3 port valve synchronous motor

[alhay]

I have just fitted a new sync motor to my 3 port drayton mid pos valve. With the central heating calling for heat and the hot water calling for heat, i.e. a cold system, should the internal micro switch be clicking constantly holding the valve midway until either hot water or heating is satisfied, then the valve completely switches one way or the other? I have not noticed this before.

 

[Registered Gas Man]

A three port valve allows HTG and HW to be heated at the same time.

To achieve this the valve holds itself open in the mid position.

So yes, that part is normal. But the constant clicking??

 

[alhay]

Yes the micro switch clicks approx 2 or 3 times a second fairly constantly and the sync motor is whirring at each click.

 

[corgiman]

Could be the micro switch is faulty and not shutting of the 240 to the gray wire

What make is it mate, if its a honeywell try a complete new actuator

 

[alhay]

Its a danfoss. The reason I changed it was, from cold startup the room stat made ok when temp reached but the heating kept running getting hotter. The port valve stayed on heating and the hw tank didnt get any hotter, never operating the tank stat. I changed the room stat, the tank stat and the port valve sync motor to no avail. The boiler is a Potterton Envoy 60, I think the control unit has failed as all the time the boiler has power the port valve opens to the heating position even though all stats are satisfied.

 

[ChrisR]

It shouldn't click in the middle all the time - DC produced with a diode should lock it. But if the diode pops then they hunt to and fro.

But if you're getting no CH at all it sounds like the valve is stuck shut ?

 

[alhay]

The heating is working fine. It just wont switch off even though the room stat is made. The port valve wont change over to the hot water position cosequently the heating stays on. The port valve is not jammed and can be easily moved with the valve head removed. If I switch the whole system power off , turn the room stat down,to make sure heating is not called for, then re power, the port valve closes and the hw tank reaches temp ok. Then if I turn the room stat up the whole system functions ok. It is purely when the hw and heating are both calling for heat. I'm going to ring potterton tech help because I'm pretty sure it's a boiler control pcb that has failed. The system is 7 years old and worked fine up to now.