Can I run gas pipe thru heating ducts?

I was told that pre-heating natural or LP gas will increase the BTUs and decrease the gas usage. I got to thinking that if I run the gas pipes thru the heating ducts the gas will be heated as it is used. I know I can run the pipes, but is it legal to code? According to the length and path of my gas pipes and ducts, I could run at least 80% of all gas pipes inside heating ducts.
Joe Homeowner
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On Apr 29, 5:36 pm, snipped-for-privacy@home.com wrote:

Did the same guy tell you you can get 100 mpg on your v8 by buying a hydrogen generator and running it on water or attaching magnets to the gas line.
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Sure sounds like a troll. But clearly even aside from code issues and simple practicality, is the fact that the premise is wrong.
Sure, if the gas or the combustion air going into a furnace is warmer, the furnace will put out a very small amount of additional heat. However, where is this tiny amount of extra heat coming from? In the proposed scheme, it comes from the heating ducts, where the gas passing through will be cooling the heated air by a tiny amount. It's like trying to drive a generator with a motor wired to the generator.
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On Apr 29, 6:36 pm, snipped-for-privacy@home.com wrote:

Absolutely. If you can get the heating ducts up around 2000 degrees C you can get rid of the furnace! Go for it.
R
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snipped-for-privacy@home.com wrote in news:f3lhv4ltv6qv8lg587fbd5miq2b9ovtv55@ 4ax.com:

Run it through the oven chamber too. Think of the payback when you cook a roast, lasagna, turkey, etc.
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snipped-for-privacy@home.com wrote:

You can also make electricity flow more efficiently by cooling the wires, so run them through the pool to cool them off.
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On Apr 29, 5:36 pm, snipped-for-privacy@home.com wrote:

Sure, I'd just like to be there when you try to explain that one to the next buyers home inspector.
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"Oh but someone on the Internet said it's OK. It must be true."
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