According to ANSI-AARST standards, what action should a contractor take if a combustion appliance is backdrafting?

When a combustion appliance is backdrafting, it indicates a serious issue where the appliance is drawing combustion gases back into the living space instead of venting them outside as intended. This situation poses significant safety risks, including the potential for carbon monoxide poisoning and the introduction of other harmful gases into the home environment.

According to ANSI-AARST standards, the contractor should take immediate action to ensure safety and address the malfunction. Shutting off the radon system and seeking maintenance is the appropriate response because it prioritizes the safety of the residents by stopping any potential harmful effects caused by backdrafting. This approach allows for evaluation and repair of the appliance or ventilation system by a qualified professional, ensuring that both safety and radon mitigation efforts can be effectively managed without compromising indoor air quality.

While options like increasing ventilation may seem like a temporary solution, it does not directly address the underlying problem and may not sufficiently mitigate the risks associated with backdrafting. Monitoring conditions while leaving the system running could lead to dangerous situations. Ignoring the issue is never advisable, even if radon levels are currently acceptable, as backdrafting represents an ongoing safety hazard that requires prompt attention.