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Mike Lamb

Furnace Install in Cold Climate Attic

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Does anyone have a handy diagram, product info and/or language re: installing a condensing furnace in a cold (Chicago) climate attic? Thanks.

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Thanks. I was thinking (in general), besides what you mention, it should be in an insulated room to help prevent ice damming, condensate freezing, moisture problems and that sort of stuff. At least, that is what I'd like to recommend.

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Does anyone have a handy diagram, product info and/or language re: installing a condensing furnace in a cold (Chicago) climate attic? Thanks.

Sure, the manufacturer usually provides comprehensive information.

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The newer construction I see has the attic furnace in its own room which I think is a good thing. I was looking for something to substantiate this beside my personal recommendation. I can’t find anything from manufactures yet that does so.

I do come up with, "The condensate drain should be protected from freezing when in unheated spaces."

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I do come up with, "The condensate drain should be protected from freezing when in unheated spaces."

And it shouldn't drain to the exterior. It should drain down through an internal wall.

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I do come up with, "The condensate drain should be protected from freezing when in unheated spaces."

And it shouldn't drain to the exterior. It should drain down through an internal wall.
Yep, had one of those about a year ago in a D.R. Horton home up in Issaquah Highlands. Furnace in the attic with the condensate drain routed across the attic under 15 inches of insulation and then down through the top plate at the eaves where some horse's ass with teeth had placed insulation in the wall below on the inside of the drain instead of on the outside, leaving the pipe out in the uninsulated space.

The client had the inspection in warm weather and moved in during warm weather. About three weeks after he fired up his furnace and about two weeks after a freeze we had here that had burst pipes all over the county, he noticed a dark stain on the ceiling above the stove in the kitchen. He climbed up and poked the stain, his finger went through the drywall and water began dripping out of the ceiling. He called D.R. Horton and they sent someone out. They figured it was a toilet pedestal seal in the bath over the kitchen so they replaced the seal and told him they'd be back in two days to patch and paint the ceiling. The drip didn't stop; he had to put a bucket on top of the kitchen cabinets and capture the water. D.R. Horton came back, figured they'd screwed up the seal replacement and put another in - this time more carefully but the dripping persisted. They tore into the wall of the bath and found the incorrectly insulated pipe and the inside of the wall cavity black with wood rot fungi.

They informed the client and he called me. I hot tailed it out there to see what the issue was. After he'd explained it to me I pointed out that it was a latent issue and that there wouldn't have been any way that myself, or any other inspector, would have found it. I reminded him of what I'd told him when we went over the contract - I don't have X-ray vision now, never had it and don't expect to ever have it. He still wasn't happy - said I should have told him that he was buying a "defective" home. I thought, "There's something defective here alright and it's not the home."

You can't please everyone all the time, you can only please some of the people some of the time.

ONE TEAM - ONE FIGHT!!!

Mike

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The newer construction I see has the attic furnace in its own room which I think is a good thing. I was looking for something to substantiate this beside my personal recommendation. I can’t find anything from manufactures yet that does so.

The manufacturers' instructions usually specify Armaflex on the PVC exhaust and heat tape on the condenstate drain for any sections in unconditioned spaces.

There's no source stating any requirement for an insulated room.

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There's no source stating any requirement for an insulated room.

That's what I discovered several years back when I would rail about furnaces just sitting out in the middle of the attic.

I got my comeuppance by a couple good furnace tech's who called me out with one of my favorite phrases, i.e., "you got any credible reference source for that opinion, sonny?"

I did not, and learned a valuable lesson.

Running water isn't going to freeze very quick (if at all), especially when it's warm condensate. I just make sure the drain pipe has a decent pitch, and that it drains to an interior wall.

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This is what the installation manual for my condensing furnace, built and installed in 2004, says:

“IMPORTANT: The condensate drain should be installed with provisions to prevent winter freeze-up of the condensate drain line. Frozen condensate will block drains, resulting in furnace shutdown. If the drain line cannot be installed in a conditioned space, then heat tape should be applied as required to prevent freezing (per manufacturer’s instructions).â€

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There's no source stating any requirement for an insulated room.

That's what I discovered several years back when I would rail about furnaces just sitting out in the middle of the attic.

Yeah, and why folks out here in crawlspace country roll our eyes and chuckle when we read a post by a back-easter complaining about furnaces and water heaters being in garages. [:-boring][:-smirk]

ONE TEAM - ONE FIGHT!!!

Mike

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I see them, here in Central Kentucky, in attics and crawl spaces all the time. Those are the most common locations around here. In the house or garage is not quite so common.

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Common write-ups for attic units include:

The insulation should be removed from overflow drain pan under the attic heating & cooling unit. It can block the overflow drain line and cause the overflow water to drip onto the ceiling below.

There is no safe walkway or working platform for the attic heating and cooling equipment. Generally accepted building practices call for a 24 inch wide walkway, from the attic hatch to the equipment, and a 30" x 30" working platform on the side of the unit where access panels are located for the safety of repairmen working on the equipment. I recommend the addition of a safe walkway and working platform for this attic heating & cooling unit.

There is no secondary condensate drainage protection for the attic heating & cooling unit. Generally accepted building practices call for secondary condensate drainage protection for units located where damage to the building will occur if the primary condensate drain plugs up with gunk. The secondary condensate drainage protection is usually a drain pan with a separate drain to a visible location or a water detection device that will shut the unit down if the primary drain is blocked. Failure to have a secondary means of condensate drainage protection can allow water to damage the structure below the unit if the primary drain blocks up. Have a heating and air conditioning contractor install a secondary means of condensate drainage protection.

I've yet to see a condensate drain line freeze up.

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There's no source stating any requirement for an insulated room.

That's what I discovered several years back when I would rail about furnaces just sitting out in the middle of the attic.

I got my comeuppance by a couple good furnace tech's who called me out with one of my favorite phrases, i.e., "you got any credible reference source for that opinion, sonny?"

I did not, and learned a valuable lesson.

Running water isn't going to freeze very quick (if at all), especially when it's warm condensate. I just make sure the drain pipe has a decent pitch, and that it drains to an interior wall.

My two favorite references are physics and logic. Unfortunately alot of contractors don't understand either.

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My two favorite references are physics and logic. Unfortunately alot of contractors don't understand either.

I use them disguised as 'common sense'. Not having much success there either.

Marc

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I believe it is best practices not to spend the money on a 90% in the attic be to put in a variable speed 80% and a higher SEER for A/C

[:-monkeyd

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Running water isn't going to freeze very quick (if at all), especially when it's warm condensate. I just make sure the drain pipe has a decent pitch, and that it drains to an interior wall.

Don't forget that there's a trap in there somewhere. Not all the condensate drains away when the furnace shuts down.

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Don't forget that there's a trap in there somewhere. Not all the condensate drains away when the furnace shuts down.

About 2/3's of the installs I see lack traps.

On the AC side, if there's a trap, there's rarely water in there since the AC isn't running for a month before the heat kicks on. If there is, I've never seen it be a problem. I suppose I could care more about this, but honestly, I don't.

On the combustion condensate side, it's not trapped, it's warm, and it's running water.

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If it's a condensing furnace (the original topic) then there is almost certainly a trap either installed or built in. A trap is needed to form a plug so that the forced exhaust doesn't spill through the condensate drain and into the house.

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OK. I still don't care. Maybe I should.

Anyone got a graphic to put up? I'm busy writing reports and don't have the time to look.

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For those with garage furnaces, we just installed a new one on Wednesday and this one needs drainage. We have no drain in garage and there is separation of house and garage by brck wall where breezeway used to be. Any ideas? LAst furnace was from 1957 and didn't shed water. do we need to use a different furnace? We cant tube the water outside due to freezing Chicago weather. L

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