Furnace "chimney"

[not sure]

My uncle gave my his old house furnace when he upgraded to a high efficency. I'm going to install it in my garage. It uses a 4" draft exhaust. I was going to go out the wall and up to avoid cutting a hole in my newer shingled roof. Now I'm considering going through the roof for simplicity. I also never liked roof chimney because that's just another possible leak down the road. The furnace is located near the center of the garage so i was wondering if it was possible to run the pipe directly out of the ridge?

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[sixty4]

My uncle gave my his old house furnace when he upgraded to a high efficency. I'm going to install it in my garage. It uses a 4" draft exhaust. I was going to go out the wall and up to avoid cutting a hole in my newer shingled roof. Now I'm considering going through the roof for simplicity. I also never liked roof chimney because that's just another possible leak down the road. The furnace is located near the center of the garage so i was wondering if it was possible to run the pipe directly out of the ridge?

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I would ask the manufacture of the furnace. Is it gas/oil what venting do they want? B vent gas L vent oil, ventilated thimble Are you passing through an unconditioned space? I have never seen one through a ridge vent at the top of a roof.

 

[not sure]

Natural gas. Its an old heil unit. It had 4" galvanized single wall on it before. The ceiling is finished with steel. So above that is @4" of unconditioned attic. Would a wall thimble be easier?

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[blkhonda1991]

sounds like it would be a messy detail trying to flash at the ridge...

 

[sixty4]

Natural gas. Its an old heil unit. It had 4" galvanized single wall on it before. The ceiling is finished with steel. So above that is @4" of unconditioned attic. Would a wall thimble be easier?

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Heck yes! Listed and labeled for wall pass through. Just mind your soffit vent distance when you go through.

 

[not sure]

Where do i get information on soffit distance and such?

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[not sure]

Then i have to figure out how to run the thimble through my wall pro-rib steel and seal it from external leaks

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[SGKent]

I was just researching furnaces and reading up on this the other day on the Carrier site. Bryant, Payne, Carrier - they are all similar. On venting, many older ones are designed for a straight draft. If you put bends to go out the wall you will need to add some kind of a vent fan.

 

[not sure]

I would like to find a used high efficency so i don't need a chimney. Just a pvc pipe. Maybe I'll keep looking

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[not sure]

I'm kinda back to square 1. I either Need to run a chimney up out of the roof or find i high efficency somewhere

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[anythingyoucanimagine]

I'm not an hvac person or a roofer. All I know is enough to get me in trouble with regards to my specific oil fired boiler and asphalt roof shingles.

Roofing and flashing isn't really all that hard. If done properly it shouldn't give you any issues. Don't be scared of it, they make easy "cheater" sleeves and gaskets that slide right up under the shingles. Stuff like angle grinders and oscillating tools make easy work of clipping edges or making slots.

I did something like this last summer and it was easy:
https://www.homedepot.com/p/Oatey-1...Steel-Drip-Edge-Pipe-Flashing-11815/100212851

Up through the ridge vent might work... I don't know that I've ever seen anything like that but I'm not a roofer or a contractor. I think it would be easier to go out through a roof pitch vs. at the ridge but as long as you pay attention to where the water wants to go I guess it would be fine.

I put "run chimney pipe through roof peak" into Google and searched images. I didn't really see anything so my gut says maybe it's a bad idea (I prob wouldn't do it). I did find this:

http://icc-chimney.com/en/excel

Scroll down, they make a flashing product specifically for roof ridge/peaks.

 

[not sure]

I think i have a solution. Checked on Craigslist and found another furnace. High efficency so only need to run 2" pvc out the wall and the cool part is it's the identical furnace to the one in my house! So i already know how it works and how to fix it.

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