I’m a welder in a large stainless steel shop, can get large pieces of sheet metal for scrap prices. 1/4 to 14 gauge. All the fittings and flanges one could imagine. And we can access rolls and breaks for home project use, as long as we get approval. I want to build a quality efficient boiler with steel cost not being the issue. Anyone have good plans
I made one out of a 250 gallon oil tank,
I opened one end and put a 22" diameter pipe 2" above the bottom, stopping 2" from the back and protruding 6" from the face.
I welded a 6" chimney protruding into the burn chamber to 4" from the bottom of the 22" burn box and made an "S" curve of chimney through the body of the oil tank. (This was a mistake as cleaning ash from the "S" pipe was a smoking nightmare! ( a better solution would be "T"'s protruding through the top and face, that could be opened to push a sweep through!))
I used #6 drag chain for hinges and had the entire face swing open, a weighted flapper to cut off air flow when a combustion blower stops, provides adequate control and a simple aquastat in a welded dry well cycling between 190 degrees and 200 degrees controlling the combustion fan.
Weld a dry well 12" from the top for the aquastat, and another for a thermometer (available from Mcmaster Carr.) a 1 1/2 inch bung ( just below the aquastat ) for supply to the pumps and a 1 1/2 inch at the bottom for return, and a ball valve for drainage.
Water level must be maintained above the dry well level or your controls are meaningless.
A J pipe inverted in the top for expansion and Bob's your uncle.
First the warnings;
THIS IS INTENDED TO BE AN OPEN SYSTEM NEVER REACHING BOILING TEMPERATURE. DON'T CLOSE IT UP AND DON'T APPROACH 212 DEGREES.
THIS SYSTEM MUST REMAIN OPEN TO THE ATMOSPHERE!!!
And the caveats;
The 22" burn chamber is marginal most commercial boilers use a firebox 3'x3' or larger.
My burn chamber was 52" long allowing 42" long pieces of wood, generaly what happened was 6" chunks piled solidly from chimney to face.
Don't skimp on quality piping to transfer your hot water to its destination, closed cell foam is a must, as ground water seeps in and conducts heat everywhere!
This held about 125 gallons of water many commercial boilers are much larger between 400 and 700 gallons.
Every time you add water you add oxygen, more oxygen more rust. Treat your water, and consider using glycol or even glycerin as a heat transfer fluid.
"Dudadiesel" (on Ebay) is the most economical source of heat exchangers I know of.
A simple ten plate heat exchanger gave me more domestic hot water than I could use.
Install a tempering valve at the top of your storage tank to keep from boiling your children alive, and scalding your grandma.
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