Your water is essentially a large pressure vessel that stores hot water. If you heat your water using gas, you also rely on combustion to generate a flame. Both of these facts make water heaters surprisingly dangerous devices, so manufacturers must install numerous safety features to ensure that failures don't put your home at risk.

Unfortunately, these safety features can also fail, potentially stopping your water heater from working or creating other annoying issues. While these components will typically fail in a way that prevents catastrophic failures, it can still be frustrating when one leaves you without heat. If you're experiencing a problem with your water heater, it may be due to a problem with one of these three safety devices.

1. Flame Sensor

Gas water heaters follow a relatively straightforward set of steps to ignite and begin heating water. When the water heater's thermostat requests heat, gas flows into the burners and ignites. If there's a problem with the burner, gas may flow into the combustion chamber without any flame present. This situation can lead to potentially dangerous gas leaks.

The flame sensor's job is to confirm the presence of a flame and, if it doesn't detect one, shut off the water heater to prevent a gas leak. Flame sensors are relatively simple devices, but they can fail over time or become dirty. A faulty or dirty flame sensor won't accurately detect the flame inside the combustion chamber, causing your water heater to shut down and stop heating your water.

2. Temperature and Pressure Relief Valve (T&P)

Gas leaks aren't the only danger with water heaters. If your burner runs for too long, the water in your tank will expand or even turn to steam. As a result, the internal pressure will increase drastically, leading to an explosion. Fortunately, modern water heater explosions are relatively rare thanks to a simple device: the temperature and pressure relief valve (T&P).

This simple valve allows water to escape your water heater, preventing the internal pressure from reaching dangerous levels. Unfortunately, T&P valves are also a common source of leaks. If you notice the T&P valve on the side of your water heater leaking, you should have a professional check and replace it to ensure this critical safety feature is functioning correctly.

3. Combustion Shut-Off

The combustion shut-off is a unique feature found on certain brands of water heaters. This small, one-use safety device triggers if the burner assembly becomes too hot, serving a similar role to the high-limit switch in a furnace. If the shut-off triggers, the water heater will shut off the air supply to the combustion chamber, preventing the flame from lighting.

Manufacturers install these devices to protect your water heater (and your home) from overheating conditions. If yours triggers, you'll need a trained service technician to determine the underlying source of the problem before replacing the combustion shut-off device. Look into a company like Merrimack Valley Plumbing LLC for more information.