Secondary tube damage from compressed sawdust blocks

[TheLastDeadMouse]

The firewood I've been burning this winter is a big on the wet side (~20% moisture) so I've also been burning some Eco / Enviro / Envi blocks to help bring down the average moisture and also to burn away coals. I've been using the larger ~7lbs. blocks that come in packs of three and stacked them two high in my stove on top of some coals, and the tops were within and inch or two of the secondary air tubes. When they burn they expand and get taller, and actually bent the secondary air tubes up by roughly 1 - 1.5" and cracked the baffle above them.

The question is now is it a problem to use the stove (a Vermont Castings Merrimack) like this? For a pair of tubes and the baffle I'm looking at ~$200 in parts to repair it.

 

[Nick Mystic]

I don't know what stove you are using, so I can't comment on whether it would be safe or not to continue burning before you fix the damage. That said, I know I wouldn't burn my stove with such damage. I have a Jotul F600 and there is an insulating blanket sitting on top of my baffle. With a cracked baffle I would be afraid too much heat would make it through the baffle and blanket and that could result in a warped stove top, which I know would be very difficult to fix and very expensive. I'd bite the $200 bullet and chalk it up to an expensive lesson. Good Luck.

 

[TheLastDeadMouse]

The stove is a Vermont Castings Merrimack

 

[begreen]

Inspect the secondary tube manifolds carefully for cracking. If none, I would pull the bent tubes and try to carefully straighten them out. You might be able to buy a length of the same diameter stainless tubing, cut it to lengths and drill them out to match the bent tubes. The cracked baffle board will need inspection. If it is a single crack it may be able to limp through the season by carefully pushing it together. If it broke into multiple pieces, replace it. The board may be cheaper on eBay. Look for ceramic insulation board, 1/2" thick.

For sure in the future, don't overload a stove with solid fuel. Every manufacture warns that the product will expand. Some do this more than others.