My Ariston Eurocombi Boiler has developed an intermittent fault, where it shuts down (flame goes out) for a second or so, then fires back up again, whether supplying hot water or the radiators. This repeats constantly, every 20 seconds or so, whatever temperature the HW or RAD temp controls are set to.
Fault finding suggests an intermittent fault in the boiler output limit thermostat, and temporarily bypassing the 'stat restores normal operation, but is obviously not a safe way to operate the boiler.
Looking at the boiler innards, the design appears to have been modified since the manual was written, in that there's a bracket on the output pipe for the 'stat, but tracing the wiring diagram the 'stat now appears to be integrated in the DHW temperature control, 'ganged' with the DHW 'stat.
Replacing the DHW control would appear to be a high cost, labour intensive task, involving draining-down and dismantling, but simply bolting on a previous-model pipe-mounted 'stat and re-routing the existing wiring would see the job done in a few minutes.
Can anyone see a problem with that idea? Would I need to use a thermal transfer gel/paste when fixing the 'stat? The DHW 'stat appears to be working perfectly, switching hi/lo at the set temperature, but is there a common failure mode which could see the DHW 'stat fail soon, making it worth replacing the control now?
Thanks in advance