sdkubota
Platinum Member
I used to have an Ashley woodstove and it is the most efficient wood stove made. It could easily hold a fire all night when temps were below zero.
Most efficient way to burn wood
- Thread starter arrow
- Start date
- Views: 14508
Burning your wood efficiently means a hot fire with the proper amount of combustion air. This likely means you will need a heat storage system and burns that are are designed for your situation.
Don't confuse the outside boilers that are loaded and left with less than sufficient combustion air as being efficient.
Any combustion system that requires cutting back on the proper amount of air to regulate heat is not efficient.
I agree fully. The "stoves" (if you want to call them that) that seem the most efficient are the one's that burn hot but retain the heat energy to give up later. They also weigh around 6000#. I also agree with the house being designed around the stove. Site orientation for solar gain, insulation and internal exhaust seem to be critical. I am also wondering about chimney design. Mass stoves have a long exhaust path extracting as much heat out of the exhaust as possible. Instead of creating this "mass" with the stove design which takes up a lot of floor space, why couldn't one create the mass with the internal chimney? The key here I believe is not to allow the exhaust gases to directly exit out the chimney but instead recirculate before expulsion. Draft might be tricky and I cannot picture this with a 15' tall chimney. With all the right combo's, one may need but a cord of wood all winter which I also cannot comprehend at this moment if wood is the main heat source for 7 months. This floor plan I'm looking at is 54'x32' which is only about a 1700 sq ft house. I love wood furnaces for their ability to convey radiant heat but as someone said, might be overkill.
Dave remember back in the 80's when solar houses made a big push? There were some windows that had the capability of having insulation blown into their air spaces at night and then this insulation would be sucked back out for daytime. All worked well as long as you had power.
clemsonfor
Super Member
Any combustion system that requires cutting back on the proper amount of air to regulate heat is not efficient.
NOT true this is why i suggested a CAT stove. You basically cut the air back till it smolders, no visible flame on the wood. You will get secondaries that float around at the top of the firebox buring the gasses inside before the rest goes through the CATs to totally combust. If you have good DRY wood and healthy cats and know what your doing you better have that blower on high to get that heat out cause your CAT temps will soar, if i dont cut my air back enough fast enough you will aee 1800F easy on the CAT probe. there designed to burn with low air and do it with ZERO smoke out of the chimney.
As has been commented, a wood boiler may be overkill for you, unless you are planning other buildings.
If you do end up considering boilers, check out Portage and Main Boilers:
Outdoor Water Furnaces | Boilers | Outdoor Boilers | Alternative Heating
I don't have one, but talked with their local rep, at the Farm Show in Toronto last month. Simple, very well thought out designs, easy to clean.
They have regular outdoor wood boilers, and well as the high efficiency gasifiers.
If you, or anybody you know, have been to Manitoba in the winter..... they know cold.
Rgds, D.
If you do end up considering boilers, check out Portage and Main Boilers:
Outdoor Water Furnaces | Boilers | Outdoor Boilers | Alternative Heating
I don't have one, but talked with their local rep, at the Farm Show in Toronto last month. Simple, very well thought out designs, easy to clean.
They have regular outdoor wood boilers, and well as the high efficiency gasifiers.
If you, or anybody you know, have been to Manitoba in the winter..... they know cold.
Rgds, D.
deezler
Elite Member
- Joined
- Jan 30, 2012
- Messages
- 3,659
- Location
- Southeast MI
- Tractor
- Cub Cadet 7305, Kioti CK3510seh TLB
This is a great thread. I'm really glad everyone took it to a place of complete home efficiency and not just the woodstove itself.
It seems like some people have a minor disconnect between absolute wood-burning efficiency and the efficiency of their overall wood-burning process. As already noted, most efficiency wood burning needs to be HOT (and thus, usually a fast burn). Do this in an open fireplace and most heat goes out the chimney. Do it in a cast iron stove, and your room will get boiling hot with a "peaky" temperature curve. A soapstone stove is better, since it can absorb more heat and slowly radiate it back out in to the room/house.
The more mass around your burn-box, the better! I hope to build a massive masonry heater in the center of my new home. Burn just one or two short hot fires per day, and the mass of the stove keeps the house at a nice even temperature.
The other thing worth mentioning is that a HOT burn is also a CLEAN burn, emissions of particulates and noxious gasses are much lower when everything has combusted fully.
A lot of people are suggesting me to go with an outdoor wood burner / boiler. To me (note, I acknowledge my limited familiarity) those things are junk. Adjusting them down to a slow burn means inefficient burning, tons of pollution and smoke, heat losses in the burner/pipes and then furnace ducts, and then you have to trudge outside to re-fill it? Not for me.
It seems like some people have a minor disconnect between absolute wood-burning efficiency and the efficiency of their overall wood-burning process. As already noted, most efficiency wood burning needs to be HOT (and thus, usually a fast burn). Do this in an open fireplace and most heat goes out the chimney. Do it in a cast iron stove, and your room will get boiling hot with a "peaky" temperature curve. A soapstone stove is better, since it can absorb more heat and slowly radiate it back out in to the room/house.
The more mass around your burn-box, the better! I hope to build a massive masonry heater in the center of my new home. Burn just one or two short hot fires per day, and the mass of the stove keeps the house at a nice even temperature.
The other thing worth mentioning is that a HOT burn is also a CLEAN burn, emissions of particulates and noxious gasses are much lower when everything has combusted fully.
A lot of people are suggesting me to go with an outdoor wood burner / boiler. To me (note, I acknowledge my limited familiarity) those things are junk. Adjusting them down to a slow burn means inefficient burning, tons of pollution and smoke, heat losses in the burner/pipes and then furnace ducts, and then you have to trudge outside to re-fill it? Not for me.
Well, this is true if you do not have a cat. Having one certainly changes this as a not so absolute axiom as it applies to wood stoves anyway. Cats have been around for a long time. I remember the retrofit ones that you could put into any wood stove. I do not know about todays cat technology but back then they were considered a pain to keep at their utmost efficiency and replacement was not cheap at $150 a pop. If they lasted even 5 years and saved one that much wood, its a small trade off. Actually, I have no idea how long they last in a wood stove today. I for one and at this point am not discounting their use for my purpose. Just have to become less ignorant of what they are today.
I think one of their main advantages is to heat multi buildings at one station. The most efficient ones use maybe a little bit more wood as a wood stove sq footage ratio wise. The not so efficient ones can use double the wood. Other advantages is they are cleaner for the house environs in not only keeping the wood mess outside, but also not breathing in the particulate matter of a wood stove inside the house.
dmccarty
Super Star Member
Designing and building a house is all about compromises even if you have Bill Gate's money. You will have to compromise less if you have Bill's money but compromise you will. And I am not really talking about what the wifey wants or does not want.
When I designed our house I spent years, and I do mean years, working through ideas for the house and money is a big factor since I do not have Bill's money.
Our first house designs were two stories to maximize solar heat gain. Passive design is easy if you can orient the house to the south. It does not cost much to do either. Our biggest expense with a passive design was the roof over hangs which are calculated from the house location and the bottom of the window. I think our overhangs are 28 or 32 inches, can't remember any more, :laughing: and the larger overhangs keep rain water off the walls and allow me to walk around outside in the rain without getting wet depending on the wind.
Anyhow, the two story designs were too expensive so we put everything on one floor which decreased the solar heat gain but so be it. We knew we wanted a colored concrete slab because it is easy to clean, it is cheap, and it provides a wee bit of mass for solar heat gain.
We looked at the large mass fireplaces but the cost was too much so we put in a hearth in the living room to hold a wood burning stove. The stove is not a catalyst and is supposed to heat either 1800 or 2200 sf. Our house is 2425 sf but we have 10 foot ceilings, another energy related design point, with an open floor plan and that wood stove heats the house well 95% of the time. The other 5% is when the temps drop in the teens or single digits and the highs are below freezing. Then the stove struggles to heat the house. When I say heat the house, I mean keep the living room at 80-82 where the wifey likes it. Away from the stove, the house is cooler and on cold days that means about 10 degrees cooler than the living room. With more moderate outside temperatures the difference between the living room and the bedrooms might be 5 degrees.The fireplace sits in a corner on a brick and marble hearth. The walls behind the stove are brick that are exposed in the rooms on the other side of the walls. The fire heats up the concrete floor but also the brick wall and both hold and radiate the heat. The brick walls also negated any concern with the distance from the stove to combustible materials. Mass is a compromise though. It works both ways. Mass holds temperature which can be good or bad. In the winter, if we leave for a few days the slab will be cold and take longer to heat back up. The same is true during the summer. If the slab heats up the AC has to deal with it. In the summer, if the humidity and heat is not bad, we will open the windows a bit at night to cold sink that slab which often prevents the AC from turning on until lunch time or later.
A concrete slab SCREAMS for radiant heat. The plan was to put in radiant heat with solar collectors. Then reality hit, meaning budget, aka money. The bottom line for us in my area in NC, radiant heating along with a wood stove, AND HVAC did not make money sense. Do we really need three active ways to heat the house?
No. And radiant was going to be around $10K. We made the right decision but on those 5% days when it is really cold outside I starting rethinking the decision. :laughing::laughing::laughing:Up NAWTH, this would be a completely different decision. I would think radiant heat would make money sense but us it did and does not make money sense.
We also looked at the expensive wood burning systems that burn quick and efficiently and store the heat in water. By the time, I heard about these systems it was too late since our floor plan was finalized. The problem we had with these systems, besides cost, was we had no space to for a huge tub of water to store heat. It would have required a redesign of the house to add the floor space and the cost of the floor space alone would have been very problematic budget wise.
We have huge holes in our walls called windows.
Each bedroom has one window that is 8'x6' so we can see outside. This is good but from an heating/cooling perspective those windows stink. We also have 10 foot tall ceiling which stink from a heating perspective since heat rises. We have these tall ceilings to maximize the window sizes and door sizes. We have eight foot tall doors. All of this balanced out design wise believe it or not. The tall ceilings are not great in the winter but they sure are in the summer. I wanted 12 foot ceilings but that was going to cost too much and I don't think it worked out well design wise. Old southern houses had 12, 14, 16, or even taller ceilings to get the heat away from people. There are old building in our town that have at least 16 foot tall ceilings. These tall ceiling work which is one reason we can keep our house a bit hotter than average. The windows do help cool the house if the humidity is not too bad. We made a series of compromises regarding size and number of windows and ceiling height vs heating and cooling. I think we made the right decisions.If we were in a colder climate, I would suspect we would have shrunk the window sizes and number and maybe lowered the ceiling height which would make heating the house much more efficient. Almost certainly, radiant flooring would have been used too. While our house uses passive solar it is not one of these houses that looks like it has passive solar design.
One of our concerns was heating the house, and one option we thought about at design time, was adding a second stove to the other side of the house. We could do this but I doubt we ever well since the stove we have works well.
Later,
Dan
GBOUTDOORS
Silver Member
We built our home in 2009 slab on grade then buried the front half so we could have a walk out finished basement. The lower back walls are concrete half way up then wood the rest of the foundation walls are full concrete 12" thick. The house was designed as a one floor two bedroom open floor plan ranch with 1442 sq. feet. In Mass. with our building codes you must us 2x6 construction to pass energy code, also r38 roof and r30 floor insulation. I did not insl. the floor as we planned to heat with wood from the walkout basement that way the heat radiates to the main floor. The first stove we had was my Dads Fisher from 1978 or so. It worked well but burned enough wood to heat two homes and we had to feed it all the time. This past fall we bought a Harman tl300 and retired the fisher to the barn we put up this fall. With the new stove we heated the house all this winter loading it at 5:30 in the morning then again at 4:30 in the afternoon. With the stove in the lower level it heats up the concrete floor and the walls and they give off heat well after the stove temp. has gone down. So far we have used 1 1/2 cords that's one third of what we were using in the old stove. I have propane as our backup heat and put in a Reni on demand water heater that works great . We bought 22 acres of mixed woodlands so we have all the wood in the backyard we will ever need. Good luck with your new home and have fun with the planning and building of it as Jane and I did. By the way arrow we are in Fairhaven Mass. So the weather here is close to yours. And you do not have to go with a cat. To get the afterburn as the Harman stoves do this with a reburn system as do some of the other top brand stoves. This system has worked great so far for us.
Last edited: