increasing combustion chamber temperature during low burn by concentrating infra-red energy back to the center of the firebox. And it would need zero maintenance and last longer.



I'm all for increasing burn efficiency at lower burn rates, and while any design that achieves that goal would necessarily be better at burning half-seasoned wood, the fact remains, fully seasoned wood would still burn better and more efficiently and be easier/faster to do a cold start. So I see the answer to partially seasoned wood is to let is dry another season. I think wood-burning is both a right and a responsibility. If you're going to exercise that right, you have a responsibility to plan ahead.

But on the subject of using more refined designs to increase low burn rate efficiency, I think the reason manufacturers current designs are not more advanced is due to the fact that historically wood burning stove manufactures sprang up in low-tech welding shops. Many were in rural areas and it was a business that attracted bright people without much exposure to hard sciences and high technology. It's rooted in the industry. No doubt, with EPA regs, technology is becoming more and more a necessary part of the industry but change is often slow when coming from humble beginnings. The current manufacturers who are most successful didn't achieve that success by using high technology or over complicated designs. I do think that's beginning to change but change is often a slow process.

I think there is a huge opportunity available for any manufacturer who comes out with a simple but high quality woodstove with fully optimized firebox. I think a thermostatic control would be necessary to simultaneously achieve safety while still allowing a broad range of efficient and clean heat outputs.

There are and have been several stoves that use secondary combustion chambers like you describe. And yes they can work but they are harder to get to run properly. They are harder to maintain. And the parts are expensive.

 

[TedyOH]

I didn't know stoves, or the wood, burns cooler when it really cold out, why is this?

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[Rearscreen]

I was thinking about how much heat comes through the large viewing glass in front of the stove,

I think I saw a video on how to replace a Woodstock double pane glass and as I recall there is an inside and outside to reflect heat back in.

 

[bholler]

I didn't know stoves, or the wood, burns cooler when it really cold out, why is this?

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It does not at all

 

[begreen]

I think I saw a video on how to replace a Woodstock double pane glass and as I recall there is an inside and outside to reflect heat back in.

Some ceramic glass has a reflective infrared coating on one side.

 

[Michael Sean]

I'm interested in the reflective paints that are used in forges to increase efficiency and temps in the forge. If you can keep the firebox hotter at a lower burn rate you increase efficiency. This would also help the temp rise quicker on cold starts.

As Woodyisgoody said if you could also implement the swirl of secondary combustion air to throughly mix the exhaust gases to ensure that they are completely burning.

Im not sure if the reflective paint would work, that's just an idea. I think a lot of the stoves that are sold at the big box stores have a lot of room for impovement. I know a lot of money goes into the R&D but still they are produced to be cost effective.

 

[bholler]

You also have to look at the fact that the more heat you reflect back in the less heats your house. You need a balance. You can make a stove burn as efficiently as you want but if you dont transfer any heat to the house it doesnt do you any good.

 

[webby3650]

You also have to look at the fact that the more heat you reflect back in the less heats your house. You need a balance. You can make a stove burn as efficiently as you want but if you dont transfer any heat to the house it doesnt do you any good.

Kinda like a Hearthstone!

 

[Squirrel]

Just a thought.

How about adding a thin layer of insulating or soft firebrick behind or under your existing hard bricks? It would certainly raise your firebox temperatures. Bit of a pain to remove when you run into some good wood though!

 

[WoodyIsGoody]

You also have to look at the fact that the more heat you reflect back in the less heats your house. You need a balance. You can make a stove burn as efficiently as you want but if you dont transfer any heat to the house it doesnt do you any good.

A clean sheet design could still radiate just as much heat on high burn (slightly more due to refined design) but have a much larger range while being more efficient and cleaner when burning at low BTU's in the middle of the combustion chamber. It would have a light weight refractory ceramic domed central combustion chamber designed to reflect heat to the center of the firebox floor. An automatic (non-operated) bi-metallic thermostat would cause most or all the combusted gases to exit through the middle top of the dome at low firebox temperatures and straight into the stovepipe. At higher firebox temperatures, it would allow an increasing amount of the semi-combusted gases to spill under and around the domed firebox top where it could rise into a tertiary combustion chamber (just above and around the domed top of the firebox) where more pre-heated intake air would be introduced before exiting through a secondary path to the flue. At high burn rates this path would provide the same or greater peak heat output as current stove designs of similar size. The intake air outlets and shape of the firebox would be designed to create a tornado shaped circulation pattern. The automatic thermostat responding to firebox temperatures would prevent runaway fires by over-riding the primary (owner operated) thermostat. The primary thermostat would measure overall temperatures near the flue collar and control the overall intake air supply.

The development and testing of such a stove would be much easier/cheaper if servos, thermocouples and a microprocessor were used in development. Once proven, it may be possible to convert the design to entirely mechanical control using bi-metal actuators or other means.

The benefits extend well beyond a broader range of BTU outputs. Cold starts would be quicker and cleaner getting the stove into the efficient range using less of the firebox load. Less ash and unconsumed charcoal leftover and less pollution/more heat/efficiency at the end of the burn.

 

[webby3650]

A clean sheet design could still radiate just as much heat on high burn (slightly more due to refined design) but have a much larger range while being more efficient and cleaner when burning at low BTU's in the middle of the combustion chamber. It would have a light weight refractory ceramic domed central combustion chamber designed to reflect heat to the center of the firebox floor. An automatic (non-operated) bi-metallic thermostat would cause most or all the combusted gases to exit through the middle top of the dome at low firebox temperatures and straight into the stovepipe. At higher firebox temperatures, it would allow an increasing amount of the semi-combusted gases to spill under and around the domed firebox top where it could rise into a tertiary combustion chamber (just above and around the domed top of the firebox) where more pre-heated intake air would be introduced before exiting through a secondary path to the flue. At high burn rates this path would provide the same or greater peak heat output as current stove designs of similar size. The intake air outlets and shape of the firebox would be designed to create a tornado shaped circulation pattern. The automatic thermostat responding to firebox temperatures would prevent runaway fires by over-riding the primary (owner operated) thermostat. The primary thermostat would measure overall temperatures near the flue collar and control the overall intake air supply.

The development and testing of such a stove would be much easier/cheaper if servos, thermocouples and a microprocessor were used in development. Once proven, it may be possible to convert the design to entirely mechanical control using bi-metal actuators or other means.

The benefits extend well beyond a broader range of BTU outputs. Cold starts would be quicker and cleaner getting the stove into the efficient range using less of the firebox load. Less ash and unconsumed charcoal leftover and less pollution/more heat/efficiency at the end of the burn.

Sounds like you've got it all figured out.

All you need now is to drop a few million dollars to get this thing into production!

 

[Michael Sean]

You also have to look at the fact that the more heat you reflect back in the less heats your house. You need a balance. You can make a stove burn as efficiently as you want but if you dont transfer any heat to the house it doesnt do you any good.

I would say it depends on your situation. If you have a smaller new construction house that is well insulated and you want 10+ hour burn times with out having to open every window in your house, then it would be perfect. Yes you could buy a cat stove that would do the same thing, but not everybody likes/wants/ can afford a nice cat stove. By having a firebox that can retain/reflect heat more effectently without getting the rest of the stove crazy hot, you can have the bigger firebox and get the longer burn times that everybody is after.

 

[Fuut Master]

Kinda like a Hearthstone!

Ouch that hurt.

 

[NoGoodAtScreenNames]

How about blowing the secondary burn downward into a beautiful vortex of awesomeness?

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[HisTreeNut]

How about blowing the secondary burn downward into a beautiful vortex of awesomeness?

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That looks pretty interesting.

 

[bholler]

I would say it depends on your situation. If you have a smaller new construction house that is well insulated and you want 10+ hour burn times with out having to open every window in your house, then it would be perfect. Yes you could buy a cat stove that would do the same thing, but not everybody likes/wants/ can afford a nice cat stove. By having a firebox that can retain/reflect heat more effectently without getting the rest of the stove crazy hot, you can have the bigger firebox and get the longer burn times that everybody is after.

Regardless of your situation no matter how completely you burn the wood unless you transfer the heat from that combustion to the house your overall efficency is not going to be good. If you have a smaller well insulated home the right type of stove for you is a cat.

 

[Michael Sean]

Well since this particular subject is about ideas and brainstorming about how to make stoves run better. I wonder if replacing the ceramic boards on top of the secondary burn tubes with stainless steel sheets would help any? Certainly would be sturderier and would not break if accendently hit while loading the stove.

 

[bholler]

Well since this particular subject is about ideas and brainstorming about how to make stoves run better. I wonder if replacing the ceramic boards on top of the secondary burn tubes with stainless steel sheets would help any? Certainly would be sturderier and would not break if accendently hit while loading the stove.

There are plenty of companies that have done that. Some have had sucess others have had issues with warping. The fact is that baffle is most likely going to need replaced occasionally. Like the firebrick. It gets intense heat and does get hit occasionally.

 

[WoodyIsGoody]

Well since this particular subject is about ideas and brainstorming about how to make stoves run better. I wonder if replacing the ceramic boards on top of the secondary burn tubes with stainless steel sheets would help any? Certainly would be sturderier and would not break if accendently hit while loading the stove.

The ceramic fiber boards at the top of the firebox are designed as an insulated ceiling to create a very hot secondary burn area. Stainless steel would not provide the same level of insulation. Don't the secondary air tubes protect the ceramic fiber board from impact?

 

[WoodyIsGoody]

Regardless of your situation no matter how completely you burn the wood unless you transfer the heat from that combustion to the house your overall efficency is not going to be good.

True, the heat needs to be eventually transferred to the room to achieve efficient heating. How efficient the stove is at doing this can be measured by two things:

1) exhaust gas temperature
2) exhaust gas volume (velocity)

All heat that doesn't go up the flue ends up in the room, no matter how well insulated the various burn chambers are. The stove should be designed such that, once the exhaust gasses are completely combusted, they pass by enough radiating surfaces to cool them to the desired temperature. Too much cooling and the flue won't work properly, not enough and efficiency goes down.

You will note that in my proposed design, at low burn rates, the exhaust gasses have a more direct route to the chimney while, at higher burn rates, the gases are directed via a more circuitous route, exposing them to more surfaces so the heat can be transferred to the room via radiation or convection. In otherwords, a super-insulated combustion chamber is not incompatible with high final efficiencies. The goal is to separate the area of the stove where combustion happens from those areas of the stove where the heat is transfered to the room. Current designs do this but to a smaller degree. By separating these functions, a much larger BTU output range can be realized while simultaneously increasing overall efficiencies.

If you have a smaller well insulated home the right type of stove for you is a cat.

Yes, with currently available stoves. The design goal of the stove I'm proposing would bring long, clean and efficient burns to non-cat stoves.