honeywell st6400c random mode !!

[grumpyoldgit]

my son has recently moved in to his own house,the central heating seems to go into random mode, mainly not coming on when it should etc . now the the problem is i'm supposed to know how to fix everything!! please guys has any one had this problem? are these controllers iffy? i expect its about 10 years old. thank you from a desperate newby

 

[Elkato531]

These programmers are generally reliable but it could be crackered.

Trouble with having recently moved in is that you don't know the history. Has it ever worked properly? Is it wired up correctly? Is the fault with the thermostats or with the boiler and not the programmer?

You can probably download wiring plans from honeywell if you are confident with electrics but I would get someone in to check it out if I were you.

 

[Burnerman]

Just bought one of these from Tradeplumbing.co.uk £48.44 plus postage. Came in one day! Result