I have a small Schrader wood stove in my shop that I need to get a flue installed. I used the stove at an unattached garage with wood and asphalt shingle roof for 8 years. I don’t know for a fact, but almost positive I used the 5’ of 6” single wall stove pipe with 2 adapters bringing it down to 4” that was attached to a section of 4” double walled Class B pipe with a cap on top of that. The stove worked great and no problems ever with smoke or not getting a good draft. The new location is an unattached metal shop building that is insulated but still just a single sheet of metal roofing. I’m wanting to go straight up and through the roof with the same kind of setup as before, but now I have people telling me that won’t work. Does anybody have any experience with venting this way? I can’t absolutely remember what the 4” pipe was at the initial install, but I’m pretty certain it wasn’t a Class A pipe. For one thing, I didn’t spend NEAR that amount of money to install that a Class A pipe would cost. (I am going to install a Dektite hi-heat roof boot on the top side of the roof.)
Sounds like you are very lucky that the first install... 1. Worked. 2. Didn't burn the place down. Just because you got away with it once is not a good reason to push your luck again...a few pieces of 6" class A chimney pipe are not that expensive...way less than the insurance deductible on the building most likely, if the insurance company will even allow a wood stove to be installed there at all...most/many won't in a shop/garage. If you have Menards in your area, they sell the Supervent brand very reasonably...if no Menards, Lowes or HD would be next I guess...or a mail order chimney supply place...
Class "B" vent for a wood stove? Sheesh! Lucky you aren't telling us about a tragedy! B vent is for gas appliances. Class A vent is for solid fuel such as wood, coal, oil. B vent has an aluminum liner where A's liner is stainless. Typically, CTC (clearance to combustibles) for B is 1". For A 2". The difference is size between a 4" and 6" pipe? 4=12 1/2" and 6=28 1/4" That's constricting the venting quite a bit. You decreased it by over 50%!!! Rule of thumb.....never downsize the woodstove flue....whatever the size of the collar is on the stove, stay with that all the way. In addition, it appears that the pipe attached to the wood stove is galvanized. this is a big "no-no" for wood stoves. The galvanized can off-gas phosgene when it's heated up. Nasty stuff. Black stove pipe is the way to go. It is good that you can go straight up with the vent. Myself, I would use single wall black pipe up until the roof penetration where it would be transitioned to a supported Class A vent. You'll probably need two lengths of class A to satisfy the "2-3-10 rule".... "This rule means that your chimney's shortest side needs to be at least 3 feet above the roof penetration, and its top has to be 2 feet higher than any part of the building that's within 10 feet." I hope this helpsa without creating too much confusion. "Clear as mud" huh? Thanks for joining KenR Looks like the workshop will be a nice place to hang out.
Your advise to to transition to Class A vent meaning transition to 6” double or triple wall pipe?? How do you transition between the single wall black pipe and the Class A vent? I’ve not been able to find any transition pieces without very expensive boxes designed for going through ceilings/attics/wood roofs. And by “2 lengths”, do you mean 2 - 3’ lengths?? I was trying to stay with single wall pipe in the shop for the extra radiated heat and to keep the expense down. Thanks for the reply.
If you run single wall up to the Class A that is in the support box, it'll fit right inside without any transition piece. You will have single wall pipe all the way to the ceiling (close enough) for your heat gain. Being the run is straight up, probably a key damper in there also. Crimped ends of the single wall should always be down to the wood stove. The lengths are typically 30" or 36"....those are the sizes I was referring to. Here is an image of the class A but in a shorter length.
The ceiling support kits I am familiar with come with the single wall pipe (or double wall pipe) to class A chimney transition piece...
https://www.menards.com/main/heatin...tove-pipe-adapter/jsc6ase/p-1444453727027.htm https://www.menards.com/main/heatin...4-c-6894.htm?tid=-7212076546439400440&ipos=29
Yes sir, I stand corrected. Thank you. When I though about it, I remembered sliding the first section of Class A down into the support and building up from there. Then, down into the stove room and built up with single wall pipe to the support. Of course, the class A would be on the high side of the ceiling support I bought..... Supervent® 6" ID Class A Double Wall Decorative Ceiling Support at Menards® But I'm pretty sure I "fashioned" my own adapter to connect the black pipe to the bottom side of the ceiling support. I should have bought this instead of "fashioning" one.... ......... Supervent® 6" ID Class A Double Wall Stove Pipe Adapter at Menards®
Took all the advice and got new 6” stove pipe and 6” Class A double wall pipe and high heat roof boot ordered and on the way. Thanks so much - Merry Christmas!
