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1

General Outdoor Furnace Discussion / insurance company wont insure with outdoor boiler

« on: June 20, 2008, 07:06:54 PM »

called my insurance company (one beacon) to get the minimum distance they wanted an owb located from any buildings and they said that they would not insure the home for anything associated or caused by the owb no matter where it was located. will be looking for a new carrier. any one else check on this or have a problem?
steve

2

General Outdoor Furnace Discussion / Re: How to determine how many BTU I need

« on: June 19, 2008, 04:57:52 AM »

Have not really started looking "seriously" at any one unit, but it sems I need to know what my btu needs are to match up against the proper unit? We have apprx. 1700 sq ft of living area and around 30% of it is newly constructed that is very well insulated. The only mention on my present oil boiler of anything btu shows Water MBTU 125.2/hr.  Not sure what that means but this boiler provides plenty of heat and hot water for our needs.

not sure but i think your boiler is 125200 btu. if it runs at 92% efficency, that would be 125200 X.92 = 115184btu output.
OUTPUT efficiancy for owbs vary widely depending upon wood moisture content, heat loss from the shell and piping, how well the boiler transfers heat from the fire to the water and how long the fire idles (smokes) without calling for heat.
some say as low as 30% for a poorly designed and poorly operated boiler.
add to that the many different opinions of the people youre going to talk to and as far as i can see, its a crap shoot!
check out these guys; http://www.hearth.com/econtent/index.php/forums/
they tend to lean toward the new gasifiers with storage but there are some really good boiler people there that will help you

steve

3

Home Made / Re: convert

« on: June 18, 2008, 10:45:33 AM »

steve..in the photo i posted earlier inthis thred of my "now" stove..it is infact a 36inch pipe inside a 42 inch pipe filled with water..it works well but i think the water cooled jacket in fact cools the gasses too quickly and a lot of potential heat is going up the stack

and that is why the owb as they have been designed in the past, are so smoky and ineffecient.
 i dont know exactly how the new gassifier boilers work since i have just begun to research and look at them.
 i dont think it makes any difference where you get the high temperatires that burns the wood gasses whether it is in the actual firebox or in a secondary chamber. just as long as you reach those 1500-2000 degree temps and then send them into a heat exchanger to extract the heat.
 maybe one of the gassifier gurus could chime in here and do some splainin to us.

4

Home Made / Re: convert

« on: June 18, 2008, 05:17:52 AM »

 it would be a lot of work to build the stove and have the firebox disintegrate. there isnt much heat transference from the inner pipe to the fire brick like there would be if it was air cooled or water cooled so i suspect that heat would build up to the point that the inner pipe would fail.
 im not a big fan of using refractory in the firebox either simply because i want to be able to throw the wood in and not have to worry about breaking it.
 im thinking that a water jacketed firebox might be the way to go and try to make the wood gasses burn hotter in another refractory lined chamber. then send the super hot burning gasses on to the heat exchanger.
 as to the secondary air, it all depends what you have for a chimney draft to pull the air in.
 
 i guess im like you in that im just in the planning stages right now and will consider all suggestions.

steve

5

Home Made / Re: convert

« on: June 17, 2008, 05:27:22 AM »

very cool, did you build it?

yes double..i built it...i  am planning on  another one in a  year  when i retire...i have  aquired another property and i want to build  one  with  a  (i have a tank allready) 1200 gallon  tank..i am hoping to  fire it  one time a day at most and have it  keep the things near  60 when i am there and  above  freezing  while i am away .....im not  much on  making  refractry so i am thinking of  a 36 inch pipe inside a 42 inch pipe filled  with fire brick between them...i hope  to achieve  very high  temps  burning  this  way....then have  the  heat move  out  the  chimey into a second  barrel that will have  tubes  (big  enough i can brush them) for  the  heat  to go  through and  have them surrounded by  water...then circulate the water  through my 1200 gallon tank untill the  set  temp is  achieved

you think this  may work/..i am looking for all kinds of input..then i  can have way  more  ideas  to contemplate on

 if your inner 36"pipe is insulated from the outer 42" pipe with firebrick, wont it get hot enough to melt or did i misunderstand your plan?
 also, when you go from the burn chamber to the heat exchanger, you might think about putting a secondary air inlet in order to give the gasses an additional chance to burn befor the exchanger cools them.

steve