suburban SW4P water heater ignition troubleshooting

[RHarries]

I have a 2009 HAWK with a Suburban hot water system (Model SW4P), which has been acting erratically over the past few months. (Cold shower last night (BRRRR!).

Summarily:

1. The pilot ignition happens properly with the valve depressed in "pilot mode".
2. After holding the pilot ignition down for 15-30 seconds, I release the depressed pilot valve and I sometimes hear an audible "click" in the control valve.
3. Sometimes the HWH fires up and heats the tank. Sometimes the heat cycle is abbreviated without full temperature realization. Sometimes there is a failed ignition attempt.

In reviewing online info, it seems that perhaps I need to replace the thermocouple and/or the gas valve ($16 and $180 respectively). I "think" I tested the thermocouple properly, and found ~10.7 Mv across the thermocouple during the test. but I am not certain I executed the test properly (see image)

I am looking for advice on next steps, and also for guidance on to replace one or both of these mechanisms if that is warranted.

Thanks for all the advice this forum has provided in my educational quest!

Rob H.

 

[FAW3]

My first guess is the thermocouple. Remove and check for any deposits on the probe. While there, clean anything that you can get to like the gas tube. Reinstall and test, if no joy replace thermocouple with new. Retest and let us know.

 

[RHarries]

replaced the thermocouple and seems to be working fine. The thermocouple line (copper) was VERY difficult to remove and required cutting the line to remove with vice grips. BUT was a pretty easy fix..