I usually run my hand an inch or so away from the flue or
duct. I can feel the escaping air.

--
Christopher A. Young
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..


"mm" wrote in message
...
How do I accurately figure out where air is blowing out
from, from my
furnace flue area, which is next to my hot air duct.

I'v used a match, but it keeps blowing out. Tonight I took
a pencil
and thumbtacked a thin strip of cellophane-like stuff to the
end of
it. Later I added a narrow strip of thin cloth. They blow
like
crazy when the pencil is on the right side of the flue, but
I can't
seem to narrow down where the origin is.

The furnace is a rectangular box, with the heated air duct
attached to
the top and going up from there. The fire exhaust comes
out the
front side just below the top, into the flue collector, a
metal box
which was rebuilt last week and is 14" wide, almost as wide
as the
furnace, and 5" high and 8 inches deep. On the top side of
it
connects the 6" round flue.

When the pencil and its flags are on the left side of the
flue, no
breeze is detected. But in front of the metal box in the
middle,
and anywhere above the box to the right of the flue, the
"flags" on
the pencil blow around like crazy. I'd like to narrow down
where the
air is coming from.


Background:
You've all convinced me that I need to buy a new furnace,
and I will
this year, but I don't want to rush, so I'm still using my
old oil
furnace until I have time to get recommendations, prices,
etc.

As I described in a previous post more than a week ago, I
had the flue
collector repaired by a welder. As Eric predicted, when he
welded one
place, he made a new hole next to the weld.

So I filled all the holes with GE Red Hi-Temp Silicone,
which it says
is good to 650 F intermittent (and a tube from 10 years ago
said it
was good to 600 F.) And it doesn't seem to get anywhere
near that
hot. And the "glue" is certainly in good condition only a
week
later, though perhaps it's not sticking everywhere I think
it is.
Maybe air is escaping. I'll put on more layers, but I'd
like to know
first where the leaks really are. It's not that cold and I
won't be
running the furnace until the leaks are stopped.

When the burner starts, no air comes out through the
repaired