unagi
New Member
I hope someone can help with real advice. Tech support at Navien just wants me to call my plumber so he can call them. For the last 3 years, the shower has been hot, then cold then hot again. It happens after about 10 minutes into the shower. Navien says it's the mixing valve in the shower or somewhere in the house that's making this happen. I can't replace every one, but have some and this does not fix it. In the last 2 weeks, I have had cold water to start, sometimes the e003 error. After a power shutdown and wait 5 minutes, it's fine, still get the hot and cold things happening. Its a combi, NG and we have 4 zones of baseboard hot water heat. The run is not that far from the boiler and the house is only 1600 sq. ft. Any ideas? Pressure valve? Control board?