Question about high efficiency Furnace Exhaust

Posted by Pep on January 16, 2007, 10:48 pm

I have had two contractors in to price out a new high efficiency (90%)
gas furnace for my 25 year old home located in Calgary Alberta. So we
get some pretty cold days

Both have said that a new horizontal exhaust is required out the side
of the house. Both contractors will also drain condensed water from
the furnace to a floor drain inside my basement.

One didn't recommend the high efficiency furnace. He said that the new
exhaust will produce a sizable condensation cloud which will frost over
a window which is about 3-4 feet above the exhaust. As well he thought
condensation would freeze on my neighbors house which is about 6-8 feet
away.

Does a high efficiency gas furnace really produce a cloud of
condensation? (It gets quite cold here, with a lot of freeze thaw
cycles over the winter)

Would the furnace exhaust come out with enough force to frost up my
neighbor's exterior wall 6 feet away?

thanks

Posted by WDS on January 16, 2007, 11:09 pm

Pep wrote:

> I have had two contractors in to price out a new high efficiency (90%)
> gas furnace ...
> One didn't recommend the high efficiency furnace. He said that the new
> exhaust will produce a sizable condensation cloud which will frost over
> a window which is about 3-4 feet above the exhaust. As well he thought
> condensation would freeze on my neighbors house which is about 6-8 feet
> away.
> Does a high efficiency gas furnace really produce a cloud of
> condensation? (It gets quite cold here, with a lot of freeze thaw
> cycles over the winter)

Yes it does. However...

> Would the furnace exhaust come out with enough force to frost up my
> neighbor's exterior wall 6 feet away?

We have a 90+% efficient furnace and while there is a bit of a cloud it
would not frost up a window 6 feet away. I suppoe the ones they
recommend could be different, though.

Posted by Steve Barker on January 16, 2007, 11:15 pm

I wonder if he's ever heard of an ELBOW.? Aim it down or sideways and it
should avoid both problems. DUH

--
Steve Barker

>> Does a high efficiency gas furnace really produce a cloud of

> condensation? (It gets quite cold here, with a lot of freeze thaw
> cycles over the winter)
> Would the furnace exhaust come out with enough force to frost up my
> neighbor's exterior wall 6 feet away?
> thanks
>

Posted by Bubba on January 17, 2007, 5:28 pm

On Tue, 16 Jan 2007 22:15:18 -0600, "Steve Barker"

>I wonder if he's ever heard of an ELBOW.? Aim it down or sideways and it
>should avoid both problems. DUH

Down or sideways? Duhhhh yourself. Obviously you've never looked at
the installation manual on venting a 90% eff furnace.
You would have many many callbacks with that "fix".
Bubba

Posted by Goedjn on January 17, 2007, 6:33 pm

wrote:

>On Tue, 16 Jan 2007 22:15:18 -0600, "Steve Barker"

>>I wonder if he's ever heard of an ELBOW.? Aim it down or sideways and it
>>should avoid both problems. DUH

>Down or sideways? Duhhhh yourself. Obviously you've never looked at
>the installation manual on venting a 90% eff furnace.
>You would have many many callbacks with that "fix".

My inclination, (without benefit of instructions)
would be to 'T' it into a larger pipe, pointed up and down,
and open at both ends. But not until a problem
became apparent.

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