Sorry I was in a hurry and shot a quick reply.
(This vent was 22 inches high. Tub had slow drainage.)
It could be a number of things but the height is not one of them such as blockage, undersized, a big hair ball in the tub drain
(What are all the ramifications of having a vent this high?)
As long as it's in the specified range as listed in some of the post, "none"
(Could a vent this high impact the drainage of the tub?)
Jerry or one of the other guru's probably answer this better but I don't think height is a question as far as drainage is concerned.
(Also, would anyone say it is a problem with the base flashing for the vent over hanging the valley?)
It would be nice for it to be further out of the valley so it don't collect debris and ice damming and large volumes of water but as long as it's installed correctly it shouldn't leak. Granted this may be the first area that may start leaking when the roof ages.
Jeff, Please forgive for I have sinned and it won't happen again
Not!
