Smoke from pipe clamp screws

[zerowkul98]

Hi everyone!

My cab50 was moved due to annaddition put on the house. The pipes to the wall have anbuilt-in clamp devoce, but now when I tighten them even to a spot where there is the least bit of compression to hold them together, they make a pop sound and are super loose again. I got some traditional pipe clamps on them, but i smelt smoke at startup. I read old threads and did what they read, got an LeD lightnon the area and i see smoke whisping from behind those screws. I replaced all rubber gaskets last year, cleaned the pipes well and was ready to put the black caulking that the installers used on the pipes, but this time fill around the screws and pipe seams.

Thoughts?

 

[SidecarFlip]

What brand is the venting? I cannot see it in your picture. With any pellet venting, using sheet metal screws to secure the sections is a big No No. the screws will penetrate the inner stainless liner and cause exhaust leakage no matter what you attempt to clamp the pipe sections with. You might try removing the screws entirely and wrapping each joint with foil adhesive tape but me thinks you already screwed the pooch. If you had it installed professionally the first time and the installer used screws, the installer didn't know what they were doing. Screwing sections together with a conventional wood stove works because the draft originates from the chimney flue. Not so with a pellet stove as the combustion blower is pushing the exhaust out so any perforation of the inner liner will cause leakage.

Pellet venting interlocks and has internal gaskets to prevent exhaust leaks.

My suggestion to you (though you won't like it) is replace all the interior venting with new same manufacturer venting and refrain from screwing it together. Twist lock it and apply foil adhesive tape over the joints, or, replace ALL the venting with new, either Selkirk or Simpson Duravent. Keep in mind that neither will interchange with the other. each has their own proprietary locking design.

No matter what you do, you have already compromised the inner stainless liner and no amount of clamping or sealing will eliminate your issue entirely.

Thought I'm not affiliated with them, I suggest (broken link removed) They carry a huge selection of venting from both Selkirk and Simpson and their prices are good too.

 

[zerowkul98]

Thanks for the reply. Those arent sheet metal screws. Those are screws that tighten an internal-pipe clamp device, exactly like the one you see on the left that i added, but smaller.

 

[tlc1976]

By the picture I’d say the brand is Ventis. Not familiar with that brand but this looks like the instructions.

(broken link removed to https://www.rockfordchimneysupply.com/pub/media/wysiwyg/pdf/Rockford%20Pellet%20Vent%20Instructions%20Manual.pdf)

 

[mtnbiker727]

As SidecarFlip said, you've punctured the inner liner. The Duravent PelletVentPro pipe that I have does come with screws for certain pieces (the expandable sections), but they are short enough that the head will be tight against the outer layer before puncturing the inner liner.

I chased smoke for a whole season before I figured out the "professional" installer had used screws that were too long and had punctured the inner liner in several places (see photo). The installer also screwed a 6 inch pipe into the back of the stove instead of using an appliance adapter. You can see the mess I made trying to stop the smoke from coming out everywhere.

I ended up calling Duravent tech support and got all new pipe and an appliance adapter. I used the red RTV goop on the inside of all my seams and did NOT use the Duravent supplied screws because I'm afraid of repeating the problem. Then I used Sharkbite silicone tape (available at Lowe's) to tape the cleanout T, because it didn't seal tight enough and still let smoke through.

 

[zerowkul98]

Guys, no screws are going “into” the pipe. Look at this poc and u can see the built-in adjustable clamp that the pipe has per it’s design.

 

[SidecarFlip]

Not at all familiar with that brand. In fact I've never heard of it until now. My only suggestion would be get a roll of foil adhesive tape (as suggested above) and wrap the joints when the pipe is hot so the tape conforms around the clamp screws readily. Other than that, I'm fresh out of ideas.

 

[rich2500]

sounds like the clamps are stripped and no longer get tight, hard to tell from the pics but it looks like a standard hose clamp that goes in the channel on the pipe so maybe you could replace the clamps with a regular large clamp. Or the company that makes the pipe is Olympia give them a call and see if they sell just the clamps. Here is the phone number

Contact us at 1-800-247-3305​

 

[johneh]

sounds like the clamps are stripped

After years as an Auto teck that is exactly what it sounds like
Tightens so far then slips on a tooth.
(overtightened)

 

[mtnbiker727]

After years as an Auto teck that is exactly what it sounds like
Tightens so far then slips on a tooth.
(overtightened)

Yeah, I've done that trying to make water pipe connections stop leaking in the pasture. That explains the popping sound he's hearing. Once you've done that, it's time for a new clamp.

Alternatively, you could get that as tight as you can get it without it popping, and then wrap Sharkbite tape over it. It's super stretchy, self adhesive, heat resistant up to 500 degrees, easy to cut off, and doesn't leave any sticky crap all over your pipe.

 

[SidecarFlip]

...and all these years I was under the impression that only Simpson and Selkirk made double wall venting for bio mass stoves. learned something new. I don't much care for the interlock design candidly.

 

[Mt Bob]

That is the appliance adapter. Most that use a clamp have a replaceable seal inside. Appears this part number has been discontinued, perhaps it does not have the internal seal? Use silicone sealer, then slide it back on.

 

[ffcls16]

What did you figure out? Mines doing the same things this year?

 

[tbear853]

Those clamps will over time, strip a slot in the band and this the result. It's around the thicker steel pipe exiting the stove, that pipe heats first, expands and the band clamp suffers. If you can, replace the band clamp itself or for temporary use, expand it and add a shim between the band clamp and the pipe. At least it will work a different slot in the band ... temporary fix.

 

[ffcls16]

Those clamps will over time, strip a slot in the band and this the result. It's around the thicker steel pipe exiting the stove, that pipe heats first, expands and the band clamp suffers. If you can, replace the band clamp itself or for temporary use, expand it and add a shim between the band clamp and the pipe. At least it will work a different slot in the band ... temporary fix.

Replaced the inside seals, works like a charm. Thank you though