hi.this is my first posting.can anyone help. this boiler is around 4 years old and is now a fully pumped selaed system.it has worked fine until recently when it appeared to start locking out.it may be a coincidence but a week or so prior to this, the flow and return pipe at about 15ft from the boiler developed a leak at the elbow and was repaired using a compression fitting but a freezing kit was used instead of draining the system. i had an engineer look at the lockout problem and he replaced the thermister and the overheat thermostat which bar the first night after the replacement has so far been successful. with winter coming up i am a little nervous and wonder if i should just sit tight or is there anything i should check out. i also have now learned that a thermal paste should have been applied to the thermister which the engineer did not do.i am quite happy to do it myself and wonder if you could advise exactly where on the thermister the paste is applied.
