Combi boiler DHW too hot

Cah283

Hello! I have a UTICA CuB CCB 150 gas Combi boiler. For the past month the DHW has been extremely hot well above the 118*F the thermostat is set to. I replaced the control board, the DHW sensor, and the safety sensor but it is still very hot. Any ideas on what is causing it?

kcopp

Is there a mixing valve on the boiler for the hot water? one like this? https://www.caleffi.com/usa/en-us/catalogue/mixcaltm-adjustable-thermostatic-and-pressure-balanced-mixing-valve-npt-521400a

DZoro

You should have a anti scald / mixing valve installed in your domestic hot water line. That unit will and can vary temperatures between 104* and 140*.

Has the plate heat exchanger been cleaned annually?

Snowmelt

Who told you to replace the board. did you de-scale the heat exchancher?

hot_rod

Was it accurate when first installed and up until now? A new problem or condition?

jscivolette

These units should not have mixing control on them