Water Heater Hazards


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Water Heater Safety: What are the hazards?


There are multiple ways to heat water for a residence or business; electricity, gas, solar or solid fuels. Each system has its benefits, but they all have a similar layout. A typical water heater is comprised of a storage tank, a heat source, input/output piping, an anode rod, and safety systems. Water heaters vary in size and heat source; and their installation is regulated under the ICC (International Code Council) requirements and other regulations and standards to achieve a level of safety for individuals and property.


Electrical water heater systems use submerged heating coils to generate heat. A current overload protection device is connected to the energy supply which controls the maximum current that can pass into the coils; this primarily prevents hazardous electrical problems but can also help prevent run away heating. If the overload protection is tripped the system shuts down and must be manually reset.



Newer gas water heater systems have a need-based ignition source instead of a pilot light system as seen in older models. When water temperatures drop below the preset temperature, gas will flow to the burner for ignition. Pilot lights in comparison continually feed small amounts of gas near the burner to maintain an ignition source for the burner. If the temperature sensor fails to tell the system that the water has reached the preset temperature then the system will continue to burn gas and heat the water creating a dangerous situation called runaway heating.


A second redundant safety system, a requirement by the ICC for all water heaters, is independent of all the other safety systems; this device, which has numerous names, that we will refer to as a T & P relief valve (Temperature Pressure Relief Valve). A T & P valve used to cool the water tank down and relieve pressure by directing overheated water and vapor away from the tank in runaway heating situations. The T & P valve triggers when either the temperature or pressure exceeds a certain limit, these valves generally serve both purposes and release when either criterion is reached. The pressure valve must release steam when the pressure exceeds 25 psi above normal operating pressure or the temperature exceeds 210°F (99°C). The T & P valve is an effective system when it is working properly.


Water heater failures include but are not limited to water leakages, scalding, fires, and explosions. Corrosion generally occurs internally after the anode rod is depleted. The anode is designed to corrode in place of the tank to control oxidation reaction and prevent extensive damage from the initial use through the water heaters intended life cycle. Fires can occur when electrical components like the current protection device failing, supplied gas is not properly ignited or other flammable materials ignite in the presence of the water heater burner. While not common, the failure depicted on a Progressive Insurance commercial and on the Discovery Channel’s show Mythbusters, water heater tanks can over pressurize from a runaway heating cycle and explode. This situation can only happen if both the built-in heating safety systems and the T & P valve fail to operate as designed. Runaway heating situations will create extreme pressures within the tank and result in a rapid release of energy also known as an explosion. If the failure release point is near the bottom of the tank it may become a projectile. Released pressure in this situation can be hazardous for occupants and others nearby but can also create an incredible amount of property damage.



Basic maintenance can help prevent failures. Checking the T & P valve for clogged or stuck components and replacing when it’s malfunctioning is crucial since it is how the tank releases excess pressure. Proper installation and checking reset buttons on the current protection device can help prevent fires. Damage from corrosion leaks are usually preventable with the installation of a proper drain pan system and by replacing the water heater when it has reached the end of its expected life.