Outdoor Wood Boilers / Furnaces

[Fawlty]

Just looking for a little input.. I tried searching, but with no luck. Anyone had any experience with fires involving the sheds protecting wood fired outdoor boilers? I have to perform a cause and origin on a shed constructed of wood that protected the aforemantioned boiler (wouldn't practical sense dictate the roofs should at least be metal? Preliminary photos seem to show a top down burn from around the chimney.. so immediate thoughts are insufficient clearance or non arrested sparks from when the unit kicks in..

anyway, would appreciate any input from anyone who has worked with these units.. shed construction requirements and clearances, baffles etc.

Thanks

[aland438]

I have been to 3 major fires in the last couple of years started by unarrested sparks coming from these units. However, I have not seen one with a shed built around it. I thought the majority of wood burning boiler units were self sufficent. Someone needs to come up with some sort of spark containment for the chimenys on these units. All 3 fires have spread to major wild fires and 2 of the 3 fires have taken down structures. Who knows how many small fires go unreported from these things.

[DepChief135]

What does the manufacturers specifications or installation guidelines require?

[hwoods]

Enclosures?? My son, who lives near Nashville, Tenn. has one, and it is not enclosed at all. The boiler has the normal jacketing on it, there is a rain shield over the gauges, and that's about it. The thing sits on a slab about 50 feet from the house, and the prevailing winds carry the smoke out over the front lawn and away from the house. He's had it going on 10 years, and no problems so far.

[Fawlty]

OK... well post site poke around and info review... It appears that the problem was 'not following manufacturer's construction requirements' . Owner had placed a triple walled vent pipe over chimney, but had left an open 1" gap between roofing OSB and the pipe - manufacturers requirements stated the chimney had to be flashed. The fire occured approximately 2 - 3 hours after the air blower had been operated.. other notes of interest is that that day, the facing wall had been removed to allow access to part of the furnace.

My belief is that after the blower kicked in, sparks or embers were ejected from the chimney and dropped down into the void between the top of the insulation and the roof (wood trusses and OSB) on the opposite side of the view shown. With the wall removed there was plenty of air movement to assist in combustion. Additionally building codes require chimney tops on these units to be at least 3' from the roof line to allow for spark / ash dispersal (this chimney is approximately 18" from roofline).

Would welcome as always any additional thoughts and input. BTW, these units are water jacketted everywhere except the furnace door.. the reason for the shed is to provide insulation for the exterior of the water jacket.

Thanks for all previous posts.

Cheers.