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Error code 52 on a r63lse tankless water heater. Hot water service becomes intermittant water gets hot then cools may or may not restart without turning flow off and then back on. How do you check the Modulating Solenoid Valve? Thank

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Just a first thought on this one. I had a fault on a new unit where dust had got in to the gas supply and completly stuffed up the modulating adjustment. Took me an hour to figure it out and about 3 hours to strip the gas valve down and clear it out. Problem is the Rinnai has a large micron steel gauze on the gas line filter in the bottom of the gas valve and lets small debris through. If you have had any work done on your gas line recently just keep this one in the back of your mind.

The modulating solenoid is the large one on the front of the gas valve, next to the circuit board, the pin connecting it can go either way around.
If you are good with electrics you can check the resistance across the solenoid. UNPLUG THE POWER SUPPLY BEFORE OPENING THE FRONT CASE. Take the white lead plug off the solenoid and put a ohms reading acroos the two terminals. Hopfully you should have a little plastic sleeve attached to the inside of the front panel with a single A4 data sheet. On one side of this should be a list of the test points and what reading to expect. Check this if you have it but as a guide 60-100 ohms is what you are looking for.

As far as what might be wrong my hunch would be either PCB or the valve itself, Rinnai solenoid valves are normally really good so I would go with a PCB if I needed to try something. Dont try adjusting or replacing the gas valve unless you digital gas pressure testing equipment as the settings are crucial to the safe operation of the heater.

Posted on Aug 03, 2010


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