Stack questions

[Bricklayer]

I just received my 2.5 x 10 CDL Venturi on Wednesday. We are installing the stack tomorrow. Just had a few questions before I go and get all the supplies.

1. The cap that came with the evaporator is a rope operated cap.
Obviously I’m going to use stainless wire cable for it. But where do I run the rope ? Drill a hole in the roof ? Seems kind of silly. Is there a different way of doing it ?

2. The kit came with a roof Jack and a top flashing. I’m used to installing double walled chimney pipe and I usually high temp caulk around the roof Jack and then install the top flashing. Then caulk again. Don’t really have this option with the single walled pipe since it will be Probley above the temp rated for the high heat caulking. What is a good way to seal it. ?

3. Do I need to pre drill the holes for the stainless pipe or will stainless self tappers be ok for connecting the pipe. ?


For some reason I can not post pictures. Keeps saying upload failed when I try to upload pictures.

[maple flats]

I ran a medium gauge SS wire rope for mine. I have a steel roof and I just, from underneath used a nail very slightly larger and the wire rope diameter, and punched 2 holes, just out past the roof jack. It worked perfectly and I never detected any leaks getting thru. If you don't have a steel roof, I'd likely punch thru the outer edge of the roof jack from underneath before you install the jack.
On mine I then attached the opener wire rope at 1 side of the arch and th closer wire rope to the other side. But on mine I got a defective flip top cap that was welded in the wrong position (at a good price), so I attached the one side to the arch with just the right length of wire rope, and on the other side i had to attach the wire rope to hold the cap open. If that hadn't worked so well I was going to cut off the rull lever , reposition it and reweld it, but it was not necessary. The issue was that the lid would go too far over and I had to get up on the roof to flip it back, the way I did it solved the over travel problem.
My old 2x6 with flip cap worked perfectly, pull one rope it opened, pull the other it closed.

[Bricklayer]

Thanks Dave,
I do have a metal roof on our shack. So I’ll try your method.

What about sealing the stack at the roof flashing. Is there any type of silicone that everyone uses. I have the high temp RTV chimney silicone. But it’s only good for 500 degrees.
I’m sure the temp will be a lot higher then that.

[amasonry]

if you look around you should be able to find some high temp silicone rated for 2300 degrees.

[aamyotte]

For the hole where the cable somes through you can put a bead of sealant in an arc around the hole on the high side of it. That way water running on the roof surface will be deflected around it.

[Bricklayer]

I ended up using a 1/8” stainless cable and since our stack is about 24” from the gable end it worked out that I just put a small pully on the side of the soffit and can pull straight down and cap opens all the way. Works great. No need for a hole.

I’ve looked everywhere for a high temp silicone or exterior sealer that is above 800 degree rated and they don’t exist unless you want to spend $242 for a caulking tube of it.
CDL put some sorting Grey sealer on my roof Jack. So gonna see if they will let me in on their secret.

[ebliese]

I'm in the same boat-single walled pipe through the roof and nothing I have tried works to seal the storm collar. One fellow on here recommended chimney sealant. He found some on amazon/ebay and is good up to 1500*F. It worked for him. I haven't found any so far. I've been considering Smoky Lake's double walled exhaust (different than concentric exhaust) but you already have a roof jack and stack cap so that probably isn't an option for you.

[Pdiamond]

Daniel, for safeties sake I believe you should be using double wall pipe through the roof. This is because of the high Temps and reduces the risk of a fire.

[tcross]

i haven't been able to find anything with enough heat resistance to last. what i do is once i'm done the season, i put a bead of regular silicone sealant around the storm collar. after the first time i use it when the season starts, it burns off, so it's doesn't work during the season, but it does work during the 9 other months.

[ebliese]

Daniel, for safeties sake I believe you should be using double wall pipe through the roof. This is because of the high Temps and reduces the risk of a fire.

Sorry, this was my fault. I should have mentioned it's a metal roof, no underlayment. I had to take out a section of a purlin in the pole barn (or really, lean-to addition to the pole barn) to accommodate the high stack temps/provide good clearance to combustibles.