double wall telescoping pipe questions (fubar?)

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bag of hammers

Minister of Fire
Jan 7, 2010
1,442
Northern ON
Hi all - new here - lots of colourful posts I see - so I'm going to dip my toe in the water and ask a couple questions.

I have a new Osburn (1800) that I've installed and fired up (first time last winter) in a new addition. aside : I've read some complaints around the web about these stoves, but mine works like a charm (easily toasts us in a 1000 sq ft area) - but i digress.

Anyway, my issue: I run a single length of the telescoping pipe straight up from the flue collar to the chimney adapter / insulated chimney(cathedral box support). A single section / chunk makes the trip.

I typically run the stove on weekends (when I'm out at the camp). The stove pipe expands / contracts when hot / cold as expected (guessing about 1/8" or so) and the tele pipe 'slips' just a bit to allow for the expansion. Which was kinda the intent. works like a charm. Then I installed a flue probe - extremely easy and works well - it is currently set at the recommended height according to instructions (approx 18" above the flue collar). But - this recommended height happens to be within the part of the telescoping pipe that "slips". So when I fire up the stove the pipe expands, and voila - it pinches the probe (not killing it, just binds it up a bit). Made me cringe a bit at first - but when things cooled off I could easily slide out the thermometer - no visible damage to pipe or probe. Still worried about it though.

Should I be ditching the telescoping pipe? Was it a mistake? This is a straight vertical run up thru the ceiling / roof.

Should I have installed the probe closer to the stove top (below the part of the pipe that 'overlaps' - but also below the manufacturer's spec)?

Should I even be worrying and wasting your time here?

I think I goofed but not sure if I should be freaking out or retrofitting anything

One last (related) question - the insulated chimney (supervent) hangs down thru the cathedral box / hanger approx 12" inside the room - not sure (from a "typical" or aesthetic point of view) if I should push it up to where it only hangs inside a couple inches? I think I only did this to keep the stove pipe adapter at the bottom of the supervent pipe farther away from the steep sloped ceiling

sorry for the long post - any feedback is appreciated.

Thanks
 
I have the same telescoping double wall pipe setup as a single piece from stove to ceiling. You are supposed to put three screws in at the bottom of the outermost shell to "pin" the slip piece in place and not allow that 1/8" slip to occur. My duravent came with the screw holes/slots already in place.

With the telescoping pipe piece pinned in place your probe meter will not be subjected to the pinch.
 
Yeap, put screws in the telescoping joint, that's how it should be anyway. It will find someplace else to expand to.
 
It works great to fit all flue stack situations.
Mine is by Selkirk Metalbestos.

Other brands also make it.
 
jtp10181 said:
Yeap, put screws in the telescoping joint, that's how it should be anyway. It will find someplace else to expand to.

thanks jtp and others - so there's no concern if the expansion lifts the entire chimney just enough that the insulated pipe's support (ring) doesn't rest on the cathedral support box any more (it gets "lifted" by the expanding pipe and now all the weight bears down on the stove..)?

apologies if I'm over-thinking this - just want to understand as much as I can - thanks again all...
 
When you install the telescoping pipe there is no way to hold everything so extended that you don't have room for the little bit of expansion. That little cheezy SS adapter that pops into the ceiling support box will certainly allow plenty of slop to prevent the actual chimney from being jacked off of its support. You are correct that the stove isn't made to support the chimney. The ceiling support box supports the chimney and the stove supports the black connector pipe.

In an extreme case I would actually expect the expanding connector pipe to exert force on the ceiling box and lift the ceiling before it would shove the silver class A out of the ceiling support box. See the class A pipe is supposed to be attached to the ceiling box independently, mine twist locks to the ceiling support box.
 
Highbeam said:
When you install the telescoping pipe there is no way to hold everything so extended that you don't have room for the little bit of expansion. That little cheezy SS adapter that pops into the ceiling support box will certainly allow plenty of slop to prevent the actual chimney from being jacked off of its support. You are correct that the stove isn't made to support the chimney. The ceiling support box supports the chimney and the stove supports the black connector pipe.

In an extreme case I would actually expect the expanding connector pipe to exert force on the ceiling box and lift the ceiling before it would shove the silver class A out of the ceiling support box. See the class A pipe is supposed to be attached to the ceiling box independently, mine twist locks to the ceiling support box.

Interesting - in my case the SS chimney rests on a support ring (attached to the outside of the pipe about 12" from the bottom end) - the ring rests on the bottom of the ceiling box with the 12" of SS pipe extending thru the bottom of the support box and down into the room. The adapter screws into the bottom of the SS pipe. Guess I'm just regurgitating stuff you already know. I could get under the pipe and push the whole works up - I didn't even know you could have a setup where the pipe locks onto the support box. or an adapter that pops into the support box. i can see how that would put the stress on the ceiling in the extreme case. As you can see, still learning here - thanks for the additional details
 
Sounds like you have a strange pipe system. The class A comes through the support box and has some sort of a clamp on it that rests on the support box, holding the weight of the chimney.

I would just screw the telescoping together and see what happens. Probably nothing will happen :)
 
Hammers, do not ditch the telescoping pipe. It provides closer clearances and lasts longer than single wall. Screw the pieces together as suggested by Highbeam and jtp.

Additionally, I'm confused by the clamp around the chimney which is used to support the chimney inside the support box. Did you install this clamp or was it done at the factory? If you installed it, are you certain it was installed correctly? If you are able to loosen the clamp and move the chimney up or down as you wish, it seems to me that it would not support the full weight of the chimney. Are the chimney support box and chimney pipe both made by Selkirk? Are those two items engineered to go together as part of the Class A chimney system?

Something in your installation appears to be out of the ordinary but I am unable to understand what it is. The "problem", if there is one, appears to be in the connection between the support box and the first section of chimney. I am unable to be more specific than that. Perhaps others having much experience with the Selkirk products will provide more specific guidance.

Best wishes,

John_M
 
Going by the description I have the same ceiling support box as the OP. It sounds like he did everything correctly. What I don't have is the single piece of telescoping pipe. What i dont understand is how he is going to adjust his class A pipe in the support box now, the clamp he is refering to is inside the ceiling supprt box below the roof penetration and the storm collar.
 
Yeah it makes perfect sense to me. That's exactly how the Duravent pellet pipe support boxes work. Does not sound like the best idea for a much heavier Class A system, but if it has not fallen through the ceiling yet... The adjustable roof supports work in the same way, from Duravent. You clamp it around the pipe and it has wings on it that you can screw to the floor, roof, whatever. It supports the whole pipe system. Then you just punch the Class A right through the ceiling and put a trim ring around, no box needed.
 
thanks all - sorry for delay posting back here again (been away from the desk for a bit)

to answer some questions - the whole setup is from Selkirk . The chimney is their Supervent 2100. My original post was probably a bit confusing - but essentially there's a ring that fits around and attaches to the outside of the insulated pipe (with 4 short screws that go thru the ring into the outer wall of the pipe). The pipe then slides down into the box and thru the bottom until the ring comes to rest on the bottom of the box. The ring supports everything. Part of the pipe extends out the bottom (how far depends on where the ring was attached) So nothing is really clamped to the box - its the ring screwed to the pipe and the ring is what rests on the bottom of the box. That's why I mentioned I could push the whole thing up - like just get under it and lift everything - the ring lifts off the bottom of the box. As mentioned by Cre73, if I did want to adjust this at all (just so I don't have as much insulated pipe extending down into the room), the ring is inside the box so I would have to lift everything out the top, remove the ring, re- attach the ring a bit lower on the pipe, and drop it all back in again. I think this would be a lot of trouble just for appearances - not sure it I want to go to the trouble. Just that the current 12" of insulated pipe sticking out the bottom of the box seems a bit much (based on what I've seen in a couple other installs). Probably over- thinking this.

Also this is a 6" flue. From the stove to the insulated pipe I have a single telescopic double wall pipe - connects to the bottom of the insulated pipe with a stove pipe adapter that screws onto the insulated pipe. Might be more of a worry if it was a larger stove / flue (heavier pipe?).

This is all the supervent stuff sold everywhere in Canada - Tractor Supply, Canadian Tire, etc. According to Selkirk, this ring / box could support something like 15 feet of insulated pipe if I recall (and I have 9').

I really should get a new camera and save everyone the grief of reading my confusing descriptions. But thanks for all the replies and sanity checks.
 
Made perfect sense to me the first time :)
I see why not many people have heard of it though, if it only supports 15ft of pipe. The other support methods mentioned in this thread are usually good for 50-60ft of pipe, so they are probably more common, just to be safe. I'm sure your setup is fine, esp with only 9' of pipe.

So, did you put screws in the tele pipe yet?
 
I have a similar install and used the same components. OP's dilema of whether or not to adjust the 12" of insulated pipe hanging below his ceiling depends on his ceiling pitch and how far cathedral box penetrates. IIRC installation instructions provide a chart to make this determination, although you presently have more than is likely required.
The clamp that holds insulated pipe within cathedral support box is adjustable, tightened by nut and bolt only. Sounds like you could slide the insulated pipe upward (improve the esthetics) and eliminate interference at temperature probe.
Just remember...3 screws at each connection and adjust the storm collar when finished.
 
jtp10181 said:
Yeap, put screws in the telescoping joint, that's how it should be anyway. It will find someplace else to expand to.

I was told that the expansion of a slip joint was there to allow for expansion. The installer said that they don't use screws, but take a hammer and make a peen/dent while they are together to prevent them from slippingapart inside the chase/chimney.... The overlap on mine appeared to be three or four feet.

Is this "dent" procedure used elsewhere?

Bill
 
billjustbill said:
jtp10181 said:
Yeap, put screws in the telescoping joint, that's how it should be anyway. It will find someplace else to expand to.

I was told that the expansion of a slip joint was there to allow for expansion. The installer said that they don't use screws, but take a hammer and make a peen/dent while they are together to prevent them from slippingapart inside the chase/chimney.... The overlap on mine appeared to be three or four feet.

Is this "dent" procedure used elsewhere?

Bill

never seen, or would want to do, a dent method... due to said expansion, the dent could work its way out... 3 screws are what is required by all install manuals I have ever read...
 
jtp10181 said:
Made perfect sense to me the first time :)
I see why not many people have heard of it though, if it only supports 15ft of pipe. The other support methods mentioned in this thread are usually good for 50-60ft of pipe, so they are probably more common, just to be safe. I'm sure your setup is fine, esp with only 9' of pipe.

So, did you put screws in the tele pipe yet?

yeah i do recall the install info with the cathedral box specifically talking about the max length for this kind of support - I think the instructions were specific to the size of pipe (6" in my case). I think I saw something about scaling the length down with a larger diameter pipe, which I guess would make sense - but I don't know how it could be any shorter than what I have (I just clear the peak by the 2' required).

my setup is in my camp - weekends only right now - so I haven't made any changes based on suggestions here yet. I have to remove the tele pipe and move the stove over (i'm making a new hearth pad) so I can add the screws when I put it all back.

thanks very much everyone for the feedback
 
billjustbill said:
jtp10181 said:
Yeap, put screws in the telescoping joint, that's how it should be anyway. It will find someplace else to expand to.

I was told that the expansion of a slip joint was there to allow for expansion. The installer said that they don't use screws, but take a hammer and make a peen/dent while they are together to prevent them from slippingapart inside the chase/chimney.... The overlap on mine appeared to be three or four feet.

Is this "dent" procedure used elsewhere?

Bill

Also, any chimney that is in a chase/chimney will be class A pipe and won't have slip joints. They didn't bury black stove pipe in a chase did they? Wouldn't surprise me with their dent method.
 
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