2012 Discovery water heater

[railrider1]

We have a 2012 Discovery 40E The mixing valve on the back of the water heater has been replaced twice now due to lack of hot water at times and is starting to act up again. Anyone else having this problem? Does anyone have a good solution? I am thinking of just removing it and living with 6 gallons of hot water instead of the phantom "10 gallons ". It is just a pain to pull the water heater out to replace the mixing valve even worse to jump in the shower and not have hot water.

[Tha_Rooster]

I removed mine and took out the glue in the screw holding knob on as to remove the knob then ground out the safety feature so it can be adjustable. Then cleaned out the crude reinstalled no problems since no more cold showers. You shouldn't have to remove it to access the back.

[Old-Biscuit]

First off......

Factory set to maintain 130*F OUT of mixing valve
As mentioned that setting is 'tamper proofed' by sealing due to the water heater t-stat setting of 160*F

Mixing valves get clogged with scale/crud from hard water and/or lack of flushing/rinsing WH tank. It clogs up on tank out/mixing valve inlet so only cold water flows resulting in warm or cold water from hot side.

Removing mixing valve.........
Well the t-stat used to control temp heat cycle is 160*F
You can change that t-stat out for a 'normal' Atwood t-sat (140*F) ---fits in same place as XT Model t-stat----but you will also have to replace the terminal on Brown wire at t-stat with a 'small blade' female spade (XT Model uses a 'round pin')

So remove and clean/reuse------CLR soak etc
Remove and modify cold/hot plumbing lines PLUS t-stat
Or remove and replace with one from Big Box Stores...plumbing. 1/2" thermostatic valve cheaper then OEM mixing valve)

[mchero]

If you pull that mixing valve you will need to replace the T stat switch lower temp switch like old-biscuit suggested. May as well replace the ECO switch as well because they are both under that stickey pad.

Those EXT hot water heaters gets that water hotter than a chernobyl reactor core! Easily run the risk of scalding.

We FT in our rig and we don't have to winterize. Our EXT gets exercised. When it was acting up I would remove the cap and screw the mixing valve out & in a couple times then reset with DW at the sink with a digital thermometer.

[Cat]

How often you have to remove and clean and or replace the mixing valve depends on the mineral content of your water. In Tucson (very high mineral content in water) full timing had had to pull my mixing valve out every 4 to 6months and clean the deposits out of the check ball seat and reinstall. Atwood says because the cold water mixing with cold causes the minerals to solidify. After two years had to replace the mixing valve. So yes it is common.

[railrider1]

Thanks for all the comments. Ended up draining and flushing out the water heater then pulled the water heater out (yes you do need to pull the water heater out from outside on a 40E model) pulled and cleaned the mixing valve. Put it all back together and all is well again for now. Not a fun job in a campground but it is possible.

[mchero]

Good Job! Thanks for the update.