gas hot water temperature/pressure relief valve issue

[gmeek069]

recently relocate gas water heater tank. all was fine until recently
tank is 2 yrs old, and has worked without issue for those 2 years until now
its an A. O. Smith 50 gal capacity
t/p valve opens and discharges about the same amount of water (1-1.5L)
but it appears only when the bathtub is used.
system regulator set @50psi,
temperature setting @ warm
piping system is 1/2pex
replaced the t/p valve issue persisted
had a repairman in , he claimed t/p valve defective, replaced with new issue persists
any help would be appreciated

 

[Twowaxhack]

You’re probably experiencing thermal expansion.

Google and read about it. There are several ways to control it.

Google “ how to control a water heaters thermal expansion “