Garage heater pipe clearances

[Ntandro]

To begin with I have searched and searched and was not able to find an answer so here goes. I am installing a 50k mr heater in my garage. I am doing a horizontal vent. Everyone I know vented with standard b vent horizontal . I realize that is not correct so I opted for the stainless class III vent kit. B vent clearance to combustibles is 1 inch. The stainless class III single wall also says 1 inch. This does not seem correct to me considering the single wall will get much hotter. Am I missing something here ? Thanks in advance

 

[papp101]

Is class b the double wall? If so, 1" seems correct, as the hot gasses exit the internal pipe, and the outside pulls in the cold air keeping it cooler.

See here.http://www.ameri-vent.com/type-b-vent-gas


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[Ntandro]

Yes b vent is the double wall. But everywhere and everyone says don’t use that for horizontal venting

 

[pbon]

What are you having trouble maintaining clearance from? The stainless horizontal does not get very hot so 1 inch should be fine.

 

[Showkey]

Read the instructions very closely enclosed or unenclosed spaces ..........

Enclosed area is 4”-8” clearance ( like rafter, attic, wall space see the diagram on enclosed)
Unenclosed area or space is pipe in the open space then 1” clearance is ok.

https://hw.menardc.com/main/items/media/SELKI001/Install_Instruct/CatIIIInstallationInstructions.pdf


Note class A is different from class III so do not get them confused, both are stainless.

 

[k-os]

Get a wall thimble to use with the CAT III vent. That will satisfy the combustible clearances.

 

[Showkey]

Get a wall thimble to use with the CAT III vent. That will satisfy the combustible clearances.

That only satisfies the wall penetrations ......... clearance to the entire vent system still has to be observed.

 

[k-os]

That only satisfies the wall penetrations ......... clearance to the entire vent system still has to be observed.

Right, I should have expanded to say that the thimble will handle the clearances through the wall.

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[Ntandro]

Yea I read them and 1 inch is what I saw. But didn’t seem right because b vent clearance is 1 inch and it’s double wall. So why would double wall b vent and single wall stainless have the same clearances

 

[Bretny]

Why second guess the manufacturer of the pipe? Its 1in clearance use 1in clearance.

 

[pbon]

Again, what do you need to have closer than 1 inch?

 

[Ntandro]

Nothing is closer than an inch. And why question the manufacturer? Take a look at their manuals and you’d know why. If it doesn’t make sense I look for further answers

 

[pbon]

Let us know what you find out, but it sounds like there is no problem you need help solving and this is more of a theoretical question. Have you tried Google? Installation manuals are not always accurate or well written.

 

[racin72charger]

What I’m doing is b vent through the wall via a thimble and vertically once it’s outside past the peek of my roof. No way in hell am I going to cut a hole in my steel roof.

 

[Bretny]

A metal roof is actualy easier to patch than shingles. Idk why people make such a big deal about it. There pannels, remove the screws and it comes right off.

 

[pbon]

What I’m doing is b vent through the wall via a thimble and vertically once it’s outside past the peek of my roof. No way in hell am I going to cut a hole in my steel roof.

What you are doing probably is not to code since it appears the exhaust is horizontal until outside of the building and code requires double wall stainless. But code does not matter to many people. Until 8 years ago, code allowed horizontal b vent.