Heat-Fab liner, clamping dilemna

[precaud]

I'm rehearsing the liner installation, and there's a problem with the topper. As expected, it consists of top plate, clamp, storm collar (bought together as a kit), and raincap. These are all Heat-Fab's parts. Problem is, the clamp is too wide and doesn't fit under the storm collar, where it belongs.

The supplied instructions don't even mention the clamp. Which means the liner weight is unsupported from the top.

I called the dealer and asked what they recommend. He said DEFINITELY use the clamp (which I agreed with), and there will be approx. 2" airspace between the collar and the top plate. Stuff the space between the liner and the top plate hole with rock wool, to "seal" the top.

Now that seems like a pretty cheesy solution to me, and noone in town has rock wool in stock either. I think anything that stops the storm collar from sitting flush against the top plate (as it is designed to do) is a bad idea.

So, the other choice is to put the clamp above the storm collar, which isn't pretty but lets the storm collar do it's job and does provide SOME load bearing up there.

Which do you think is best?

 

[BrotherBart]

Is this section in your instruction manual?

"Install the storm collar directly below the expanded portion of the liner by
tightening the clamp screw. The storm collar will then rest on the cover
plate, supporting the upper sections of the liner system. Slide the rain cap
into the expanded portion of the liner and secure with the four self-drilling
screws provided. (see Fig. 6)"

 

[BrotherBart]

Is this section in your instruction manual?

"Install the storm collar directly below the expanded portion of the liner by
tightening the clamp screw. The storm collar will then rest on the cover
plate, supporting the upper sections of the liner system. Slide the rain cap
into the expanded portion of the liner and secure with the four self-drilling
screws provided. (see Fig. 6)"

Also on the installation portion of their web site they say to call their engineering department if you have installation questions. Take'em up on it.

1-800-772-0739

 

[precaud]

Yup. But why do they sell a kit that includes a clamp then? And the instuctions give you no flexibility on the height of the pipe above the top plate.

 

[precaud]

Also on the installation portion of their web site they say to call their engineering department if you have installation questions. Take'em up on it.

1-800-772-0739

Good suggestion, thanks. I'll follow up on that. But regardless, I'm leaning toward putting the clamp above the collar. Apparently the collar is robust enough to bear the load, as in their instructions.

 

[precaud]

Just talked to a tech at Heat-Fab. Nice guy. Notes from our talk:

The instructions on their website AND that come with the liner are outdated. They don't mention the clamp, which is important for load-bearing.

The recommended arrangement is as given above; top plate, clamp, then storm collar above. This leaves about a 2" gap between the collar and top plate. The 1/4" airspace around the top plate and the pipe is left open.

He said, water will drop off the storm collar and won't go down the hole. "Assuming there's no wind" I said... he chuckled and agreed.

"What about the dead airspace in the chimney that the top plate is supposed to create for the liner?" I asked. He suggested I use the insulated wrap if that was a concern.

He was as unenthusiastic about stuffing the hole with rock wool as I was, but said it wouldn't hurt to do it.

Putting the clamp above the collar was also OK in his view. Basically, choose the arrangement that works best for you.

I still say this is a cheesy arrangement for such a high-tech venting system.