Question about high efficiency Furnace Exhaust

[Pep]

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

[WDS]

Yes it does. However...

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.

[Edwin Pawlowski]

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 house.

[Steve Barker]

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

[houli1955]

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.

[Tom The Great]

imho:

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 kicking yourself.

Just thinking out loud....

tom @

[m Ransley]

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.

[m Ransley]

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.

[Paul M. Eldridge]

I had a high efficiency gas furnace in my Toronto home and the vent was directly below my dining room window. I had no issues with window icing but ice did build-up on the PVC pipe itself during sharply cold weather. It wasn't a serious or frequent problem and it was easy to knock off with your boot.

Cheers, Paul

[yourname]

The condensed water is acidic, so if nothing else drains in there and it is cast iron or copper, could very slowly eat it up. My condinsigs at work drain outside, and I get a huge icicle in the winter. They changes it to drain into my slop sink and I keep a bag of marble chips under it in the hope of neutralizing it somewhat. It does eat the rocks away...

Under no conditions let this idiot inside your house again

No, and no.

Actually the condensing furnace exhaust has less moisture in it than the standard[remember the drain?]

[Tony Hwang]

Hi, 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.

[TH]

Be careful of CO if you open the window during the heating season.

[EXT]

I have had a high efficiency furnace for over 20 years, one of the first ones. It exhausts out the side of my basement wall with a "tee" on the end of the pipe to split the exhaust up and down. While there is a cloud of condensation when it is running, it creates no problems, sometimes a small mound of ice on the ground below. It is in a corner of an "L" and does not cause icing on the walls around it. Check other installers, that one doesn't want to install the high-efficiency furnace, probably because he has not learned how to do it properly, which is bad because they have been around for 25 years.

[Chris Friesen]

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.

Chris

[Goedjn]

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.

--Goedjn

[Bubba]

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

[Goedjn]

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.

[Steve Scott]

[Pep]

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?

[Paul M. Eldridge]

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 l>Thanks for the input everyone. Like some have suggested that particular