Vapor Lock Kicked In

[Chefwong]

Previous water heater died due to vapor lock....
Been thinking about this as I never did conclude to a root cause
It started one day where we picked smell of the backdrafting gases
Close inspection of the plastic -caps- around the feeds indeed confirmed it was backdrafting
Then in the same week, vapor lock kicked in

Anyhow, while everything was disconnected, I ran the flue brushes, gave it a good vac, etc
New water heater in place for the last 2 months or so. Zero backdrafting issues, etc.

Still scratching my head on this one on what would have caused the backdrafting.
Flue was clean
Everything else being the same/similar...

 

[Fitter30]

Brand and model of furnace ( inside of burner compartment). Sizes of flue wh, furnace and stack / height. Pictures all the flue wh and furnace . Wh and furnace input gas btu's and type of gas.

 

[Sponsor]

 

[Jeff H Young]

Im familiar with back draft but not vapor lock are those the same thing? going to need a whole lot more info to solve this problem that no longer exists.
no mention of whether there is a furnace in this equation or if its in the same area , sharing vents etc. sizes of the vents suffiecient combustion air etc. etc.