Is there a problem with the Grundfos Comfort Series Undersink Valve that causes it to lock in the open position?. One of my valves has done this causing the cold water faucett to run very hot. Ironically, it is on the side of the house that is used the least
Water Heaters - Grundfos - Comfort Series Replacement Valve
Answers & Comments
This is a common problem with this valve. Try placing the valve in near boiling water then set to cool before trying again. It worked for me until the next time it failed and I got a different system.