On-Demand Water Heater Causes Fire in Residential Home

Location: Castlegar
Regulated industry sector: Gas – Natural gas system

Incident overview

In a residential home, a natural gas on-demand water heater was being serviced by an unsupervised apprentice technician. After service, the technician returned the gas water heater to operation without completing the disassembly to confirm it was safe to return to service. Scale buildup restricted flue passages in the heat exchanger, resulting in corrosion that created a hole in the rear combustion chamber. The hole allowed products of combustion to escape and burn internal wiring, the control board and more. The homeowner found smoke and flames coming from the heater.