Wood Stove and Boiler Tubes

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I have a Coal/Wood stove from the mid-70's that isn't really efficient in the sense of wood put in verses what heat goes up the chimney.I'm toying with the idea of hole sawing parallel holes in the front and back to slide 2" pipe in, then welding the pipes front and back.This would allow the flames/heat to envelope them before going up the chimney.Connecting them to a fan in the rear would allow heat to blow out the front.I guess my question is how do they compensate for tube expansion in a Steam boiler?Or is it the water envelope that keeps the tubes from growing?All I have figured out for sure is that the tubes will grow, maybe welding only at the rear?OR will the air going through them mitigate the Thermal growth?
Reply:do you have a damper in the chimney pipe? that will hold a lot of the heat in.Lincoln 225 ac (my first machine)farmhand 115vac 70amp mig/fc toymiller aead 200le (my main machine)
Reply:It has a damper inside the stove.Its just that it is a brick lined iron box with minimal baffling in it.I've even thought of putting a sheet metal envelope on the back and blowing air through that.The heat exchanger from Northern would work except this kind of stove fits into the Fireplace hole with a pipe going up.
Reply:Boilers grow quite a bit, way more than you think. I'd weld the back and let the front float. Jmo
Reply:You want a "magic heat" if you think all your heat is going up the flue.Best $150 you will ever spend if you use a wood stove as your primary heat source.old Miller spectrum 625 Lincoln SP-135 T, CO2+0.025 wireMiller model 250 and WP-18V torchCraftsman 100amp AC/DC and WP-17V torchCentury 115-004 HF arc stabilizerHome made 4 transformer spot welderHome made alternator welder
Reply:As mentioned earlier, "Magic Heat" won't fit do to the way the Stove sits in relation to the Fireplace.I'll try posting a photo later today.....
Reply:Believe it or not, Most boiler tubes are only rolled at the tube sheets and drum joints, seldom welded....They are roll expanded in place and usually never leak a drop when in service for many many years....That applies to both common watertube and firetube boilers.Sometimes you will find a boiler that has both rolled and then 'seal welded' tube ends, but the seal welding usually is applied only on certain firetube boilers at the end of the first pass on the rear tube sheet where combustion gasses are hottest, often as a field repair and not by original design.The neat thing about rolled tube end construction is it is a proven design and MUCH cheaper then welding, because welding on a pressure vessel is extremely costly and time consuming if done to code....Plus, replacing a tube is lots easier and cheaper if roll sealed in place.
Reply:Originally Posted by drujininIt has a damper inside the stove.Its just that it is a brick lined iron box with minimal baffling in it.I've even thought of putting a sheet metal envelope on the back and blowing air through that.The heat exchanger from Northern would work except this kind of stove fits into the Fireplace hole with a pipe going up.