AskCodeMan

I want to replace my current natural gas fireplace with a pellet stove (insert). The gas fireplace as a 8 inch vent pipe though the roof (about 20 ft.). The pellet stove has a 4 inch pipe so my question is can I insert the 4 inch pipe into the 8 inch pipe 4 or 5 ft. seal it so no gases come back down, or will I have to replace the 8 inch pipe with all new 4 inch pipe. Thanks, David

I will contact my expert on those things and have him answer your question.

David, you need a qualified professional to inspect your present installation, cross-check it against the pellet stove and pellet vent pipe mfrs. listed instructions to see what can be done, then run it by your local bldg. dept to see if they require a permit or inspection. You also need to check with your homeowner's insurance.

There are some brands of factory chimney that make adapters for gas vents but since pellet vent is listed to UL 641, which is also for oil, you may not find what you're looking for. I'm trying to envision an 8" gas vent--that's really huge for gas. The inspection will determine the brand, clearances to combustibles, firestopping, support, etc. Ask for an NFPA level II inspection. You will want someone who is a F.I.R.E Certified Inspector preferrably but also one that holds an Pellet certfication by the National Fireplace Institute.

What area do you live in?

I am in northern Ca, about 50 miles north of Sacramento