Expert: James Ball - 11/12/2009

Question
We are told we have a Thermocrete liner; it has some hairline cracks.  (We were told the liner was installed with an inflated form and springs, not sprayed on as the website I found depicts.)  The liner is inside a concrete block chimney.  The prior owner said it was installed because they had a chimney fire.  It's 7" in diameter.  The pipe from the wood furnace is 8".  One chimney repair person says the thermocrete liner must be pneumatically chiselled out enough to put a 7” metal liner put in (at $2800!!!).  Another repairman says it's fine to use as is as long as we burn hot (top of the “burn” zone for at least 15 minutes) every day to keep creosote from accumulating.  Your advice?  Is there a warrantee that might help us?  (I can ask the prior owners when it was installed).  If not, can a thin coat be sprayed over the cracks?

Also, we have a propane furnace with a separate flue adjacent to the wood furnace.  Can we solve this by simply venting the wood furnace out the same flue?  (We must physically turn on whichever furnace we want to use; it’s not automatic.)

Thank you!


Answer
Hello Deb, you can not put it in the furnace flue ever. as far as the chimney goes it should never have been down sized (you can not reduce the flue size on solid fuel units) did you contact Thermocrete? http://www.thermocreteusa.com/
do you have room to install a new Stainless Steel double wall Class "A" chimney?, if not then the old chimney must be repaired for proper venting which means a 7" liner
James