Heating will not turn off

[tally100]

Themostat set to 5 degrees but says heating 23 degrees and will not turn off , its a newish stat 2 years old same as boiler which was replaced its a Vaillant Eco tech 613, i have turned off the heating part on the boiler so its cooling down now. I think it is a 3 way valve thats stuck open can that be right ? , we have 2 in the airing cupboard and if i push the rod on them theres no resistance.

Thanks
Tally

 

[petit_pablo]

Heating valve jammed open, possibly both valves.

 

[ianmcd]

you dont have a three way valve as you call it you have two 2 port valves what is called S plan, Petit_Pablo above has given you the correct advice, if your system worked correctly before

 

[tally100]

Hi Ianmcd

Yes i have 2 x 2way valves not 3 way valves, yes worked ok before, i have just put heating on for a bit to warm house and 1 valve the rod has resistance the other is floppy, do you mean the one thats floppy is faulty thanks

 

[tally100]

Heated up house to 18 degrees so far and now both valves has resistance and pull back if pushed to other side.

 

[ianmcd]

The way that the valves work is you will have one for HW and one for CH and when there is no demand, then the lever should have resistance at both, when one has a demand a small motor will open that valve and when fully open it will make an end switch which will tell your boiler to come on, sometimes the motor jams and doesnt return when the demand is switched off it does this by a spring in most cases but not all ,it is common for the end switch to stick even though the valve has closed

 

[tally100]

Sorted and i cant believe what is was !!!!

Rang Central heating firm who installed and service my boiler this morning told him what was happening they said change the batteries in the room thermostat its a Honeywell cm907. It didn't show any low battery alarm anyway changed batteries and lo and behold it works as it should.

No low battery alarm is shocking as i could have paid to have someone come out for nothing

Thanks for your help