Wall thimble help

[colin.mitchell.129]

In the middle of installing my beacon morris 45k btu garage heater. I'm horizontally venting with 4" cat iii pipe. Just making sure I get the wall thimble correct. It says on the sticker that it needs 8" clearance to combustibles. Essentially it's a 4" pipe going through a 6" pipe(thimble) so does that mean I need 8" clearance from the edge of the center of the thimble? The wall I'm going through is 16" on center studs with 3/4" wood paneling, fiberglass insulation, plywood, then vinyl siding. I was planning on going through the middle space between 2 studs and using a 6" hole saw all the way through. Secure the the thimble on the inside by screwing to the wood paneling and on the outside cutting away the vinyl in a square so the thimble sits flush to the plywood then screwing it down. Does this sound correct, or do I need to make bigger clearances?


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[colin.mitchell.129]

Can anyone help me? I've read hours and hours of older topics on here and can't find the answer.

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[Mike007]

These type issues can be difficult to answer. I think you really need to reach out to Z-Flex for clarification. Based on the information provided, I would say you need 8" from the edge of the pipe in any direction to a combustible.

 

[colin.mitchell.129]

These type issues can be difficult to answer. I think you really need to reach out to Z-Flex for clarification. Based on the information provided, I would say you need 8" from the edge of the pipe in any direction to a combustible.

That's what I would think but there's not even 8" from the pipe edge to the edge of the thimble flashing.

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[colin.mitchell.129]

I just figured as many of these types of heater install topics on this forum, surely someone has used a cat iii thimble through a standard wall.

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[finn]

The reference to enclosed is if the pipe is in a combustible (wood) chase, like a wooden chimney.

The unenclosed is if the pipe is ajacent to a wall or ceiling.

Thimbles would normally provide an airspace around the pipe and all that I have seen require that there be a 1"-2" air gap around the thimble center hole.

 

[CNGsaves]

Key is NOT to pile insulation right next to pipe/thimble you just put through ceiling.

Think you ought to have "buffer" area around even Cat 3 pipe once it goes through ceiling so that insulation doesn't get pushed right up next to pipe. This could be something as simple as wire mesh cage to add space around the pipe. Could also devise a . . . "Pipe in a Pipe" . . so that insulation can't sit right next to your vertical flue pipe.

 

[colin.mitchell.129]

Key is NOT to pile insulation right next to pipe/thimble you just put through ceiling.

Think you ought to have "buffer" area around even Cat 3 pipe once it goes through ceiling so that insulation doesn't get pushed right up next to pipe. This could be something as simple as wire mesh cage to add space around the pipe. Could also devise a . . . "Pipe in a Pipe" . . so that insulation can't sit right next to your vertical flue pipe.

I'm going horizontal through a wall. And isn't the thimble the "pipe in a pipe?" It's essentially a 4" pipe going through a 6" pipe. I'm just trying to figure out what clearances are needed from the thimble to everything else.

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[colin.mitchell.129]

The reference to enclosed is if the pipe is in a combustible (wood) chase, like a wooden chimney.

The unenclosed is if the pipe is ajacent to a wall or ceiling.

Thimbles would normally provide an airspace around the pipe and all that I have seen require that there be a 1"-2" air gap around the thimble center hole.

Thanks for the clarification. The 4" pipe inside the thimble (6" pipe) is that airspace your referring to? So the wood paneling, insulation, and osb can be touching the outside of the thimble, or I need space around that?

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[CNGsaves]

My bad, I thought you were going vertical.

Think you've pretty much got it whipped if your thimble is appropriate.

 

[colin.mitchell.129]

My bad, I thought you were going vertical.

Think you've pretty much got it whipped if your thimble is appropriate.

No worries. It should be as much as this cat iii cost. Lol

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