Re-build watts mixing valve in Aquahot in place

[153stars]

It seems mixing valve has gone bad. It's like stuffed into to bottom even pressed in insulation somewhat. Looks like just buy the whole valve and replace the all but body "hopefully". I was able to turn it all the way up. The nut had come loose and knob just spun but I believe I have stem operating. It appears the Watts valve hasn't changed in all these years. I doubt I can get it loose without removing burner motor.
Any pointers?
Or should I use winterize valve and put a couple gallons through it. It would start cleaning cold mix side nearly immediately. There only a couple feet of pipe at best? Is the cartridge vapor filled? Who votes stuck and cleaning will free it up versus ,it's dead from age . It was first time I was really using the hot water for the year the AH seems to be getting up to temp.
Attachment 329183

[153stars]

Vinegar would of been a waste it was not that dirty. The plastic knob was stripped out and stem pretty stuck. I decided to run the nut on tight and use it to operate the valve after freeing up the stem/threads. Good old round wire brush in the body to clean it up. Had to partially remove burner assembly and get out of the way. Cleaned the electrodes and nozzle with brake cleaner while in there. The entire unit was rebuilt probably 100hrs of burn time ago by PO.
Hot went from 95 to 122f before assembling and re-lighting burner using water and loosing heat .I think 122f as high as my AC pen probe goes pegged. I can't be sure of actual thermostatic control at the moment. I will have to get another thermometer my turkey fry one seems to read a little low compared to AC . Its not 170f that's for sure I'm heating now . It's uncomfortably hot to hands but not terrible. Final heat I can stand hand in full hot flow about 3seconds, The wife could probably swim in it lol.
I say if you buy rebuild get the full valve and use full cartridge, little difference in price Home depot has best parts $17 but out of stock most places $30 could have been close out. Amazon has valve for $50 shipped. Reading reviews they say newer internals look a little different but work the same. One strange thing as I was fiddling with AH power ect the LP alarm started beeping twice. Its the 9v solenoid shut off LP type and past due for change. The sensors are available . My soldering skills are strong . I didn't see any any interconnection to AH in diagrams .
I did test the AH bay heater jumping the gas bulb thermostat I think thermostat id dead..
I finally spotted the the fan HX unit it works lol.
I'll add new valve for annual service next year.


.