Cylinder thermostat query

[COURSIE77]

New to this forum but have a quick query. My Cylinder stat failed, hot water was near boiling and any adjustment to the stat did not cause the boiler to switch on or off.
Fitted a new stat tonight (from wickes). Seems to work ok but noticed if the programme timer is off and i turn the stat down to say 30 degrees the boiler fires? Any ideas what might be wrong?
Many thanks

 

[cider]

you havent wired it correctly

 

[COURSIE77]

Ok - i'm sure i followed the wiring diagram - Earth was straightforward.
3 other terminals 1, 2 and 3.
Three wires blue, brown and Black.

Black to 1
Brown to 2
Blue to 3

Pretty sure thats what the diagram shows????? What have i done wrong?

 

[cider]

holy cow numbers mean nothing its what they do that counts. look at inside cover of old stat and compare to wiring diagram of new one

 

[COURSIE77]

Thanks for the advice - sorted it now. Original stat was wired incorrectly and just found out when wired correctly it works ok too!! Found a wiring diagram for old stat on the net and translated this to my new stat. All good now.