I would have thought if the continuity checks out on the gas valve, the engineer then tested the pcb? We do all phases of residential, and commercial service plumbing. Amazing! i called mcs and they arrived the same day great service and very friendly staff thank you so much! will recommend & will be using you in the future! Many people ask us what a combi boiler does and if it saves money. We are one of the few plumbing companies in chicago committed to their craft enough to own.