HELP - Central Heating will not switch off

[steveb21]

Setup:


Vaillant Ecotech boiler
Drayton Digistat +3RF




Hot water comes out all the tapes OK
Central heating - well this appears to have a mind of its own!
Last night before bed the honeywell thermostat was displaying temp of 20, i set it to come on at 16 however during the night the radiators were getting heated before the temp dropped to my setting of 16!
So during the day i noticed that whatever i set the temp to, the radiators were comming on at what appears to be random invervals. I switched the honeywell thermostat OFF however have the same symptons, radiators still warming!


Moving over to the boiler...


I have hot water taps in house switched to OFF
Drayton Digistat switched OFF


The boiler cycles through the stages
S.1 Pump Running Heating Operation
S.2 Pump Running Prior to Ignition Heating Operation
S.3 Ignition Sequence Heating Operation
S.4 Burner Ignited Heating Operation


The radiator symbol on the boiler is fixed (it will sometimes start to flash)
There is also a 'C' on the boilers display
Flame symbol will also appear
A timer symbol
a round sort of circle (not sure what this is?)




Running through the service menu i selected:
d.35 Diverter Valve Position 0 = Heating system 1 = Hot Water 2 = Mid Position


Was showing as '0', when i opened hot tap it switched to 2, when i turned off tap it switched back to '0'








Questions:
Should the radiator sign always be on?
With there being no request for hot tap water or heating why is the boiler firing up at random times?
Divertor valve fault? What position should it be set to when everything is OFF ?
The system was working OK prior to the temperature drop a few days ago, could this be linked? anti frost protection valve?




ANy idea's or suggestions ?




Thanks.
Steve

 

[Masood]

Vaillant Ecotech boiler

There is also a 'C' on the boilers display

This symbol means that hot water pre-heat is on. The boiler will fire every now and again to make sure you get hot water quickly when taps are turned on.

Radiators warming up when this happens suggests a faulty diverter valve. As this is an internal component you will need a GSR to investigate further as it involves removing the case.

 

[steveb21]

This symbol means that hot water pre-heat is on. The boiler will fire every now and again to make sure you get hot water quickly when taps are turned on.

Radiators warming up when this happens suggests a faulty diverter valve. As this is an internal component you will need a GSR to investigate further as it involves removing the case.

Hi Masood

could you clarify if the radiator symbol on the boiler LCD should always be there? I believe when it is flashing the radiators are demanding heat?

 

[Chalked]

Sounds like you dugistat has either hot a flat battery ( if it was on when the batteries went, it will stay on)
Or the dugistat receiver is kaput!
Firstly, change the batteries in the stat. After that, Take the receiver off the backplate and see if the boiler stops firing.

As above too, you have hot water pre heat selected. I normally turn that off.

 

[steveb21]

Sounds like you dugistat has either hot a flat battery ( if it was on when the batteries went, it will stay on)
Or the dugistat receiver is kaput!
Firstly, change the batteries in the stat. After that, Take the receiver off the backplate and see if the boiler stops firing.

As above too, you have hot water pre heat selected. I normally turn that off.

I can turn the digistat on and off and there has been no low battery indicator so don't think it's the batteries ?

I got this off the digistat manual;
To switch OFF the thermostat:
"Press the + and – simultaneously for 5 seconds until the OFF is displayed.
The thermostat and heating system will now be OFF unless the temperature in the controlled space falls below 7°C, the frost protection set point. Please note this does not affect the operation of the domestic hot water where provided.
To switch ON the thermostat, press any key to return to auto mode."

The problem I been having has been since the temp has dropped?? The boiler unit is in a non heated garage.

how do I turn off the pre heat? I tried turning the hot water dial fully anti clockwise (the c goes off) and then to midway, however the C returns.