Horizontal Category iii vent ?

[manwithtools]

Horizontal Category III vent ?

I've got a new 60K unit heater and I want to vent it horizontally out the side wall of my metal building. I've sourced all the Category iii vent pieces I think I need, but I'm questioning if I need a thimble?

The thimbles I'm finding all seem to indicate they are not required for non-combustible walls (last I checked the metal qualifies as non-combustible ). I'm just curious how I'll seal the Cat iii pipe to the building wall to prevent water leaking into the interior without the use of a thimble?

Any thoughts beyond good silicone caulk?

 

[SuperD]

The Cat III requirements get a bit confusing, same thing here in Canada. I finally just phoned the inspector himself, and was pleased with his suggestions. For a wall thimble he explained to me to run the single wall Cat III through a piece of double wall B vent which allows one inch clearance , or to use a thimble that allows the Cat III to run through it. I would suggest to call your local gas inspector, just explain that you want to complete the install correctly. You may be pleasantly surprised on the help you receive.

 

[manwithtools]

I understand how a thimble works. I'm not confused by Cat III, I just don't see a good way to weatherproof a metal building wall penetration without a thimble. Probably a mute point now as I just ordered a thimble.

I don't think my gas inspector cares if water comes into my building as much as he cares my installation does not cause a fire. Thanks for the input just the same.

 

[SuperD]

I see I missed you question about the specific point that you have a metal building, my sincere apologies.

 

[manwithtools]

I see I missed you question about the specific point that you have a metal building, my sincere apologies.

No worries, I was a bit reactive in my response. Sometimes I get impatient and answer too quickly.

Thanks for responding to my post. I am going to be talking to my local propane supplier and will ask their opinion - not an inspector, but certainly folks that should have experience with this type of installation.

 

[13.2kv]

I would just use high temp silicone, you'll need it anyways to seal the pipe to the thimble outside, you may also need an adapter ring for the thimble, my thimble was an inch bigger diameter on the outside piece of the thimble for some reason.