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Old 01-28-2011, 10:11 PM   #1
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Shop heater, gas pipe in contact with vent


Hey guys,

Just finished installing my shop heater. In its previous location it had a 3" vent pipe but in the new location the roughed in vent pipe is 4" so I had to use an increaser.

Because of this, the vent pipe is in contact with the T on the gas pipe, and the vent pipe gets very hot.



Is this something I need to worry about or is it OK this way?

If need be I'll have to put an elbow where the valve is and branch it away from the pipe.

While we're on the subject, is it normal for the vent pipe to get extremely hot? It's been that way for 10 years but it seems like there is more heat escaping through the vent than is coming out front.

Thanks for your help.

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Old 02-05-2011, 01:08 PM   #2
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Shop heater, gas pipe in contact with vent


Hey..

No one seems to be giving you an answer so I figured that I'd give it a shot..

Your OK with the piping as it is.. Actually, I don't see the need for the tee anyway.. You could take it out..

:-) Ken
The K.C. Ament CO., Inc.

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Old 02-05-2011, 01:18 PM   #3
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Shop heater, gas pipe in contact with vent


The two problems that leap out at me are:

1) There should be a drip leg at the bottom of the tee (remove plug and replace with 3" nipple and cap)

2) The b-vent (or what appears to be b-vent) going through the drywall does not have enough clearance from combustibles. It needs the drywall cut back at least 1" around where it's penetrated by the vent, and 6" if it's only single wall venting.
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Old 02-05-2011, 01:42 PM   #4
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Shop heater, gas pipe in contact with vent


Yep, should have a drip leg to catch any debris. You need clearances around the venting at the ceiling and can install the reducer closer to the elbow and extend the 3" pipe to it to clear the gas pipe. Where I am and probably most of Canada you have to have a "base tee" with cleanout/inspection plug/cap on the bottom of the chimney or vertical venting. I would put one there as it catches dirt that falls down the chimney and any moisture and keeps it out of the furnace. Allows for inspection of the chimney later.
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Last edited by yuri; 02-05-2011 at 01:46 PM.
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Old 02-05-2011, 02:16 PM   #5
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Shop heater, gas pipe in contact with vent


Well because I hadn't received any replies I went ahead a few days ago and re-piped it so it was no longer in contact, and at that point I did put a drip leg on the gas pipe.

The vent going through the ceiling is a double wall. It's single wall until it meets that pipe. Actually the HVAC contractors roughed in that one pipe going through the ceiling but the drywallers came afterward and just cut around it.

In my last shop where I installed this heater I remember being supplied with a flange for clearance where the drywall meets the pipe, but it's a little late for that now.

The ceiling is insulated with blown fiberglass so if I cut a clearance around the pipe the insulation is going to fall through the hole. Does the insulation need to be kept back from that pipe as well?

The insulation guys just came 2 days ago and one would assume they followed code when they encountered the pipe, but who knows...

How is this normally handled, with both the drywall and insulation?

Thanks
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Old 02-05-2011, 02:24 PM   #6
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Shop heater, gas pipe in contact with vent


The insulation must not touch and requires at minimum a 1" clearance between the outside of the "B" vent and any combustable, and yes insulation is considered combustable.

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Old 02-05-2011, 02:52 PM   #7
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Shop heater, gas pipe in contact with vent


Just an FYI..

A drip leg is only required where there is manufactured gas.. I'm in Colorado & we don't need them here. But maybe where this gentleman is. Moisture in the line is detrimental to the appliance.

Also Fiberglass isn't a combustible unless it's faced.. The paper is combustible. Fiberglass is used all the time to fireblock pennitrations.

Just my 2cents

:-) Ken
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Old 02-05-2011, 03:00 PM   #8
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Shop heater, gas pipe in contact with vent


Quote:
Originally Posted by KCA View Post
Just an FYI..

A drip leg is only required where there is manufactured gas.. I'm in Colorado & we don't need them here. But maybe where this gentleman is. Moisture in the line is detrimental to the appliance.

Also Fiberglass isn't a combustible unless it's faced.. The paper is combustible. Fiberglass is used all the time to fireblock pennitrations.

Just my 2cents

:-) Ken
I think you have fiberglass confused with Roxul, fiberglass is used as draft stop not fire stop.

And I believe a drip leg is required, I will look that one up.

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Old 02-05-2011, 04:24 PM   #9
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Shop heater, gas pipe in contact with vent


Quote:
Originally Posted by KCA View Post
Just an FYI..

A drip leg is only required where there is manufactured gas.. I'm in Colorado & we don't need them here. But maybe where this gentleman is. Moisture in the line is detrimental to the appliance.

Also Fiberglass isn't a combustible unless it's faced.. The paper is combustible. Fiberglass is used all the time to fireblock pennitrations.

Just my 2cents

:-) Ken
I guess I should have used the correct term: dirt pocket (in this industry, drip leg is commonly used to refer to either a drip pocket or dirt pocket, I sometimes use terms without considering that people not in the the industry may get confused, especially with "slang"). A dirt pocket is required not just by code, but just by good piping practice alone. The purpose is to collect any dirt or debris that may end up in the pipe during installation. It is especially important when the pipe is black iron because there will be shavings and oil from the threading process. It's not as important when using copper or CSST (flex pipe), but it is still good practice none the less. Also, flashing should be used to keep insulation away from the vent.
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Old 02-05-2011, 04:57 PM   #10
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Shop heater, gas pipe in contact with vent


looks like the electrical line is strapped to the trac pipe. I would move this
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Old 02-05-2011, 07:07 PM   #11
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Shop heater, gas pipe in contact with vent


Quote:
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looks like the electrical line is strapped to the trac pipe. I would move this
Not allowed by code? I can see concern about a spark igniting a gas leak but if the piping is solid and the conduit/wire is solid, what could be the problem?
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Old 02-05-2011, 07:49 PM   #12
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Shop heater, gas pipe in contact with vent


trac pipe is thin. I would worry about the unit vibrating when in operation a maybe rubbing a hole in the trac pipe. May not happen but, you never know. I like to play it safe
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Old 02-05-2011, 08:30 PM   #13
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Shop heater, gas pipe in contact with vent


People used to fill up the hole with building materials found on the jobsite. What's wrong with stuffing fiberglass in the holes?
This is a common and sometimes fatal misconception. Materials have specific purposes. When used for these specific purposes, they do a fine job. Fiberglass, for example, is a fine insulating material. While it's true that the glass itself does not burn, the binders in insulation do. Not only this but glass melts at about 1200* F (649*C)! Actual tests show that fiberglass used as a firestop will melt out in about 5 minutes!

I stand corrected..

:-) Ken
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Old 02-05-2011, 09:08 PM   #14
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Shop heater, gas pipe in contact with vent


UMC on Drip Legs and Sediment traps (dirt legs)

1312.6.1 Provide Drips Where Necessary.For
other than dry gas conditions, a drip shall be provided at any point in the line of pipe where condensate could collect. Where required by the Authority Having Jurisdiction or the serving gas supplier, a drip shall also be provided at the outlet of the meter. This drip shall be so installed as to constitute a trap wherein an accumulation of condensate will shut off the flow of gas before it will run back into the meter. [NFPA 54:7.6.1]

Here in the eastern slopes of Colorado we typically have dry gas.

1312.6.3 Sediment Traps.(See Section 1312.7.)


(This is Georgia's code)

Sediment traps are identical to drip legs that were installed in the piping
system to collect any moisture and trash and keep it from reaching the
appliance. Since gas delivered today is refined through a drying process and
contains almost no moisture drip legs are no longer necessary. To collect any
trash or dust that can be inside the pipe that could cause problems for the gas
appliance.sediment traps are now required to be installed at the appliance.
Appliances requiring a sediment trap is one that operates automatically.
These would include furnaces and water heaters. Gas lights, ranges, clothes
dryers, and outdoor grills do not need a sediment trap.

We don't require them here.. Interesting info..

:-) Ken



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Old 02-05-2011, 10:19 PM   #15
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Shop heater, gas pipe in contact with vent


I happened to notice that there is some kind of flange surrounding the vent pipe at the drywall if you look closely at the photo:



I am also going to ask the contractor that installed the pipe about this situation and see what he says.

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