Hi,
System:
Thermostat = Honeywell T40
Controller = Drayton LP522
3 way Valve = Drayton MA1
Boiler (3 yrs old) = Vailliant Ecotec 428
Issue:
System been working for 3 years fine but now no central heating working but water is normal, the boiler reports S.30 'No heating demand from external controls (clamps 3-4 open)'.
Symptoms:
When I request hot water via the timed function or constant via the controller I get hot water. When I request heating I get nothing at all, the valve on the 3 way mid position valve does not move from water. When this started 2 weeks ago I could get the valve to move to heating only by: 1. Select water, wait 10 seconds, select heating, wait 10 seconds, unselect water, at this point the vale would move to heating. This was the only way to get it to move to heating only. If I wanted heating and water I would as the valve was passing over the mid position select water again. However in the last few days this no longer works and when I try the above it will not move from water to the mid position.
What I have tried:
I removed the mid valve control/motor part and could easily and freely move the valve by hand. I bought a replacement Drayton MA1 mid valve unit and it behaved the same. So I thought maybe the controller so I bought and tried a new Drayton LP522 and it made no difference it is the same. I have checked and reconnected all the wires. The boiler seems fine and is reporting no errors. I have only checked the wires on the thermostat but not yet replaced. I have set the valve to the mid position and locked with the manual override and no heating at all only when I select hot water. I have currently put all the old bits back on the system and using hot water to heat the house.
Help:
Please provide any advice as I have run out of ideas at this stage, any checks/tests I can run, any more information I can provide to help.
NB - I do not have a multimeter
System:
Thermostat = Honeywell T40
Controller = Drayton LP522
3 way Valve = Drayton MA1
Boiler (3 yrs old) = Vailliant Ecotec 428
Issue:
System been working for 3 years fine but now no central heating working but water is normal, the boiler reports S.30 'No heating demand from external controls (clamps 3-4 open)'.
Symptoms:
When I request hot water via the timed function or constant via the controller I get hot water. When I request heating I get nothing at all, the valve on the 3 way mid position valve does not move from water. When this started 2 weeks ago I could get the valve to move to heating only by: 1. Select water, wait 10 seconds, select heating, wait 10 seconds, unselect water, at this point the vale would move to heating. This was the only way to get it to move to heating only. If I wanted heating and water I would as the valve was passing over the mid position select water again. However in the last few days this no longer works and when I try the above it will not move from water to the mid position.
What I have tried:
I removed the mid valve control/motor part and could easily and freely move the valve by hand. I bought a replacement Drayton MA1 mid valve unit and it behaved the same. So I thought maybe the controller so I bought and tried a new Drayton LP522 and it made no difference it is the same. I have checked and reconnected all the wires. The boiler seems fine and is reporting no errors. I have only checked the wires on the thermostat but not yet replaced. I have set the valve to the mid position and locked with the manual override and no heating at all only when I select hot water. I have currently put all the old bits back on the system and using hot water to heat the house.
Help:
Please provide any advice as I have run out of ideas at this stage, any checks/tests I can run, any more information I can provide to help.
NB - I do not have a multimeter
