3 port valve trouble? - Plumbing Forum | Plumbers Forums

AJL Plumbing · 13-10-2008

Hi all, first post so please bare with me!
Working at a house on saturday, removed 3 rads, filled and bled system (open vent system,pumped with a y plan 3port valve ) turned hotwater on, worked fine, but couldnt get the boiler to fire or the pump when i called for central heating?
Tested the 3 port, (siemens) with the programmer on c/h only the room stat to max, the orange wire was dead, the white wire live, can anyone confirm my suspect of a faulty 3 port that needs replacing?
Thanks in advance
Andrew

dam · 22-10-2008

Replace the motor

sonray ltd · 22-10-2008

not always a motor. a motor can still be winding across and making contact with micro switch, but micro swtch faulty or the board.

you'll need to check for power at the motor and see is motor is working on heating call.

dam · 22-10-2008

should be a lever on the bottom of the valve.
switch the heating on pull the lever to manually turn on the heating. if the heating comes on surely this means the motors faulty

sonray ltd · 22-10-2008

as you say move the lever to man and boiler should kick in if not then yes i would look at the motor.
trouble is op has not given enough info for an exact fault to be given.
could also be seized spindle in hw only.

ajepo · 22-10-2008

If you say the orange wire is dead ,that is the wire which operates with the pump and boiler. it shouldnt be dead, sounds like you have an electrical fault.. Did you say when the stat is turned on full it still dosent fire up the boiler?

You can get a second opinion, but every veiw counts..

AJL Plumbing · 24-10-2008

Thanks for the replys, it seems that it may be stuck in hot water port, as the lever when moved dosent engage with anything,the stat was up to full and controller on c/h only but nothing happened.I think this must be the valve and moter at fault, failing that the signal from the controller?!

sonray ltd · 24-10-2008

it won't be stuck in hot water port if your getting hot water more likely to be in mid position.
if the lever has no resistance on it its in mid position.
if you have live on the white its not the controller.

sounds like its seized in mid position but not making contact with the microswitch.

change the brass valve or a complete unit.

AJL Plumbing · 25-10-2008

Thanks sonray, il change it and see what happens!

grahamep · 25-10-2008

Some misinformation here I think. These three port valve in their 'rest' position allow a path to the HWC but not the central heating. If it were stuck in mid-position then there would be heating as well. Sometimes the valve sticks and stops the motor. If the motor is demountable then I would suggest you demount it and then try. If the boiler fires in heating only mode then the valve is sticking, though it may well have damaged the motor. If the boiler doesn't fire then check the valve part manually for free movement and if OK just replace the motor.