help , i have a isar he30 combi boiler the problem i am having is heating is turned off via honeywell cm927 thermostat but the heating remains on . has any one got any ideas why this is happening as i have turned the system off

nev, May 2012

ideal isar HE30
GCN 47-348-30
CH stays ON
2 possible causes
does C* appear on boiler display when CM927 turned off?
[with green LED lit & sometimes flashing red LED]
if YES
then faulty timer receiver unit sending switch live to boiler mains connector
if NO
does "d" appear regularly [when DHW not used]
most likely divertor valve seized

manwithnoname, May 2012