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what do I use to seal the HW heater flue where it enters a stone chimmney?

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asked in House Chimney by phil (120 points)
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1 Answer

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Hi Phil, 
Depending on the size of the gap between the water heater vent connector and stone chimney wall opening you can use two products (separately or together).
If the metal connector fits tightly into the chimney you can seal remaining gap with high temperature fire rated caulking – an example: http://www.grainger.com/Grainger/3M-Fire-Barrier-Sealant-5PB37?cm_mmc=CSE:GoogleBase-_-Safety-_-Fire%20Protection-_-5PB37&ci_src=14110944&ci_sku=5PB37
If it is a larger gap, use furnace cement to fill that space, let it set for whatever time is suggested by its manufacturer (example - http://www.rutland.com/productinfo/chimney-sweep-furnace-cement.html) and if necessary; finish the job with a bead of high temperature fire rated caulking.
Whatever product you pick, you should check with your local building department if it is approved for this particular purpose in your jurisdiction.
answered by darekrudy (21,730 points)