Carbon monoxide poisoning in a house caused by a gas water heater modification

Energy type: 
Natural gas
Event summary: 
A gasfitter reported a possible carbon monoxide (CO) poisoning incident following a modification he made to the flue of a gas storage water heater.
Accident ID: 
Accident date: 
25 May 2018
Water heater storage
Accident type: 
Carbon monoxide poisoning
Property damage level: 
No property damage
Outcome of investigation: 

A gasfitter reported to WorkSafe Energy Safety an incident where the owners of a gas installation appeared to have been affected by the products of combustion from an improperly flued gas appliance.

The reporting gasfitter had discovered a situation where a hot water cylinder flue was not working correctly and was allowing products of combustion into the home. The gasfitter made a modification to the flue that appeared to have exacerbated this already existing fault.

The gasfitter returned when contacted by the home owners (after they had woken with headaches and dizziness). The gasfitter did not disable the appliance when he reverted it back to its original state, thus reconnecting a potentially dangerous gas installation to the gas supply. (The gas appliance was to be replaced with an electric water heater in a few days time).

The gasfitter was acting in good faith but had made an error that could, in other circumstances, have resulted in a far worse outcome. Energy Safety decided to issue the gasfitter with an infringement notice.