Water Temperature Constantly Fluctuating

[mikem 0]

Hi,

Our water heater does not hold a steady water temperature. When I shower the water temperature can fluctuate between almost scalding hot to quite cold without me touching anything. I'm guessing it's a problem with the water heater, because the same thing happens in both showers and the bathroom sink as well.

I have a Rinnai water heater, though I'm not sure which one exactly. It sits outside and has a digital control panel inside with the model number MC-45-SR. We set it to 40 degrees.

Is there anything I can do myself to try to fix the problem or diagnose it further? Or is my best bet to call Rinnai and have a technician come look at it? Or maybe someone can recommend a good technician?

Thank You!

[bepgof 20]

Hi,

Our water heater does not hold a steady water temperature. When I shower the water temperature can fluctuate between almost scalding hot to quite cold without me touching anything. I'm guessing it's a problem with the water heater, because the same thing happens in both showers and the bathroom sink as well.

I have a Rinnai water heater, though I'm not sure which one exactly. It sits outside and has a digital control panel inside with the model number MC-45-SR. We set it to 40 degrees.

Is there anything I can do myself to try to fix the problem or diagnose it further? Or is my best bet to call Rinnai and have a technician come look at it? Or maybe someone can recommend a good technician?

Thank You!

Look like the firing angle control to the Triac is loosen or malfunction. Switch off power, dismantle the cover, pull and shake the cables, check any loose connection. If not, can consider to get a new set.

Edited November 22, 2010 by bepgof

[Chiang218 0]

Is this a instant water heater?

Set the temperature lower and knock the flow switch. Most likely is that water flow switch is partially stuck so when it sense that the water is flowing, the heater will cut in, once it sense no water flow it will cut off.

Otherwise check your shower spray, see if the water pressure is good.