V

▶ Check the gas supply to the property and the inlet on the gas valve (check drop on inlet).
▶ Check the connections on the gas valve and the board (loose connection).
▶ Check the continuity down harness and replace if required.
▶ Check the voltage to the gas valve (24 V DC approx. when demand).
▶ Check for water on the gas valve connections.
▶ Check the resistance on the gas valve (pins 1–2 approx. 69.5 Ohms).
▶ Replace the gas valve if resistance is incorrect.
▶ If all tests are correct: replace the control unit.