Intermittent CH pump operation. HW OK

[Richardah]

It's stopped working again - no surprises there. But voltage readings are different

Voltages on leads to motorised valve:

White 240 !
Blue 0
Grey 240
Orange 0

Thanks in advance for any comments

Richard

 

[Richardah]

I should have mentioned that the thermostat black and white wires both have 240 V

Richard

 

[Agile]

It seems that the valve is motoring but not activating the microswitch.

If thats the case and you have fitted a new head then the obvious guess is that the valve is not moving quite as far when activated as the head expects.

The rubber ball inside the valve is meant to rotate on its shaft so that it always presents a different sealing face.. Sometimes these become stuck and the constant sealing in the same position deforms the rubber and causes the sealing position to be slightly different.

In all probability it would be possible to bend the switch actuating part of the head slightly to ensure that it does become activated.

Tony

 

[Richardah]

Thanks for coming back to me so quickly, Tony

The microswitch nearest the motor is on. Applying more pressure to this does nothing.

However, if I press the other microswitch (I presume the boiler), the pump starts running, with the water diverted to the radiators.

I'm leaving a screwdriver pushed in there to warm up the house

Richard

 

[Richardah]

I am posting this for the benefit of anyone else finding themselves in this situation, and particularly to thank all those who took the time to give me their good advice.

I'm particularly singling out Agile (aka Tony) who was spot on with both problems.

To cut a (very) long story short, I now feel confident in revealing the following:

1 The main problem was the 3 way valve, which intermittently opened only partway (presumably because of the distortion described by Tony). Once this was replaced, the failures became much less frequent, and were due to:

2 An intermittent fault with the thermostat receiver (presumably caused by the relay, as also described by Tony). I have put in a temporary fix by bridging out the thermostat, and the whole system has been behaving for long enough for me to believe that both problems are fixed. Of course, I still need to replace the thermostat, but I'll wait until the weather is warmer before taking the system out of action.

Again, thanks to everyone for all your help.

Richard