vaillant ecotec no heating just water

[jaguar66]

Hi guys
Just want a bit of help can anyone help. One of my customers is having a problem with a vaillant eco tec that was fitted some 18 months ago . The boiller works normally on domestic hot water however fails to come on in heating mode no external controls are fitted . The boiler fires up on heating if you press the plus minus button but goes out after 10 mins or so displays code sf.h . If anyone can help it would be much appreciated I am g/s but only fit the things.:77:

 

[jaguar66]

Hi guys just an update the switch on the front of the boiler for controlling the heating was indeed faulty so i have bypassed this with a programmable room stat now all working fine thanks for your help.