old wood burning stove use

[retire2$]

What about this idea or do you have any suggestions?

I have an old metal plate wood burning stove that is approximately 2 ft wide by 3 ft deep and 3 feet high. I was thinking of welding metal around the stove leaving a space in between in which an antifreeze solution would be stored. On the outside of the metal covering I would add insulation and then some sheet metal over that to protect the insulation from the elements. A minature version of an outside wood furnace with a few differences. The water volume would be minimal - just enough to fill the water jacket, the lines, the baseboard heater and a small resevoir to drain back the water from the baseboard I would only burn small hot fires to heat the water and then by way of insulated pex tubing run the water through a hot water baseboard then to the pump and back to the woodstove. The pump would be thermostatically controlled by the water temperature. What other safety features would you incorporate? What problems do you see with this system and what would you suggest to correct the problems.

This set up would not be designed to heat a house only to add a little supplemental heat in the evening while we are home.

Thanks in advance for any and all replies.

[Michael Kawalek]

Sounds like a disaster waiting to happen! The thermocycler design is a proven way to heat water, that was done in tens of thousands of homes around the turn of the last century. Basicly, you run a stainless steel water pipe through the inside of your stove. The pipes/tank are positioned so that hot water raises and goes into the top of the tank. Cooler water flows out the bottom of the tank to take it's place. The longer the stove burns, the hotter the water becomes. There was a post last week where some Mormans in Utah set up their cabin that way.

[Freeholder]

It would be safer, easier, and IMO more effective to just enclose the stove in some mass. You could build a brick surround up against the stove, or a cob one (cob is adobe -- you can google it if you need more info). Better yet, look into building a rocket stove. There's information on-line about them, or go to Paul Wheaton's Permaculture forum (he's a member here).

Kathleen

[ronbre]

NO DO NOT DO THAT !! If you want to heat the water with the antifreeze solution the best way is to run good quality pipes through the stove at the TOP..with the solution ..that is how our wood burning outdoor stove works..not water in a jacket around the firebox ! You will immediately have a boil over and ruin the entire area the woodburning stove is in..steam, hot steam spraying all over..trust me..you gotta know what you are doing to install a wood burning with circulating antifreeze.

before we had a boile over thermostate in our stove we had a dangerous boilover..and husband was nearly scalded..we immediately got the boil over unit installed..

then when the power went out one time and the pump was not circulating the water to cool it..we also had another dangerous boil over..that is why we are frantically trying to find a good generator before that happens this year..power outages can quickly cause a boil over..with very little heat left inside the stove !!

it can take two to three days of no fire for the stove to be safe enough to turn the pump off and not have a boil over

[solidwoods]

Put the stove outside, away from the house.

Black steel pipe inside the stove to run water through.
You can also make a water heat exchanger chimney to get more hot water.
The system must be open to the atmosphere or you will make steam pressure, also water expands when heated and would make pressure.
You have to make an open system, pressurized is dangerous unless a proven proper design construction is made.

The water jacket design is good though because it helps the fire box to not burn out, but pipes inside is allot easier.

Sounds like you have metal fabrication ability so maybe just make a jacketed heater from scratch. Propane tanks are a good source for materials (initial cutting must be done right though).

Chip feeders are a very nice addition also if you have a chip source.

If you have a large need for heat and an easy wood source, wood fired water heater can make you allot of $.
jim

[retire2$]

Thank you for your suggestions so far.

I would like to add some further clarification and restrictions that I have to deal with. My intention is to make this a portable unit. I would build a metal trailer with iron or removable wheels to put the stove on. During the winter the stove would be rolled to approximatley 12 feet of the house to supply the heat. In the summer it would be moved away from the house. Since I will need to insulate the stove from the outside weather I figured that putting a water jacket around the stove would be the easiest way to be able to insulate. The outside metal wall would not get so hot that the styrofoam insulation would ignite. This setup would also allow the largest surface area for the water to absorb the heat. I figured if I put the pipe inside the stove I would diminish the size of the firebox and I wasn't sure if there would be enough surface area to heat up the water. I also would still be faced with trying to insulate the outside of the stove. I will need some more suggestions to be able to pump the water through the system without building up pressure but still allow the baseboard heater to drain down when the fire goes out. I want this to be a drain down system so that I will not take heat away from the house when the system cools down. Power failure would not be a concern because I will only use this as supplemental heat while we are home. If the power went out I could go out and put the fire out by smothering with ashes or sand. I do not want to use forced air because the unit will be portable and I don't want to put a large hole in the wall to accomodate the piping.

Please keep your suggestions coming and if you can help me with the insulation and pressure issue I would greatly appreciate that also.

[rambler]

Oh, you didn't say it was an outdoor design. I was really afraid for your safety! Was sounding very bad!

Regular antifreeze doesn't work for long in a heating system - you need special stuff. Costs more. I won't get into the technical details - it just is that way.

You _must_ have an expansion chamber (air tank) and a pressure relief valve. Or you have a bomb. This takes a little planning. Each design needs a little different detail, so don't go by what you just hear here. Most outdoor stoves are actually open air designs with no pressure - but if you pump into the house, you end up with some section that is enclosed/ pressurized/ needs relief & expansion.

It might be much easier to start with 2 tanks, one a little bigger than the other, and set one in the endwall of the other. An exsisting wood stove does not lend itself well to the types of modifications you want to do.

By the time you are done with all the stuff you need to do to make it a proper thing, it might not be too difficult to buy an outdoor boiler.

--->Paul

[retire2$]

Thanks for responding.

Based on your comments from this forum and the Shop Talk forum here is my new game plan. I will put a metal jacket around and on top of the woodstove and fill with the antifreeze solution. I will put a 6 inch high fill tube on top of the jacket. This tube will be uncapped so I shouldn't have to worry about a pressure build up. The antifreeze solution will feed from the bottom of the water jacket and return to the top of the jacket. The outside of the metal jacket should be cool enough that I can put foam insulation on it without worrying about it igniting. (The water jacket is the only way I can come up with so that I can insulate the stove from the outside air temperature without the possibility of the foam insulation catching on fire). A sheet metal covering over the foam insulation should protect it from the outside elements. I can control the temperature of the water by the amount of wood I burn. I plan on putting the pump inside the house and have it operate off a temperature switch.

Anyone have any ideas as to how I can plumb the system so that when the pump shuts off the water in the baseboard will drain out of the baseboard into a resevoir of some sort. My thinking is that when the pump shuts off or the system is not being used that the heat inside the house will be absrobed and transferred to the outside and I will have a heat loss from the house.

What do you all think of this new plan?

Thanks in advance for any and all replies.

[Wis Bang]

We used an skid mounted oil fired boiler designed to heat thermal oil and circulate it at 400 degrees to heat asphault storage tanks and adopted it to circulate antifreeze [ethylene glycol] via a pipeline to heat railroad tank cars to maintain around 120 degrees.

The system had a vertical column on the return side that was topped w/ a small [250 gal] cylindrical tank. The system was filled by pumping the EG solution into this tank which also served as a purge & expansion tank. The unit was mounted inside a 45' van trailer and the purge tank set on the trailer roof.

Since we had to add and remove fluid as the railcars came and left we placed an additional 1000 gal tank on the ground and plumbed the overflow from the overhead purge tank down to the additional tank. When a railcar was empty we would shut the boiler down and purge the railcar heating coils w/ compressed air through the return pipeline pushing the EG back and up into the purge tank [with the valve between the return and boiler closed] where the excess could overflow to the storage tank.

We had an additional pump on the storage tank to pump fluid back into the feed side to fill the new railcars. When the railcars were drained/filled, all the valves were opened and the purge tank was free to overflow back to the storage tank after equalizing the fluid level in the system.

The original design was meant to operate w/ the purge tank 1/4 - 1/2 full and it had a top vent/overflow to relieve any pressure buildup/overflow. We plugged this w/ an expanding plug and used a threaded port 3/4ths up the side of the expansion tank for our overflow that was plumbed back to our ground level holding tank.

The return pipe entered the side of the column w/ a 'T' and the bottom of the column was the boiler inlet so any trapped air would go up into the purge tank. A sililar setup w/ an overflow plumbed back down to the ground so any overflow/boilover wouldn't spray all around would work for you.