LINEA 28 FOLLOWING SWITCH ON [HEATING AND WATER] KEEPS CUTTING IN AND OUT ON AN APPROXIMATELY 10 SECONDS CYCLE. PUMP CHANGED NO LOOOSE WIRES, DRY JOINTS THAT I CAN FIND. CANNOT SOLVE PROBLEM.

BRYAN COLE, December 2008

Check this again. If it is EXACTLY 5 seconds ON then 5 seconds OFF, then it will be a fault with the ignition PCB - part No 1837. If this is not the case - check the display temperature, if it is "telling lies" i.e showing a temperature significantly inconsistent with the ACTUAL temp, then it is probably a Primary thermistor fault - best to replace both thermistors though!

freddie, December 2008