On Tue, 14 Nov 2006 21:33:00 -0600, "Ray O"
<rokigawaATtristarassociatesDOTcom> wrote:[color=blue]
><prodevelopments@yahoo.ca> wrote in message
>news:1163559407.803102.183030@m7g2000cwm.googlegroups.com...[/color]
[color=blue][color=green]
>> HI TP
>>
>> re: PVC furnace exhaust freezes
>>
>> I cannot reply to an older message for you in another forum, so I have
>> found you in this forum and wish to ask you a question.
>>
>> I came across a newsgroup issue where you had freezing from your
>> furnace exhaust. I have the exact same problem and am wondering
>> if/what u did to fix the issue.
>>
>> I have wrapped the exhaust end in heat-tape, but it does not work
>> sufficiently. I am also looking into applying teflon tape to stop the
>> sticking of water....[/color]
>
>Make sure the condensate drain from the inside of your furnace is not
>clogged or leaking.[/color]
If this is a roughly 98% Efficient Condensing Natural Gas (or
Propane) Furnace, there's supposed to be a drain line on the exhaust
stack for the water vapor that condenses out to water before it goes
up the stack. If the furnace is in an unheated area that's subject to
freezing, you might have to provide some more heat to the area to keep
that line from freezing.
If there's a P-trap in the condensate line, you might have to add
both a pipe heating tape and fiberglass insulation wrap around the
pipes. If the furnace maker will allow, you might use soldered Copper
pipe and elbow fittings for that trap, because it will take a lot more
heat input from a hating tape than a PVC pipe ever will. (Without
melting...)
Read The (Friendly) Manual - get a copy of the installation manuals
for your furnace and read it carefully, compare what you have with
what you are /supposed/ to have. Usually those "expert installers"
can't be bothered to leave the books shipped with the unit next to the
furnace for the customer...
I'll bet the installer skipped something vital in the original
installation - either being too cheap to buy the pieces called for, or
too lazy, or just can't be bothered to read and follow directions
because he knows better than the people who designed it. And that's
why you are having the freeze-ups.
(I did Heating and Air for a few years but never installed one of
these - I think the prices are way too steep for the small extra
efficiency you get, especially in a fairly mild non-snow climate with
piped Natural Gas available - far too long of a payback time. Now if
you are in Minnesota or somewhere it gets seriously cold, and paying a
lot more per BTU for Propane, then it makes more sense.)
Note that the condensate from the stack has a very strong Ph one way
or the other - IIRC it's base/alkaline. Either way, the piping and
all other materials used in contact with that water have to be able to
take it. If you are using a condensate pump system (the same one that
handles the atmospheric condensate from the cooling evaporator core in
the summer) to get that combustion condensate to a sanitary sewer
drain, it has to be rated for that particular use.
--<< Bruce >>--
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