Dodgy Motorised valve?

[Redhotferrari]

Hi Guys,

having recently changed a cylinder thermostat that was not working, I think the problem may have been the motorised valve.

Symptons are:

With just the controller on hot water the stat on the cylinder fires the boiler when turned up and turns of when turned down, I think there could be something wrong with the divertor valve (Honeywell 549814 is stamped on the case) With the central heating and hot water on, i have turned the stat on the cylinder down so not heating the water at all, but with the room stat up to 25 the boiler does not fire (house is colder than that as I can hear the stat click on about 18) if I go to the valve the arm has moved over to the right, but not fully, if I push the arm to the right fully the boiler comes on and radiators start to work.

The problem is that to test it I turned the wall stat down and the boiler shuts of as you would expect, but turning it back on does not fire the boiler again, until I go through the process again!

Is the valve faulty? Can I just replace the top motorised bit or does it have to be the whole valve? Could do without having to drain the whole damn system if I can, there are no isolation valves etc either side of the valve.

Please help...............

 

[ollski]

Probably just a new synchron motor inside the valve head required.

 

[Redhotferrari]

Thanks, Cant really understand how the valve not working correctly would stop the boiler firing though?

Thought it would just fire from the room stat but not divert to the heating correctly

 

[gasmick2]

HI as the other post says just relace the motor its only 2 small screws and the electrical connections but beware turn OFF the boiler at the mains as ther is a permanent live in the valve
as you say the boiler will not fire thats because its not motored over to close the switch that supplies the mains to the pump and boiler
just for now there is a lever on the side pull it as far as you can you will hear a winding noise thats the motor then just clip it int a slot provided for the manual position then your heating will work even when its on water only till you replce the motor#


mick

 

[Redhotferrari]

Thanks for all your advice on this guys...

I assume this is a completely 'dry' job, and just need to ensure electrics are off?

Have found a replacement motor made by Honeywell, do these fit any of the Honeywell valves?

Cheers

 

[Redhotferrari]

Anymore thoughts on this?

have done a bit more research on the forum, and to add a little to my original post, when I push the actuator? arm, I can hear the motor turn so does this indicate its OK?

The thing I cant get my head round is that with the CH and HW on, the room stat does not fire the boiler, looking at the arm it is near enough right over to the MAN (rigth) side but I can only get the boiler to fire when I push it right over to the MAN side, it moves about 3-5mm when I do this this...

Sorry to ask again but would love some clarity with this if possible?

Dont want to change the motor etc if its something to do with th new wiring on the cylinder stat.

Many thanks guys.........

 

[ollski]

you get heating when the water is on as the motor pushes the valve open as much as it can which is enough to open it but not to switch the heating microswitches on, but as your hw is calling for the boiler the heated water can now flow through the valve both ways.
It is the synchron motor, but it may be failing due to a siezing valve...try it, for 12 quid or so it won't hurt.

 

[Redhotferrari]

Thanks olski,

Could this also be why the hot water is getting very hot? It seems hotter than the stat is set at.....could it be that the valve is not closer and the water is still going through the coil in the cylinder?

 

[ollski]

That's probably because your stat is more accurate than the previuos one...unless you have latched the valve open in which case the hw will get to the temperature set on the boiler thermostat.