The boiler and burner switch on even though the time clock is switched off?

you can't judge nothing without knowing what system it is maybe just a sticking zone valve.

hi-spec plumbing & heating (essex)
September 2008

Wiring fault - if you have a electronic clock could be its internal switch has fused together first check you have a 3 amp fuse at the main switch. Could be an electrical fault that has fused the internal switch in clock. Electrical safety checks need to be done.

o
September 2008