Another garage heater vent question.

[tshelton1]

I have read many articles on this site but this will be my first time posting. I am installing a Mr. Heater 80k btu garage heater in my detached block garage and have a question about venting.

I would like to vent horizontal out the block wall because it would be easier and there would be no combustible material to pass through. The manual says for horizontal venting I need to use class 3 pipe. Is there any reason I couldn't use b-vent double wall pipe. I live in WV so there will not be any building code inspection. I plan to slope the pipe down 1/4" per foot and disassemble after every winter to inspect for condensation or damage.

I have called around and nowhere around me sells cat3 4" vent. I found it online but it is crazy expensive. I just wanted to see if anyone on here new of any problems I would have if I used b vent and a thimble to pass through the block wall. Thanks in advance!

 

[fitter30]

Here's a good article about the differences and why. UL and the manufacturer write these specs for a good reason your health.
https://www.linkedin.com/pulse/category-i-vs-iii-venting-eric-irmscher

 

[pbon]

It was allowed under code until a few years ago and there are probably many still using it. I don’t think anything bad will happen anytime soon. Inspect it every year. I am in a city that has inspectors so I used the expensive double walled stainless.

 

[Showkey]

CAT III will last your life time and then some, B vent in a horizontal install will not.

Depending your install distance, CATIII should be available on line for about $200.

https://www.menards.com/main/heating-cooling/venting/high-efficiency-appliance-venting/c-9520.htm

CatIII is single wall stainless.

 

[Natty Bumppo]

B vent was used for a long time, and some companies that sell Mr. Heaters are still selling horizontal vent kits that are B vent. I just installed an 80,000 BTU Mr. Heater using 4" Saf-T-Vent class III vent and the parts came out to just under $300 for a 6' run...that included shipping. Bought it all at Menards. Shipping was reasonable and fast.

The manual calls for Class III vent....you want to use B vent.

The manual calls for 1/4" per foot up and out...you're going to do the opposite.

I guess it depends on your run, but if I were you I'd just do it right the first time You won't have to mess with it every year. And you're talking maybe $150 more than B vent.

 

[tshelton1]

Thanks for all the replies. After reading the article it looks like double wall b pipe would have the possibility of leaking since there are no seals on the pipe? From what I've read I should be able to run pipe right through the block and motor it in without a thimble since its not combustible. Possibly put a collar over it for looks. Anything I'm overlooking?

I'm off to find somewhere that sells a 1" stab riser so I can get the gas company to install my meter. Wish me luck!

 

[Showkey]

^^^^^^^^. The B vent concern is corrosion over the long haul. Don't know the complete history of my setup, but the B vent was literally paper thin when I purchased a used home.

 

[tshelton1]

So I got my gas line buried and the gas riser and meter base installed. Now I just have to wait for the gas company to run their line. I plan to hang the heater one evening this week and hopefully run the vent next weekend if everything goes as planned.

I have been thinking about scratching the horizontal vent idea and going with the vertical vent. That way it will be easier to get the parts from local stores. After reading a few articles on here it looks like I could just use b-vent the entire way and a firestop where I pass through the OSB ceiling with a piece of 7" single wall pipe on top of the firestop to keep the insulation back. I know b-vent needs a 1 inch space to combustible material. Would a 6 inch hole be sufficient then mount the firestop to the ceiling. Do I need anything to seal where the b-vent slides through the firestop? It may make better since to me after I see the firestop.

 

[gmtech]

I installed my 80k heater late last fall. I too ran into a problem finding any cat. 3 vent locally. As a matter of fact, everywhere I called acted like I was from outter space when I mentioned cat 3. Not just box stores, local heating and gas companies. They all acted like they had never heard if such a thing. "B vent is what you're looking for" No, no I'm not. I ended up ordering all my cat 3 supplies online for about $200. That was an appliance adapter, 5ft of pipe, wall thimble and a cap.

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