NORITZ N069M TANKLESS Natural GAS WATER HEATER
We installed a NORITZ IN March of 2007. We have had water temp fluctuation ever since. We have had several opinions on cause of problem to no satisfaction. First we reran 3/4 line direct to gas supply about 5'. Second we contacted PGE and they resized the meter upward to 630 btu which is almost twice the size needed. I contacted NORITZ and went through the test procedure and all results were well withing operating ranges for supply and demand of water including outlet temperature. The flow through the heater during shower use was registering 1.5 gpm so have plenty of capacity. The temperature rise is from 58 to 120 degrees. A 60 degree spread and the heater should provide 5.5 gpm at that level.
The water pressure at the residence shutoff is about 60 to 70 during the day and does fluctuate a little within that range. At night the pressure has registered as much as 80 to 85 on the "WATTS'" Regulator Test Guage.
The NORITZ people felt that the problem was likely in our plumbing --like the MIXET valve in the shower. If the shower is in use the temp fluctuates slightly. If water is used any other location a dramatic change occurs. Not very pleasant.
I was about ready to remove the NORITZ and install a storage water heater to resolve the problem. Seems like a step backward so am looking for ideas.
The MIXET shower valve is a mechanical setting so don't see how that could be changing hot water flow. The only thing that I see is the input pressure change but no one seems to click on that.