Heating Won't Switch Off! Help!

[leveller]

Hi,

The other day I noticed my radiators were scorchio, so I turned my thermostat down and left it a while. That night I realised the temperature was actually rising and it had gotten to 23.5C, my thermostat was set to 20C ...

I went up to the airing cupboard and switched off the heating slider on the timer, I then went outside to the garage where my oil burner is and noticed that the boiler hadn't switched off.

I went back to the airing cupboard and turned off the power switch to the timer. I then checked outside again and the boiler had switched off.

Why is my heating on even though my thermostat is set to a temperature lower than it is and the slider on my timer is in the off position?

How much should I be paying to get this problem fixed?

These are the parts that make up my heating system:

Oil burner
Honeywell thermostat
Honeywell timer
Heatrae Sadia Megaflo
Grundfos Super Selectric
2 port zone valve VAL 228 MV
2 port zone valve VAL 222 MV

 

[Puddle]

Well I am going for the heating motorised valve stuck in open position,may be just syncron motor
But see you have a mega flow pressurised cylinder,so get sorted asap,as if hot water motorised valve passes slightly your repair bill could start in increase

 

[leveller]

Well I am going for the heating motorised valve stuck in open position,may be just syncron motor
But see you have a mega flow pressurised cylinder,so get sorted asap,as if hot water motorised valve passes slightly your repair bill could start in increase

I don't know if this helps you pin-point the problem:

When I put the heating slider into the off position on the timer, I hear the VAL 222 MV valve (to Primary Flow on Megaflo) 'whir' into life and a little 'stick' moves from one side of the valve to the other.

When I put the heating's slider into the off position I get no 'whirring' from either valve.