Detecting ice in water pipes....by using a motor?

[eem2am]

alexan_e..

that is good thinking....

you have got me thinking now,

maybe we could put a solenoid valve at the mixed outlet...

..this would also be good if it was a normally closed solenoid, because this would take care of our second bugbear, which is the problem of wasting water when the mains fails whilst the stepper valves are open.

 

[srhoar]

Here is how to look at the problem. Pretend the ice blockage is a vale upstream in the system. The task is now to detect the state of that upstream valve. So, here is what you do.
1) Place a pressure sensor up stream of your cold water servo.
2) Now, take a reading on the pressure sensor. If zero, then there is no cold water at all.
3) Slightly open (just a bit) then shut the cold water valve. Make this operation fast and very short. You are not opening it, just cracking it off its seat.
4) Take another reading of the pressure sensor.
5) Compare the difference. If it drops a lot, then the cold water is blocked. Inhibit the Hot water servo.
6) If the difference is small, then cold water is available, enable the Hot water servo.

We had this same problem come up on some Nuclear Reactors I worked on.

Red