Atwood Mixing Valve

[sheriff1]

Once you get the body off the brass part removes easily with a socket, 1 1/16” as I remember.

[sb55]

I just remove and rinse the screen on mine. Why replace the whole thing?

[sheriff1]

Originally Posted by sb55

I just remove and rinse the screen on mine. Why replace the whole thing?

Same here.

[Too tall]

Wolfraat that's great work. Good pics. and a nice clear detail.

[wulfraat]

Originally Posted by sb55

I just remove and rinse the screen on mine. Why replace the whole thing?

I wasn’t sure what I was dealing with regarding how the valve was failing... so I just ordered another one planning on worst case... so I could go camping this weekend with hot water [emoji4]

Now I have a spare assuming the old valve issues were limited to junk in the valve....

[Bgibbs]

Thanks for the great pictures. I wish my water heater was as easy to get to as yours. Mine is under the street side twin bed and I can barely see the mixing valve without removing the bed. Again, thanks. So much to learn!

[Too tall]

Wufman. Thanks for the wrench size reminder.
We have a new trailer, well it is 1/2 season old. De-winterized today and classic mixing valve symptoms which I'm a expert on from experience with the prior trailer. No worries, checked the usual stuff like faucet screens etc. but I knew.
There was some gunk on the screen that I easily cleaned and a new, shoot me now, mixing valve arrives tomorrow.


My question, how do I test the old valve to determine if it is good? I'm able to blow air easily thru all sides of the valve EXCEPT cold water in. If that's how it is supposed to be it's good and the silly gunked screen was the problem and I'd be OK re-installing the bugger and shelving the new valve as a spare.


Because we like pictures. Below are pics. of the brass part which is the first to thread into the HW tank. This has the offending screen and a check valve facing out.


For the conspiracy theorists here the little hunks of garbage sitting on my well loved curly maple cutting board are hunks of plumbers putty. Bonus prize if you guessed this made it to the kitchen sink faucet. Ouch. I'm imagining that these critters might be inside the valve???

[Too tall]

Nobody is going to take a swing at how to test?
I'll call the mfg. Wish me luck.

[rmkrum]

Note that the cold side of the valve should be shut if the outlet water temperature is below the set point. If the valve is cool enough to blow into it, the cold side being blocked is normal.

The only way I can conceive of testing it would be to connect a heatproof hose to the cold side, dunk the whole valve into hot water that is heated to at or above the set point and see if air will blow through the cold side once the valve warms up. Kind of a backwoods engineering approach, but a crude way to verify the valve opens and allows cold water flow as intended.

Personally, my OEM Atwood 6 gallon water heater did not have a mixing valve, and I pulled it out and went to a tankless one instead. (PrecisionTemp 500 series).

[Too tall]

Thanks RM. That is along the lines I was thinking. I might tinker with the valve adjustment to confirm.


FWIIW After dunking in hot vinegar the plastic protective cover over the phillips screw that holds the large black cover pops off with no effort.



*It's a hobby*

[Too tall]

That's done. All is well for now.


Mavens of the mixing valve render your take on how this is prevented forever. We take the usual precautions by rinsing the tank before startup and use a water filter (external to the trailer).



Remove the screen? Water softener?

[perryg114]

What is the purpose of that valve?


Perry

[rmkrum]

Personally, I’d just plan to carry a spare and do preventative maintenance on it every year.

Leaving the screen off exposes tiny critical seals and clearances to getting ‘stuff’ in them to screw up the valve.

Soaking the valve by itself in hot vinegar once a year might keep it cleaner.

[Too tall]

Understood RM, I'm fighting the notion of removing plywood and undoing the valve every year. It feels alot like not working smart.

[rmkrum]

Originally Posted by Too tall

Understood RM, I'm fighting the notion of removing plywood and undoing the valve every year. It feels alot like not working smart.

If you had one of those pump input bypass valve gizmos for putting antifreeze through the system, I could see putting that suction hose into conveniently placed bucket of vinegar solution and using the water pump for pumping it through the system whilst dumping the hot water output from a sink right back into the same bucket. Or just plug the sink and use it as the supply tank. It would be a closed loop. (Disconnect shore water).

I’m having an minor issue with my my tankless and that’s how I plan to try to get the probable calcium deposits out of it.

That would remove calcium or lime deposits but not plumbers putty...

[Too tall]

Clever RM, clever. I can see doing a bi-yearly PM of the tank using the suction side of the water pump to fill a drained tank. Than heat it, leave to marinate for a bit than drain/rinse <<< I stole that idea. That's "tolerable"


Simple, sensible and not so bad as they say in Minnesota.

[rmkrum]

Originally Posted by Too tall

Clever RM, clever. I can see doing a bi-yearly PM of the tank using the suction side of the water pump to fill a drained tank. Than heat it, leave to marinate for a bit than drain/rinse <<< I stole that idea. That's "tolerable"


Simple, sensible and not so bad as they say in Minnesota.

I was considering just circulating the solution (enough to fill the water heater tank) more or less continuously while the water heater slowly warms it up. That implies the suction hose can take the heat.

Side note:

The phrase, “It’s not so bad” was one of my earliest memories of my very Norwegian grandmother on my father’s side. The other phrase was “Uffdah” when things really went south.

Grandma and Grandpa emigrated to Canada in the 30s as far as i know. Dad was born in Toronto, Canada and they eventually emigrated to Chicago, Illinois area as a little kid.

I grew up in that culture, and usually split a gut laughing at Garrison Keeler’s ‘Prairie Home Companion’ show that seemed to be a documentary of my growing up time with dad’s parents. I can sort of follow written Norwegian.

My mom’s side of the family is German and Viennese which is where I learned to cuss my tough engineering issues in slang German. Although Cantonese is a much better language for that. My DW, the “Dragon Lady”, has also taught me a lot of colorful language ... It’s funny how you pick up the cussing part of the vocabulary first, then you learn how to count money!

[Daquenzer]

Originally Posted by perryg114

What is the purpose of that valve?


Perry

The purpose is to mix the cold and hot water in the correct mixture so that you don’t get scalded when you use the water. There is a sensor on the valve that will adjust the mix. If that sensor get crud on it the valve will not work properly and you will get a cold shower.

I only had my AS a year and had a problem. A lot of it has to do with water quality at some of these campgrounds. I bought a better quality water filter and I now use a water softener to keep sediment out of the water.

You can clean the valve by soaking it in white vinegar. It worked for me. I did buy a new one and installed it. But I have the old one just in case.

[JJTX]

Mine is coming out of the shop soon for this replaced under warranty. Hopefully they noted somewhere what it looked like.

I have a new double filter setup and a water softener to fix this problem. I'm pretty surprised this 'valve' didnt last two years with weekend use. Though, I think it was due to a water line failure at a state park when we were there, that clogged it.

Hopefully my double filter setup will stop this from happening again.

[rmkrum]

The basic problem is that bits of scale or sediment can jam the valve slightly open and mix too much cold water into the flow of hot water.

I’m glad my tankless does not have one. Admittedly all by itself it is probably more sensitive to scale and grit in the gears than the Atwood mixing valve.