What Causes Watts 70A Mixing Valve to Fail After One Year?

pine grove coal user · Post by **pine grove coal user** » Sat. Oct. 17, 2015 11:01 pm

What causes a Watts to fail after just one year? Are these units prone to premature failure? Or did I just get a lemon?
Depending on responses I'm going to get a Honeywell AM-1 1070 Series Proportional Thermostatic Mixing Valve. Unless someone can recommend a better unit.
The water in my Tarm is running at 190 degrees, and I want to have the domestic water around 120 or 130.

Post by **Rob R.** » Sat. Oct. 17, 2015 11:05 pm

It is possible you got a bad mixing valve, but They usually fail from mineral deposits and/or sediment. If you have hard water, expect similar results from the next mixing valve.

Scottscoaled · Post by **Scottscoaled** » Sun. Oct. 18, 2015 6:16 am

Isolate the installed one and screw it apart to see if it is jammed or loaded with mineral deposits

McGiever · Post by **McGiever** » Sun. Oct. 18, 2015 7:00 am

High mineral water plus 190* water is a bad combo.
Basically the thermostatic mixing valves all operate the same...if the water has high minerals or sediment you need to fix the water as the same issues will be had with any brand mixing valve. Many other benefits all around come with improved water quality.

lsayre · Post by **lsayre** » Sun. Oct. 18, 2015 7:10 am

Did it fail "hot" or "cold"?

I've had pretty good luck with a Taco 5003 mixing valve. Into its 5th year now and still working properly. I believe these may be drop in replacements for yours (but in the famous words of Ronald Reagan "Trust but verify!")