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venting-upgrade gas heater to high efficiency

I've been considering replacing my older gas heater with a high efficiency unit and since my furnace has stopped igniting, no time like the present.  I also purchased a tankless gas water heater that I've been waiting to install.

The old furnace and water heater are in a closet by themselves and share a roughly 40 year old block chimney (house is about that old)  My question is can I vent these both into that Chimney or not?


  • HenryHenry Member Posts: 963

    The instalation must be done by a licensed installler, according to the manufacturer's instructions and NFPA54 in the US and B149.1 in Canada. Certain areas have additional regulations above and beyond the National Gas Code. High efficiency equipment cannot be vented in a regular chimney.

    BTW, tankless water heaters do not save energy nor do they perform as well as other gas heaters in cold climate areas. We refuse to install ANY!
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