CH Problem - CH not turning on

[Rob_Quads]

I have a Boiler/Water Cylinder/Central heating setup.

Drayton LP522 Timeswitch/Programmer with Drayton RTS1 Room Thermostat

So far it does the following

Turn on Central heating....Nothing Happens
Turn the thermostat up/down and you can hear it clicking. Left it at 30 degrees i.e. def on

If I turn on the water heating with the CH still on then the boiler fires up to heat the water and the radiators also heat up.
Once the water is up to temp it obviously stops the boiler but as a result stops heating the radiators.

To me it looks like either the Thermostat is not working or Timeswitch is not working. The boiler obviously works when its told and the valves all appear to be working (once there is hot water to feed the system)

Think the next step is to undo the thermostat and 'short' the on connection which should either show up the thermostat as the problem or count it out.

Any other suggestions.

 

[seco services]

find the wiring centre probably in the airing cupboard and check them all there.
i would turn heating on, stat up, and water off and see if you have power on the white wire in the control box

 

[MANDATE]

Rob you've only mentioned a programmer and room stat. Is'nt there a motorised valve.
If you have a 3 port mid position valve, then it is moving to mid position, cause you get HW and CH. That proves the room stat is ok.
It is most likely not moving to the CH only position due to faulty motor or if it is moving to CH only position then boiler not lighting due to faulty microswitch.

 

[Rob_Quads]

Thanks for the comments - there is a control box in the airing cupboard so I will check voltages in there.

MANDATE -> Even if I had a faulty motor would you expect the boiler to have fired up when it was switched to Central Heating, of are there safety switches in it to make sure that it only works when the pump is working

 

[seco services]

if it moves to mid position the motors ok but could be a faulty microswitch

 

[MANDATE]

When its on HW only or HW with CH the cylinder stat provides the power to light boiler and run pump. If HW is off or satisfied then valve should move to CH only position. As the cylinder stat is not operating power has to come from elsewhere. So it comes from the orange wire of valve, but it relys on one of the two microswitches being triggered.
So the problem could be valve not moving to CH position (motor/stiff spindle) or if it does move to CH position then faulty microswitch.

 

[Rob_Quads]

Not got my multimeter to had at the mo so can't check the wires. Looks like a bit of a botch job the way they have all been crushed into a box.

Looking at the valve it looks like....

Hot water only on - Valve switched to "W"
Hot water & CH on - Valve switched to "M"
Hot water off & CH on - Valve stays switched"M"
Hot water & CH off - Valve stays switched"M"

 

[MANDATE]

The quadrant has to move over two halves. there are two power supplies, one for each half.
There is a strong spring and when power is removed, the quadrant/motor is wound back to the initial start position or arrested at the mid position as required.
When CH only has been selected, the room stat provides the first power supply to the 'white wire' of the valve. this drives motor to mid position.
The programmer provides the second power supply to the 'grey' wire of the valve. Both are connect to same microswitch, so at mid point the 'grey' takes over from the 'white'.
During the last half of movement a second microswitch used to provide power to a pcb, used for hold motor at mid point, is triggered and provides power output through the 'orange' wire.
From your description your quadrant/motor is not going beyond mid point which suggests the problem is motor/valve spindle related.

 

[Rob_Quads]

Hmm So it sounds like its probably the faulty Mid Position Valve.

Looking back I have now found a few others posting here with the same fault and same model of valve - ACL Lifestyle 679H340 30L0

..Just as I was about to post i thought - lets reset the power.

So I turn the heating on....tripped the power to the heating system....turned it back on again....and we have heating only!!

Looks like I will have to keep an eye on this one. Thanks for everyones comments