The valves could be connected to a flooding sensor. 

We too run solenoids on our downstairs hot and cold water supplies as they are below the sewer line so waste has to be pumped, if the pump fails or throws an error the water instantly shuts off with the solenoids so we cannot flood out.

About a year ago we noticed very low hot water flow and it turned out to be the solenoid.   The plumber took a while to find the part and it eventually went from light clicking to making one hell of a racket (I think it was continuously trying to open and close).

Simply anecdotal but it might be that you have something similar going on.

@duckDecoy @bung 

Yes there is a downstairs sewer pit and pump. I suspect the solenoids are triggered to stop flooding if the sewer waste unit isn't triggered to empty the enclosed sewer pit unit. This occurred once as the sewer pit didn't empty and flooded back to the bathroom. The sewer pit float sensor to do that was stuck AND the overflow alarm didn't trigger either. Both fixed and retested.

@K1w1k1d I assume the issue could simply be the valve is struck partially open with grim, lime etc so and if so can be cleared?. That would seem more likely than the solenoid itself failing with the valve partially open?

FYI the unit is a NC (not closed) solenoid so its odd is partially closed?

FYI Zip quoted $225 for a same spec replacement then I'd need to get a plumber or fit myself

@concordnz you have a point in regards to simply not having a solenoid as it appears to be only managing a situation of the sewer pit not emptying AND water left running?

xlinknz:

 

FYI the unit is a NC (not closed) solenoid so its odd is partially closed?

 

NC should be Normally Closed needing power to open. So if power is off and pump not available the valve fails safe.

Hi all

I found I can get the same solenoid but from Canada

Mine is 240V 50Hz and 11VA the offered replacement is 230V  50Hz and 17VA

I am told that is compatible, can anyone confirm that especially the 11VA vs 17VA difference

Regards 

The replacement is slightly "gruntier" ie will draw aprox73mA while running... (might need to overcome a larger spring... or not) don't worry about the difference

By "solenoid" do you mean the complete valve assembly, or do you just mean the brown solenoid coil that slides over the cartridge shaft?

There may be a blockage somewhere else in the pipework so I would recommend the following tests to confirm that the valve is the problem.

Disconnect the valve inlet pipe to make sure you have full water flow to the valve?

Reconnect the valve inlet pipe and disconnect the valve outlet to make sure you have full flow through the valve when it is energised?

The coil is probably not the problem unless it has visible signs of being hot, eg bulging sides, discolouration, etc.