On Mon, 8 Aug 2011 03:49:41 -0700 (PDT), Mikepier
wrote:

I have a 6 month old Sears (AO Smith) 50 Gal gas water heater. While
in my basement the other day, I noticed the plastic red " HOT" and
blue "COLD" rings around the heat trap nipples were melted around the
area where the exhaust flue pipe is.
So I raised the T-stat to fire up the water heater to test, but found
no excessive heat around the exhaust and draft hood. Testing with a
match confirmed the draft was good. By the way, the exhaust pipe is 3"
rigid duct. The specs to the water heater allows 3" or 4" ducting. I
took apart the duct to check for blockage, and it looked clear.
Now last night I was in my basement again, and this time I noticed
excessive heat around the draft hood, So much that I could not keep my
hand there for that long. When I did the draft test with a match, the
flame was blown out. I turned off the water heater and tested again
with the match, and the flame was still blown out.
I also tested it with my furnace vent without the furnace running, and
that was blown out too.
The only thing I can think of is that it was very humid outside last
night and the air was still, possibly causing no updraft.
I rechecked about an hour later, and the draft was good. What could
cause this?


Somethiung nesting in your chimney???