We were called out to look at a problem with a school heating system last week. One of three boilers was continually cutting out and needed investigating before the schools came back of half term.
The fault was reported by the boiler as an E36 fault which relates to a combustion issue and could be to do with gas pressure, the gas valve, the combustion process or the flue. After testing the gas pressure the main heat exchanger was inspected for blockage, this is done by cleaning out the small gaps between the elements as the video shows:https://atomic-temporary-33033244.wpcomstaging.com/wp-content/uploads/2019/06/IMG_2060.TRIM_.mov
Having given the heat exchanger a good clean out the next step was to set up the gas valve to give out the right level of CO2 which is an indicator of the gas burning efficiency. Once this was set up we then had a level playing field so any faults with the boiler could now be attributed to other parts of the boiler such as the circuit board.
This was the next port of call; to test the voltages out from the circuit board to determine of the correct signals were going to various parts and sensors. It was found that the voltage to the flame detection system was only 36 volts instead of 240v and so this was determined to be the problem.
I swapped the circuit board from one boiler to the other and the E36 fault followed the circuit board confirming that the circuit board was at fault.
A new circuit board was ordered and this will be fitted next week.