A poorly maintained water heater can be a time bomb – literally!
Water heaters are often taken for granted. Once installed, we tend to forget about them. They sit there and quietly perform their function without much attention. We usually ignore them until there is trouble.
The average life of a residential water heater is 10 years. Some fail in as little as six years and yes, we have seen water heater from the 1980’s that are still working – without leaks. But we always recommend changing your water heater when it reaches the 10 year mark as preventative maintenance.
When water heaters fail they can cause a lot of damage. This is usually caused by rust. You may get home one day to find water running
out from under your garage door. If you don’t have boxes of cherished photographs stored around your water heater, you may escape any real loss. That is the best case scenario. But water heaters can fail with catastrophic and expensive consequences. Hot water can spray out from a ruptured tank and dissolve the drywall around it. Hot water can find its way into your house and ruin flooring, furniture, drywall, computer towers, and anything that may be on the floor.
A more dangerous failure is when the water heater burner does not shut off. Not only can the excess heat set your house on fire, it can also raise the temperature – and thus the pressure – of the water inside the tank which can cause the tank to explode.
That is why all water heaters should must have a safety valve to prevent it from exploding. The valve is called a Temperature and Pressure Relief valve or TPR valve. This valve releases the pressure if it is too great so that the tank does not explode. Unfortunately these valves sometimes leak and homeowners cap them to stop the leak.
Believe it or not we run into modified TPR valves regularly. Here is a picture of a TPR valve that was modified. Whoever did this created a situation that could cause severe injury or death. They installed a spigot into the TPR valve which was turned off. This defeats the whole purpose of the relief valve!
The boiling point of water is 212 degrees F at sea level. However if you heat water in a sealed tank, it cannot boil and just becomes super-heated and the pressure builds. When the pressure builds enough to rupture the tank, the super-heated water instantly turns to steam. This instantaneous conversion from water to steam is amazingly powerful since the volume of water expands 1,600 times when it turns to steam. This rapid conversion of water into steam causes the violent explosions seen in the video below.
Watch the guys from the TV show Myth Busters turn a water heater into a rocket.
In addition to the explosion hazard described above, water heaters can release Carbon Monoxide. This can happen
when the sections of the flue become mis-aligned or separated. The sections of the flue should fit tightly together with the lower sections inserted into the upper sections. The sections should also be connected with three sheet metal screws. In the picture at right you can see gaps in the flue sections.
The drain valve is there to flush the water heater periodically. You can get longer life and better performance from your water heater if you flush it every few months. But if you experience a natural disaster that shut off the water supply, your water heater serves as a convenient source of water.
Water Heater Shell
What you see is NOT the water heater. It’s just the sheet metal shell that surrounds the tank. We have often heard “It looked just fine, then it started leaking.” On the other hand, if the shell is completely rusted, don’t expect the tank inside it to look much better.
About the author: Philippe Heller is the President of The Real Estate Inspection Company, the largest home inspection companies in San Diego. The company puts safety first, and water heaters are a major inspection item. When choosing a home inspection company be sure to pick one that has your family’s safety in mind. If you have any questions, contact the company at email@example.com