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qwasert : Absolutely you can replace a section of the PVC pipe with 4" cast iron pipe. Using a couple of rubber band clamps on each end to connect the plastic pipe to the cast iron.
This would best be accomplished by a professional plumber, right?
qwasert : Cast iron is a tricky material to work with, it is quite heavy and will require additional supports. If you have the means to hire a professional I would recommend doing so.
Also are the joints between the PVC and the cast iron reliable and durable so I would not have to worry about leaks
qwasert : Yes, the joints are very durrable. I have plumbed many buildings using all cast iron and rubber band clamps call no hub cuplings. i have also done a dombination of both cast iron and pvc pipe. The heat deflecting shield is a good idea as well. If you can achieve a 1/2" space between the deflector and the cast iron pipe there would be no need for a cooling fan.
qwasert : How are we doing so far?
Do you have that specific situation of a need for heat resistance pipe in one area then back to PVC in your experience? I was thinking of a length of about 7' centered above the stove. The rest of the PVC pipe will be hidden behind enclosures I am building now to finish part of the basement.
qwasert : I have used cast iron for penetrating fire walls in the past because of its heat resistance and that it won't melt under extreme temperatures.
Thanks for your time, I will check with a local plumber soon to solicit a bid for the work.
qwasert : As far as a heat baffle goes, I would use 20 gauge galvanized sheet metal, it's quite a bit less expensive than stainless.
qwasert : You are welcome, let me know if you have any more questions.
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