DIYbanter - View Single Post - Gas Hot Water Heater and Attic Fan conflict

CJT

wrote:
All,

This is a good one. About 8 months ago I replaced my gas hot water
heater with the same model and it has been working normally since. I
have replaced probably 10-15 heaters in my life and never had a
problem. Earlier today I noticed that some of the plastic fittings
around the hot and cold water inlets on top of the tank were slightly
melted directly adjacent to the flue. This melting was new, since
there was a clear outline of clean metal where the fitting used to
be. I was racking my brain trying to figure this out - and came up
with what I believe to be the cause. Read on.

A week ago I installed a big attic fan to draw the hot air out and
cool the house and I have observed the fan interfering with the
updraft of the water heater by performing the following test. With the
fan off and water heater running, I tested the draft at the water
heater flue with a smoking match and found it to work fine (drew the
smoke right up). Next, I performed the same test after the attic fan
was running for 2 minutes and it didn't draw the smoke up.

This seems to pose a health and safety hazzard for two reasons -
carbon monoxide and heat. Has anyone else experienced this? I have a
CO detector in the boiler room and it has not gone off, however one
never knows.

Any thoughts, comments, suggestions, or discussion would be great.

Thanks.

My attic fan came with a warning regarding a similar situation with
attic fans and attic-mounted furnaces. There may even be something
in the code that requires interlocks between the devices.

Did you carefully read the instructions and do your research before
mounting the fan?

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