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reclaiming heat from gas furnace flue

I have a natural gas forced hot air furnace and would like to reclaim some of the wasted heat that escapes through the flue. The flue is 5" insulated. Any ideas would be greatly appreciated. Thanks

Re: reclaiming heat from gas furnace flue

While theoretically something could be done, practically I don't believe their is anything you can do other than getting a new high efficiency unit.
Playing with the flue would certainly void your insurance for any fires & liability as well as open yourself to carbon monoxide poisoning.
Having a tech ensure the furnace is operating to efficiency is probably the only thing you can do.
I could be wrong, it's happened before.;)

Re: reclaiming heat from gas furnace flue

I don't think it would be a very good idea to try to capture heat from the flue. The flue gases need to be at a certain temperature to properly vent. If they are cooled to much before exiting the flue water can condense out and onto the walls of the flue and then drip back down to the furnace. Plus I would have the same concerns as Ed that you don't want to go altering the flue that could possibly introduce CO into the home and that is definitely not a good thing.

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