Cooktop exhausts through thinwall tube though foundation. rainwater problem

[Odysseus]

The first photo is in the cabinet under the cooktop, There are some black cooking utensils in the background which may confuse the picture, but the bottom of the cooktop exhaust is clearly shown (with the label with barcodes) joining to the flexible tube which is attached to the 4" to 6" stepup converter at the bottom of the cabinet. The 6" pvc drops approximately 15" from the converter to a 90 degree elbow. From the elbow, the 6" pvc tube runs (approximately) horizontally about 30' to the outside (see next photos)

The second photo is the little box we made using extra tiles. The horizontal line crossing the top of the photo is the bottom of the exterior wall with foundation underneath. The cover extends out to keep rain from entering the box.

The third shows the interior of the box with the 6" pvc tube at bottom center.

I attempted to waterproof it with several cans of the spray type rubber sealer but no cigar.

 

[Michael Young]

I still say FERNCO and a street 90 and get rid of the begging-to-fill-up-with-water box

 

[Sponsor]

 

[Odysseus]

And I still do not understand the purpose of or how to use the fernco. Elaboration would be helpful.

My first attempted solution was the same 90 you propose, except that the exhaust tube is 6" and there was not enough room to fit a 6" street 90 between the existing 6" tube and the walkway nearby, and so had to go with a 6" grommet around a 4" tube inside the existing 6", attached to a 4" 90. Was unable to make this water tight.

Next built the box you see in the 2nd and 3rd photo, but also unable to make this watertight using the spray rubber coating. I asked at HD for some sort of sealant to make the box water tight, but no one could suggest anything.

If I could make this box water tight, I believe it would solve the problem. Do you know of any sealer with which I could brush paint the inside and outside of the box, including where it is against the foundation, to waterproof the entire unit?

Thanks.

 

[Michael Young]

redguard does a good job as a paint-on sealant