Rheem 90+ chimney condensation drip
I have a 10 year old Rheem 90 propane furnace in a rental home. About 8 years ago, the furnace died on the tenants and I called in a repairman and he said it was leaking down the PVC chimney from the roof. There was standing water on top of the furnace, dripping into a small hole into the furnace down onto the burner tray. So I went on the roof and caulked everywhere.
The thick PVC pipe (~6 inches round) goes straight up through the ceiling about 4 feet, with one connection with tight purple glue.
Again, after a cold winter and continuous use of the furnace, it failed again. There is no way the water is coming from the roof, I can only assume it is condensation dripping on the outside of the PVC chimney.
So I did an easy fix. I tied 3 rags on the chimney to collect the dripping water. I've replaced the rags every couple years and have had zero problems since doing that.
I'm thinking of selling the house to the current tenants and would like to find a better fix for this. Any suggestions?
Would making an L connection going out to the side of the house work?