A recent commercial I saw from Allstate prompted me to look into the hazards of our hot water tank. I came across the following article:
Older homes have the potential of having several hazards related to age but not all of them are obvious. We do not think of hot water tanks as being one of the safety issues in our own homes. Most of us just take the thing for granted as long as it keeps the shower hot and does not make funny noises or leak.
A bulletin from the Washington state labor and industries department alerts residents to the hazards presented by hot water heaters. The bulletin starts out by acknowledging that our residential hot water heaters are "so common and trouble-free that we often take their safe operation for granted". (Washington State Department of Labor and Industries publication F620-048-000 [06-2009]) I know that is how I view my hot water heater.
The bulletin goes on to say that in spite of the trouble free record of safe operation, your water heater can harbor the potential for a serious accident. The bulletin recommends' routine inspection and maintenance to keep the hazard risk to a minimum.
If you are like me, and millions of other users, the idea of regular inspection of the hot water heater for hazardous defects is pretty new and startling. So let's start with a couple of questions: Can a hot water heater explode? The answer is yes it can. The cause of hot water tank explosions is primarily excessive heat. When water temperature is high enough to generate steam you should remember that steam expands and if your tank is corroded from age it will explode much more easily. Steam expands to fill a space 1,700 times the space it would fill as water. For a dramatic example of an exploding hot water tank check out this video: http://www.youtube.com/watch?v=pu3FwgIHsQA
Of course explosion is the most dramatic hazard posed by a hot water tank; other hazards are leaks and the sequence of events that might occur from them. Think scalds, electric shocks, and property damage.
The second question that occurred to me was "what are the warning signs that my hot water tank is a hazard?" The warning sign that is most dramatic and dangerous is steam coming out of the hot water faucet. If steam comes out of your hot water faucet turn off the electric power to the water heater or turn off the valve for the gas if it is a natural gas water heater. Do this first and fast. Then call a qualified technician to replace the thermostat. The thermostat regulates the heat and if it is defective can cause major over heating and a violent explosion.
The Department of Labor and Industries in Washington state recommends' that you get your residential water heater inspected annually. You can get this done by a professional or learn to do it yourself. There are some dangers in conducting the tests but you can learn how to protect yourself if you read the literature that comes with your hot water tank.
Another hazard is the corrosion at the bottom of the tank. Because that seems to be where the worst corrosion occurs it essentially turns your hot water tank into a rocket if it does explode.
The other very real concern about bottom of the tank corrosion is property damage from leaks. You should inspect your tank for leaks at least once a year and more often if it is getting old. It may be hard to detect the leaks when they are small if you have insulation around your tank. Check by touching, getting a bright flashlight and looking, and by inspecting the floor under and around your tank for signs of damage.
Check your temperature/pressure release valve and make sure it operates properly, is not damaged, corroded or leaking and has a properly installed overflow pipe. One of the major concerns with T/P relief valves is the lack of an overflow pipe because the valve is often on top of the water heater and will shoot super heated water of steam directly into your face if it releases while you are near it.
The Washington State Department of Labor and Industries bulletin notes a tragic incident where a child lost an eye when the steam shot into his face. The tragedy could have been prevented with a properly installed overflow pipe.
If you live in rental housing the responsibility for inspecting the tank probably lies with the property owner but you should know what to look for and what the signs of trouble are so you can call the manager or owner before a lurking threat becomes a real danger.