My Drayton LP722 is not operating properly. Help please :)

[Robhutton3]

I have a Drayton LP722 central heating controller. Recently the hot water timer is not firing up the boiler (Baxi Solo 15 HE A) consistently. I noticed on the Monday evening (7.30pm - 8pm) that the boiler hadn't been triggered to turn on even though the light was green on the timing controller. If however I put on the central heating it turned on.

What was most strange is I left the Hot Water on timed mode, Heating off, and it did turn it on the next morning (7am - 7.30am).

Coincidentally I had someone from Baxi out to repair some parts on the boiler after a service so spoke to them about it. He asked me to switch on the hot water and it wouldn't turn on. The only way to get the boiler to trigger was by switching on the heating timer.

We then noticed that with the heating is on by itself, but the thermostat turned down so the heating doesn't kick in, it switches on the boiler in Water mode on the Drayton Motor Valve. If I then increase the thermostat for that the heating to turn on it changes to Water & Heating. It never goes down to just the Heating setting.

I've tried changing the 1st programon the Hot Water timer to see if it will switch on again on the same day but it doesn't.

I'm now waiting until tomorrow morning to see if it once again switches.

Any thoughts?

 

[ianmcd]

It is most likely the motorised valve or room thermostst that are faulty it isnt the boiler, post pics of your controls when in CH mode pnly and the room thermostat turned fully up

 

[JohnD]

If I then increase the thermostat for that the heating to turn on it changes to Water & Heating. It never goes down to just the Heating setting.

Perhaps it is set to Gravity HW

 

[Robhutton3]

It is most likely the motorised valve or room thermostst that are faulty it isnt the boiler, post pics of your controls when in CH mode pnly and the room thermostat turned fully up

Thanks for the reply. Hopefully these images help. The image where CH mode is on only and thermostat turned up is the one where the Drayton valve is in the M position (also like that if HW is turned on as well as CH with thermostat up). If the thermostat isn't fully up but CH on then the boiler fires up, as does the valve, but in the W position.

If CH isn't on it doesn't fire up.

I'm intrigued to find out if it fires up tomorrow morning on just HW timer like it did today. That will be the real twist that I won't understand.

 

[CBW]

Perhaps it is set to Gravity HW

Doubt it would work intermittently on dhw alone.

 

[CBW]

@Robhutton3 - how comfortable are you with electrics and do you have any test equipment?

 

[Robhutton3]

Doubt it would work intermittently on dhw alone.

@Robhutton3 - how comfortable are you with electrics and do you have any test equipment?

@CBW - I agree but last night it was experiencing the same issues and then turned on this morning just on HW. I'll report back in the morning with what happens.

I'm probably more likely to short circuit the house/shock myself if I try and do something. I also don't have any test equipment but could likely get some from colleagues if it isn't too difficult as I'm sure I could work it out.

 

[ianmcd]

OK thanks for the pics, it is definately not the boiler, it is and external control fault,

 

[ianmcd]

Perhaps it is set to Gravity HW

If set to gavity, then when selecting CH only then the HW light on the programmer would also come on, as you can see this isnt the case

 

[JohnD]

...It never goes down to just the Heating setting....

?

 

[Johntheo5]

Looks like valve actuator fault.
Is the cylinder stat calling for HW each time HW is requested?, check/note its setting then turn it up/down to hear it clicking, return to original setting, normally 60C.
Request both HW&CH, valve should be in mid position, then turn cylinder stat down, check if valve goes fully over to CH only.

 

[ianmcd]

?

well he was mistaken #4

 

[Robhutton3]

@ianmcd @CBW
The HW only didn't trigger the boiler to turn on this morning so it does seem that there is a fault with that connection.

 

[Robhutton3]

Looks like valve actuator fault.
Is the cylinder stat calling for HW each time HW is requested?, check/note its setting then turn it up/down to hear it clicking, return to original setting, normally 60C.
Request both HW&CH, valve should be in mid position, then turn cylinder stat down, check if valve goes fully over to CH only.

@Johntheo5
I removed the stat from the cylinder and left it around 60° and it wouldn't fire up.

I'll try your suggestion when I'm back home later.

 

[CBW]

@ianmcd @CBW
The HW only didn't trigger the boiler to turn on this morning so it does seem that there is a fault with that connection.

Still think it’s the motorised valve. Turn power off for the programmer, should also turn all other controls off. Wait say 10 minutes, turn back on and select a hot water demand, note if it fires up.