Potential risk of leaks with inverted top plate install

[chris2879]

I posted earlier today about leaking that is occurring during rain storms in our chimney. The installer is giving us the "run around" so then i began to think about how it was installed. When he installed the liner, he used a flat top plate and turned it upside down, so the clamp was "inside" the flu tile area. He then silicone or epoxied it to the top of the flu tile. He did this because of clearance with the multi flu cap. I figured this was fine not really thinking about it.

However when it is inverted, it is effectively a flat plate over top of the flu tile (mine is 12"x12") with a 6" hole in the middle for the liner. Even though there is a multi flu cap on my chimney, when water gets on this "flat" surface (i.e. wind, splashing), where does it go? I am speculating that some of the water finds its way down the 6" hole in the middle. In the case of an inverted installation, the SS liner slided inside the flat plate collar and then it tightened down by the clamp. There is not a weather tight seal made beween the collar of the top plate and the SS liner. Is it possible and likely water will find its way down between the collar and the liner, dripping all the way down the liner and on to the top of the stove?

When the flat top plate is installed normal way up, the collar sticks up and the liner sides through it with the clamp on the top. With this setup, flat surface of the top plate has a 6" collar sticking up an inch or two. Therefore, when water collects on the flat part of the plate it "has" to run off the side, and can not run down liner.

I attached a sketch to try to illustrate my concern with the inverted top plate concern. Please let me know your thoughts.

Here is a link to my other post with the rust that occured from the water getting in.
https://www.hearth.com/econtent/index.php/forums/viewthread/79650/

 

[begreen]

That illustrates my concern exactly. If necessary I would replace the bird cage on top of the flue before creating a natural downspout for wind driven rain.

 

[chris2879]

I was waiting for your reply! Is the inverted top plate not too commonly used? People who do have it, do they have the issues i am having?

Here's another question, with the inverted installation, the liner is slightly below the flu tile. With a normal installation, it has to come up above the flu tiles a couple of inches. What would be the best way to extend the liner to make up the addition distance?

 

[begreen]

I'm not sure what is going to be the best solution. Did the water just show up with Hurricane Irene? If so, maybe this is an uncommon event. Like cmon start posted, maybe creating a sealing rim with silicone would suffice? There are flue liner extensions, though these are often 18" long. There is a cap system that might work depending on where the liner ends:

http://chimneylinerinc.com/pic.php?pic=quickCap-lg.jpg&cap=Round Rain Cap Top Plate Mount

 

[chris2879]

The first time I did notice it was with irene and then maybe 1 other time afterwards. Even it it only happens every so often, i really want to get it resolved.

I was thinking about 2 options. First, getting a 6.5" diameter of flu pipe and cutting it so it is about 1/2 - 1" tall. I can then silicone that to the existing top plate, this would make a lip to stop the "downspout" effect round the round opening. Or second, i can get another top plate and just install it over top of the inverted flat plate that is there. This way it is effectively extending the liner, and adding rain protection around the flu opening. At worst case, if there is not enough clearance between the top of the "new" flu pipe and the multi flu cap, i could just replace the multi flu cap with a taller one so i have a clearance of >5-6" from the top of the flu to the cap.

What kind of material is the top plate made of, is it sheet metal or aluminum?

 

[cmonSTART]

The top plate is made from stainless steel.

I like the 1/2" ring of flue pipe idea. I bet that will work if you give it a good dose of silicone.

 

[begreen]

+1, good thinking and worth a try.