Water pump always on - plan of action

[flyby2013]

Hi all,
since a few days my water pump decided to be always on: I was using the kitchen tap (hot water) and the pump didn't switch off after I turned the tap off.

After some investigation I have isolated the problem to the flow sensor on the hot water outlet and disconnected it; now the pump turns on only if I switch the cold water on (it also pumps hot water in that case, it just doesn't turn on if I switch *only* the hot water on).

It seems to me that it's either of the two:
(1) flow sensor is faulty;
(2) there is a leak on the hot water pipes.

Unfortunately I have no shut off valves on the outlets so I cannot switch them off to discard the leak hypothesis. I have also noticed that there is a non-return valve installed on the hot water inlet and from what I have read it should not be there because it could damage the pump.

My plan of action is the following:
(1) add two ball valves to the outlet so that I can switch the outlet off and rule out the leak theory;
(2) remove the pump and visually inspect the flow control sensor within the pipe (not sure if I'll be able to see whether it's stuck);
(3) remove the non-return valve on the hot water inlet.

Does this sound OK to you? Any other suggestion?
Unfortunately the pump maker (Damixa) is not making water pumps anymore and it's impossible to find parts so if the culprit is the sensor I should find a way to fix it..

Thanks in advance!

 

[Killy Bing]

If it was installed and registered between 2007 and 2010 then bristan group will still support it.

 

[flyby2013]

What about removing the non-return valve on the inlet and adding the two ball valves on the outlet? shouldn't I do that in any case?

 

[Killy Bing]

It would have to be a fair leak to cause the pjmp to fire. You could put the sensor back on, turn it back on, mark the level of water of your cold tank and isolate it and see if it empties at all.

however from experiance it will be the sensor knackerd. Time for a Stuart turner pump!!

 

[Killy Bing]

Oh also please note that if their isn't a leak and the pump continues to fire it will kill it anyway from the build up of heat

 

[flyby2013]

It would have to be a fair leak to cause the pjmp to fire. You could put the sensor back on, turn it back on, mark the level of water of your cold tank and isolate it and see if it empties at all.

however from experiance it will be the sensor knackerd. Time for a Stuart turner pump!!

Unfortunately this happens only for the hot water outlet and I cannot access the hot water cylinder (it's below the cold water one). I'll try to isolate the outlets and see if it fires. Thanks!

 

[Killy Bing]

Your cold storage tank feeds your hot water cylinder, if you isolate the ball valve feeding it then you can observe that tank