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
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?
It is not that bad. I know of two units, one across the street from me, the
other is a tenant in our warehouse building. I've never seen condensation
on the walls and never saw it go so far that it would be on a neighbor's
My 93.5% Lennox does not produce enough condensation to cloud anything.
Call any manufacturer for recommendations. Do you want to save 12-15%
for ever, put in a 94.5% unit. You should not consider anything else
but Condensing. I believe in England condensing is Law for replacement.
England exports NG and is warmer than the US - Canada, maybe we- U.S.
need to learn from the europeans.
My neighbors house is 4 ft away from my condensing exhaust , no it does
not affect it at -15f nor would it affect it at 2ft away if they had any
wall insulation or not. You gotta idiot hacko telling you this, must be
from the althvac group.
Do you know how cold it can get in Calgary?
How about -35C with wind chill of -50C-ish?
Not all the time but there are days like this.
Here in old neighborhood house to house distance is ~10 feet,
in higher density new neighborhood it's ~8 feet.
I live in Saskatoon, so I feel I can comment based on similar weather.
At -35 (windchill of about -45) my condensing furnace did not cause
frost on my car ~6ft away or on the window directly above the exhaust.
Also, my neighbor's condensing furnace didn't cause frost on my wall
which is about 6ft from his house.
You're more likely to get frost deposits when the air temp.
is rising to right around freezing, and the surfaces are
still colder. at -35F, water vapor will freeze too fast
to deposit on surfaces.
I still think I'd put the furnace in anyway, and
worry about sticking a baffle or something
on the output only if it proves to be a problem.
Thanks for the input everyone. Like some have suggested that particular
contractor was pretty negative on the high efficiency furnace. Due to
my finished basement any new ducting would be a pain to install
compared to a simple mid efficiency furnace.
I did get a total or four bids. Two would only install mid efficiency.
(the laziest and least knowledgeable IMHO). The other contractor who
would install high efficiency was particularly thorough and followed up
well on my questions. And like many have suggest exhaust condensation
will likely not be an issue after asking more questions.
So a new Trane XV90 is being installed next week. Anyone know where I
can get a Trane installation manual?
Congratulations on the purchase of your new Trane furnace. I think
you were wise to go with a high efficiency model; natural gas prices
will continue to trend higher in years to come and so you'll want to
squeeze every last BTU from each cubic foot you burn.
There is a link to the owner's manual on this page:
I have a high efficiency Amana vented horizontally just above the sill
plate. It's 12 degree's f here in Michigan now. There is less condensation
coming out than when you start a cold car to give a comparison. i have a
bedroom window about 4 feet away that has never had condensation on it. The
bushes 1 foot away look no different than those 15 feet away. This will be
our 3rd winter on this furnace. I'm happy with it.
I have a 90%+ unit, and never saw any of this 'frost'. Now I don't
have a window over my flue either, but I do have a wall about a foot
away from the exhaust. No frost.
Might want to get that third estimate. Also, check with your
accoutant, if you don't get your high effeciancy rating, you might not
get the tax credit, and the cost of fuel over the years could have you
Just thinking out loud....
tom @ www.MedJobSite.com
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