Delta shower faucet either too hot or too cold

[Sterlingrepairs]

After a plumber installed a Delta Multichoice valve with a single function cartridge, the shower gets hot water only if turned to max which is too hot. But if the handle is turned down just a little, the water is too cold. The plumber is blaming it on the water heater, but the other shower in the house works just fine. He replaced the cartridge with a new one and still the same problem. How can this be fixed?

 

[Jeff Handy]

Contact Delta customer service for technical support.

Maybe there is a problem with the pressure balancing unit.

Does the new valve have service stops, if so are they both fully open?

 

[breplum]

Unusual symptoms, for sure. Do what Jeff H says and let us know.

 

[Sterlingrepairs]

Thanks, I contacted Delta still waiting for response, but good suggestion to check service stops. Thanks!