water temp changing with pressure

[rlipford]

As I am taking a shower, the water temp is changing in relation to the water pressure. As the pressure reaches cut out pressure at the tank the temp is hotter, and cools as the pressure drops to the start pressure. I have a new water heater and the pressure switch is set at 35-65 psi and is working correctly. Any ideas how to stop this? The temp difference is about 10-15 degrees from high to low. Thanks for any ideas.

[PLUMBER RICK]

without getting into real deep details, a pressure balance or temperature type valve will maintain the pressure between the hot and cold. the temperature type valve is more costly and is also more delicate.

rick.

[westcoastplumber]

Sounds like a Anti Scald Shower valve and the cartridge is bad.

Can you either give us the model and type of shower valve you have, or take a picture of it?? Do you know if you have a pressure balance shower valve??


This pressure problem is only in one shower correct?

[DuckButter]

I think what both posts above are referring to is a pressure balancing shower valve.
When your pressure is higher the hot water is surging with better flow than the cold, as it drops the hot flow dies off.
We could go on for hours with every possible theory of how the water lines may have different levels of resistance.
Bottom line is this is a problem a functioning pressure balancing cartridge on your shower would solve.