Honeywell Motorised Valve H/W

[Drak]

Hi I desperately need please.

I have a problem with the HW on our S plan. When the programmer calls for HW the boiler doesnt fire up. The boiler fires up fine when calling for heat.
I have checked and theres power going to the motor valve and thermostat around cylinder.

I'm assuming the likely cause lays with the programmer, thermostat on cylinder or motor valve? Is there a way I can find out which is causing the problem before going out and buying a new part/ product.

Last night I swapped the wires over from CW and HW at the programmer, my aim was to test the HW motor valve. On the HW motor valve the lever had resistance when moving over to manual, does this mean the HW motor valve is working since I assume that the resistance is caused by water going through.

I'm not a plumber so my assumptions could be incorrect.

 

[DP]

Motor is goosed in HW diverter would be my initial thought.

 

[Drak]

Thanks. If the motor was knackered would the boiler still fire up?

 

[corgiman]

Thanks. If the motor was knackered would the boiler still fire up?

well the motor in the heating valve is ok isnt it, as you get heating?

so the motor in the hw one is knackered hence why you dont have hot water

 

[Drak]

The CH is working fine. Can the motor be replaced easily without the need to drain the system? The motor valve is Honeywell, is it a case of removing the silver box or would I better off replacing the whole unit ie valve and motor.

 

[corgiman]

its fairly straight forward job if you know what your are doing

IMHO you should contract a decent and recommend person to do it for you

 

[D_Hailsham]

I have checked and theres power going to the motor valve and thermostat around cylinder.

Does that mean there is a voltage on the valve brown wire when the cylinder thermostat is turned up?

Last night I swapped the wires over from CW and HW at the programmer, my aim was to test the HW motor valve.

All that would test is the programmer. Presumably you got the same result - No HW when the programmer was set to CH ON and CH working when programmer set to HW ON.

On the HW motor valve the lever had resistance when moving over to manual, does this mean the HW motor valve is working since I assume that the resistance is caused by water going through.

The resistance is caused by a spring which closes the valve when voltage is removed from the valve motor.

When HW is called (HW ON and stat set to high), the valve should open and you should not feel any resistance on the lever. If you are still getting resistance the cause is either a duff motor (£20) or a sticking valve. You can normally heat the motor running/stopping when the thermostat is turned up/down. If the cover has a small bump (about 5mm across) at one end, you can remove the actuator and check if the spindle is sticking.

Remove cover (one screw at the end of cover), undo two screws in diagonally opposite corners, lift of actuator. This will expose the valve shaft. It should turn easily by hand - about 20 degrees. If it is stiff, try lubricating the shaft with a little WD40 or silicon lubricant. If you can't free it, you will have to replace the complete valve.

If not sticking, visually check that the motor turns when the HW is turned on. If not, you will have to replace the motor.

If spindle and motor are OK, the only thing left is the microswitch in the valve. Replace actuator then turn HW ON and check there is voltage on both the valve grey and orange wires. If there is voltage on only one, the microswitch is faulty. This will mean a new actuator.

 

[Drak]

Thanks Chaps, all makes sense. Later today I will have the opportunity to carry out these checks, from reading your appreciated words, it looks like its in the valve/ motor area.

 

[Drak]

I have found the problem. The lever inside the head is not quite touching the switch, any ideas how to repair or just buy a new head?

 

[D_Hailsham]

I have found the problem. The lever inside the head is not quite touching the switch, any ideas how to repair or just buy a new head?

Have you checked that is not caused by the valve being stiff? Check the spindle can turn easily.

If the valve cover has a small bump about 5mm across on the top, you can buy replacement actuators and change without draining down.

 

[Drak]

Thanks, the valve moves with ease like you said 20 degrees. I have been quoted £41 for a new head v4043, so will give that a try.