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Horizontal concentric venting under metal, unvented soffit?

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exactly

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If I were to either move or remove this door or vent forward of it (to the left in this photo), is there a reason a typical concentric vent would have to stick out beyond the soffit? If it matters, I am in Minnesota, the siding is vinyl, and the the soffit is metal, unvented (not perforated like some), and sticks out 18".

Second, how would I deal with the fact that the soffit is about 11" lower than the 9' ceiling in the garage? I am not sure how low the vent needs to be below the soffit, but if it were even 1', that means the vent will penetrate the wall about 7' from the floor. Would the heater not have to hang at roughly the same level and thus be too low? Or could I use a short vertical piece to have the vent a bit lower than the heater?

I would rather vent vertically, but it sounds like it would have to stick up at least as far as anything within 10' of the vent, including the roof or the adjacent wall. is this correct? It just sounds more complicated and impossible, if not very unsightly. It's a two-car garage with a 7/12 pitch roof.
 

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Firebrick43

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First, with snow, low height, and decent eaves you are getting into an impossible situation to use a concentric vent. Also concentric venting is not that great.

I assume you can use pvc for venting? Does your garage have an attic? You could do intake from the soffit and run exhaust up the attic and out near the peak? Use a lead boot for a long lasting leak free seal
 
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OP
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exactly

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Firebrick43 said:
First, with snow, low height, and decent eaves you are getting into an impossible situation to use a concentric vent. Also concentric venting is not that great.

I assume you can use pvc for venting? Does your garage have an attic? You could do intake from the soffit and run exhaust up the attic and out near the peak? Use a lead boot for a long lasting leak free seal
Click to expand...


The heater will be a separated combustion unit by Modine or Sterling, so I don’t believe PVC is an option. There are high efficiency units available but at 50,000 BTU I do believe they’re too large. Or maybe they’re not? Anyway, why is a concentric vent bad, again?
 
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stokefire7 said:
I'll need more info to help you.
Click to expand...


What would you like to know? I wrote up a very, very long post expressing a lot of frustration over a lot of things, providing detailed photos, and dimensions, but I took this route instead of posting something I feel most would not read. I will be able to grab that and share it in a few hours, but is there anything I can answer for you right now?

7/12 pitch roof, two car, attached garage, the heater will be a separated combustion unit by Modine or Sterling, there is a vertical wall behind the garage for the second story, but the only window is on the side wall, the soffit is solid, not vented, is metal, and sticks out only 18 inches. The soffit is 18 inches above the door on the outside. The inside ceiling is 9‘1“ and is about 29 inches above the door, so the soffit is about 11 inches below the 9 foot interior ceiling. I don’t mind moving the door.

I am skeptical of a vertical vent because all of the documentation I read makes it sound like anything, including the roof, within 10 feet means that the vent needs to stick up 2 feet past it, and I do not want a 7 foot tall pipe coming out of the roof.

I had a few local HVAC companies come out to quote the job, and only one got back to me. And even so, he told me a couple days later that there was one more thing, which was that it’s going to be a very tall roof vent with wires to keep it stable. Very unsightly.

Is this garage just not meant for this type of heater at all? Is there a reason I can’t just move the door and vent straight out the side?
 
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stokefire7

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I'm guessing something like the "Hot Dawg" ?
Should probably take a closer look at vertical venting, that's pretty standard option for venting.
 
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stokefire7

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I am skeptical of a vertical vent because all of the documentation I read makes it sound like anything, including the roof, within 10 feet means that the vent needs to stick up 2 feet past it, and I do not want a 7 foot tall pipe coming out of the roof.

I'm certain that you're misunderstanding this.
 
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The Cobbler

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I am pretty sure you cannot run horizontal flue pitched down . so to come out of your wall below the soffit may be a bit problematic sounds like .
can you locate the heater somewhere else?
I understand with the required height of Bvent and the adjoing wall is a concern too
 
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stokefire7

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It may be better placement on the other corner as you have the door right there. Do you have the option for either corner(of the garage) ?
 
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stokefire7

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The Cobbler said:
I am pretty sure you cannot run horizontal flue pitched down . so to come out of your wall below the soffit may be a bit problematic sounds like .
can you locate the heater somewhere else?
I understand with the required height of Bvent and the adjoing wall is a concern too
Click to expand...

Time stamp ? The same. LOL
 
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stokefire7

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If it were me, I'd put the unit a third of the way in, instead of the corner (you'll have to run pipe in the attic and you won't have room in the corner), your'e gonna use attic space to offset and meet the horizontal distance requirement.
 
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stokefire7

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That unit will probably need to sit away from the wall 3 1/2 '. Figure unit, 3" x 12" vent section, 3" tee, and clearance. Joist layout has something to say in this (first and foremost).
 
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D45

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Follow the manufacturers installation manual with what vent kit you choose

22_zpsergta7hw.jpg
 
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exactly

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It's been nothing but frustration the past week or so, between the second contractor I had come out for a quote not being able to be reached, and none out of the dozen other contractors I've called being reachable after promising a quote or call within a day or two. The second contractor I had come out when the first was unreachable for the first couple weeks has dragged his feet, with repeated promises of calling back...but nope, he seems to have bought the farm or something. Also, the price for an install has quickly escalated from $2,600 to $4,500. My local permits and inspections office cannot be reached and does not return calls. I will not do gas work myself, so I might just have the gas work done by a friend without permit or inspection, and I will hang and vent a heater according to how I interpret the instructions combined with the help I can get on here. Is this reasonable?
 
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stokefire7

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I've ran off three concrete guys myself, still have the last ones forms and stakes from over a year ago.
 
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stokefire7 said:
I'm guessing something like the "Hot Dawg" ?
Should probably take a closer look at vertical venting, that's pretty standard option for venting.
Click to expand...

You bet. Modine's HDS-45 (separated combustion) or maybe the Sterling GG45 (website has been offline for two weeks and so install manual not available). The point here is separated combustion.

stokefire7 said:
You have a garage attic , right ?
Click to expand...

Yes, and I have an attic ladder that I installed earlier this year. Drywalled garage ceiling, no insulation in attic yet.

stokefire7 said:
I am skeptical of a vertical vent because all of the documentation I read makes it sound like anything, including the roof, within 10 feet means that the vent needs to stick up 2 feet past it, and I do not want a 7 foot tall pipe coming out of the roof.

I'm certain that you're misunderstanding this.
Click to expand...

I think so too, but here's what I find in the Modine HDS installation manual, located here, pages 7 and 8: https://modine.worksmartsuite.com/PORTAL/io_modules/IOGETIMAGE.php?type=stream&filename=6-584.pdf

What's odd is the Sterling unit in separated combustion mode indicates that it must be 2' higher than the roof if within ten feet, but I do not see such language in the Modine HDS manual. In the normal Modine Hot Dawg manual, I do see it, though.

stokefire7 said:
It may be better placement on the other corner as you have the door right there. Do you have the option for either corner(of the garage) ?
Click to expand...

Garage door faces north, and I wanted to place in SW corner. SE corner has obstructions that cannot be resolved, leaving only the NW and NE corners. It's a standard 16' garage door in a 22' long wall, so there's track that hangs down a bit from the 9' ceiling about 2.5' in from the side walls. Would the heater fit in this space? That would be the front of the garage.

---

One specific question I have at the moment is if I do go out the side, with a 9' ceiling and an eave that's 11" below that (I think I mistyped in my previous reply), does the heater have to hang relatively low in the garage so the vent can go more or less straight out (taking into account the required shallow slope)? Or is there another way to get the vent from, oh, 8' height at the heater on the interior to, say, 7' height on the exterior (to be the required 12" below the eave overhang, per the install manual)?
 
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stokefire7

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You may be on to something with where you want it. Should verify distance requirements.
1) 4' from any door
2) 1' below the eave (I couldn't find that)
3) vent terminal will extend 16" from wall (will this terminate over a sidewalk ? and where is this in conjunction with the end of the eave ? )
 
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stokefire7

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Looking at the concentric vents, Modine shows two configurations of vent terminals, one is directional the other is not.
 
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ripperd

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exactly said:
One specific question I have at the moment is if I do go out the side, with a 9' ceiling and an eave that's 11" below that (I think I mistyped in my previous reply), does the heater have to hang relatively low in the garage so the vent can go more or less straight out (taking into account the required shallow slope)? Or is there another way to get the vent from, oh, 8' height at the heater on the interior to, say, 7' height on the exterior (to be the required 12" below the eave overhang, per the install manual)?
Click to expand...

I have the beacon morris 45kbtu unit (rebranded sterling I believe) with the separated combustion kit.

The exhaust is forced, so there is no "draft" component to it. I have the same setup where the eave is lower than the indoor ceiling height. I just had the exhaust drop down a foot or so before exiting. No permits here but I don't recall seeing anything against that in any literature I read.
 
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ripperd said:
I have the beacon morris 45kbtu unit (rebranded sterling I believe) with the separated combustion kit.

The exhaust is forced, so there is no "draft" component to it. I have the same setup where the eave is lower than the indoor ceiling height. I just had the exhaust drop down a foot or so before exiting. No permits here but I don't recall seeing anything against that in any literature I read.
Click to expand...


Wow! This is great. Thanks for sharing! Would you mind sharing a few photos? How far below the eave is the top of your exhaust pipe? How far out the wall does the vent kit extend? Does it extend beyond the eave? This might be my solution, though I would have to move a door first. Also wondering...how long have you had your BM unit?
 
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ripperd

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exactly said:
Wow! This is great. Thanks for sharing! Would you mind sharing a few photos? How far below the eave is the top of your exhaust pipe? How far out the wall does the vent kit extend? Does it extend beyond the eave? This might be my solution, though I would have to move a door first. Also wondering...how long have you had your BM unit?
Click to expand...

This is what it looks like on the inside. If you look close I didn't use stainless for the angle bits - It is taped with the proper single wall tape and easy to inspect for corrosion. You could do stainless here but they only come in 45's or 90's and are not adjustable. so alignment is much trickier. The rest is all the proper cat3 stuff.
IMG-20201030-WA0001_resized.jpg

On the outside, I have it coming out about 12" below the soffit, and I had to get an extra 36" kit to extend the exhaust part far enough so that the entire end cap terminator is 12" beyond the facia on the soffit. I have not seen any evidence of frosting or exhaust ingestion near the soffit/facia. I don't have a pic though, sorry.
 
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yeldogt

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ripperd said:
This is what it looks like on the inside. If you look close I didn't use stainless for the angle bits - It is taped with the proper single wall tape and easy to inspect for corrosion. You could do stainless here but they only come in 45's or 90's and are not adjustable. so alignment is much trickier. The rest is all the proper cat3 stuff.
IMG-20201030-WA0001_resized.jpg

On the outside, I have it coming out about 12" below the soffit, and I had to get an extra 36" kit to extend the exhaust part far enough so that the entire end cap terminator is 12" beyond the facia on the soffit. I have not seen any evidence of frosting or exhaust ingestion near the soffit/facia. I don't have a pic though, sorry.
Click to expand...

Vent must slope -- even "horizontal" system have 1/4 (my memory) .... are you sure you followed the directions?

Does not look correct
 
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yeldogt

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exactly said:
I was originally resistant to this but may end up pursuing it after all if a ceiling-mounted heater does not pan out. Thanks!
Click to expand...

They are nice units .... make sure you get the vented unit. They are sealed combustion. Very easy to install -- they make modulating as well.

I have one from another manufacturer. In a garage it may need to be up 18" -- mine is in my 1600sf studio.

It's just a single small hole in the wall behind the unit -- concentric metal flue Maybe a 3" hole . Mine is propane so the fuel line goes outside as well.
 
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ripperd

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yeldogt said:
Vent must slope -- even "horizontal" system have 1/4 (my memory) .... are you sure you followed the directions?

Does not look correct
Click to expand...

Yes, I made sure the exhaust side does slope down toward the outside. You can see a frozen drip puddle on my lawn as evidence on the cold days!
 
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yeldogt

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ripperd said:
Yes, I made sure the exhaust side does slope down toward the outside. You can see a frozen drip puddle on my lawn as evidence on the cold days!
Click to expand...

The slope is up .... not down. Flue gas must go up even when powered.

I googled the model .... it has a positive 1/4 slope
 
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Mainiac Mat

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Per the Modine installation manual...

attachment.php


I'm <3' off the gable end wall, so I'm going to ditch the drip leg and pitch down a whopping 1/2" total and let the condensation drip out the wall terminal.

Note that dim 'A' comes form table 10.1 and is 11" for 75K BTU and below units.

12.JPG
 

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Mainiac Mat

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If I understand the OP's situation correctly and was in his shoes, I'd vent vertically with a B vent into the attic, use a 45 to turn away from the house and rotate the pipe to angle it towards the ridgeline while traversing the height of the attic, and then another 45 deg and out the roof just to one side of the ridge. Your initial offset from the common wall (I think he sad ~3') plus the additional distance gained in the attic should get you close enough to the 10' mark to call it good enough. Pop out 3' straight up and call it done.
 
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