Motorised Valve Is it working?

[cjb2611]

Hi, I have a problem with my central heating and hopefully someone can point me in the right direction. I have a fully pumped system controlled by a Potterton Suprima 60 boiler and a honeywell V4073A motorised valve.

Over the last few days I have noticed that when someone has a shower or bath the radiators loose all their heat. When I feel the pipework from port A of the valve it's cold and stays like that for ages, the boiler doesn't seem to fire up to recify this.

When the system comes back on in the morning the radiators and hot water both warm up nicely it just seems to be when the tank is emptied that the problem arrises. Was wondering if the cause was the motorised valve but would like any advice before replacing it. Any help would be greatly appreciated.

Best Regards
Chris.

 

[Mbear]

Without voltage diagnosis on the wiring/valve then it's difficult to say.

You'll prob need someone in to check, it may not be the valve, for eg it could actually be your hw cyl stat

 

[dontknowitall]

Probably.

The pipe going up to the motorised valve will be hot from the boiler. When the hot water is calling for heat the pipe to the cylinder will warm up. When the heating is calling for heat the pipe to the heating circuit will warm up.

When the motorised valve is working the lever is floppy and when the heating and hot water are turned off the lever is stiff to move. (I think it goes to about halfway for heating and fully across for hot water.)

If you keep the heating off and turn on the hot water to call for warmth then move the lever across to the right this should warm the hot water up. If this happens then you need to change the motor inside the motorised valve or the actuator head.

 

[PlumbBobBob]

what is the cyl stat set at?

 

[cjb2611]

what is the cyl stat set at?

It's set to roughly 57/58 degrees

 

[cjb2611]

Just got home from work and although heating had come on at 4pm the rads were barely warm. I switched the boiler off and pulled the manual lever down to the man/open position and it just stayed there, thought it should have returned to at least half way. Returned the manual lever to the mid point position manually and put the boiler back on and it fired up and stayed on until the rads were up to temperature to the TRV setting. As you say this points to a problem with the motorised valve but is there any way of checking if I only need to replace the motor or the whole Powerhead.

Best Regards
Chris

 

[jtsplumbing]

Depending how easey it is to get at change the sycron motor first (cheep part) if you have the valve that the head comes off , its ease`r to change the motor, got a fiddley little screw that holds it in place, also if head is off check how easey the valve moves, as it may be the body that is faulty and not turning.

 

[AlexP]

Here is a link to how the valve works.
Central heating - Answers - Central heating Mid position motorized valve

once you know how it works, its easy to diagnose and repair.