A TPR (Temperature/Pressure Relief) valve usually prevents water heater explosions by providing an outlet for excess system pressure that results from thermal expansion. When this happens, water usually leaks out of the system through the valve.
Most TPR valve leaks are usually a sign of a problem that is related to thermal expansion such as a waterlogged expansion tank or a faulty thermostat that causes the system to overheat. However, there are times when TPR valve leaks are not an indication of an existing thermal expansion-related problem. Here is what you should know.
After allowing hot water to flow through it, the TPR valve should be able to close itself off once the system pressure goes back to normal. Accumulation of debris and dirt in the valve's opening can prevent this from happening. The Temperature/Pressure Relief valve may then continuously leak.
Leaks that have nothing to do with potentially dangerous thermal expansion complications can also happen in cases where the wrong type of valve is installed or in cases where the pressure settings of the valve are wrong. This usually causes leaks mainly because the valve's closing and opening is dependent on a given pressure system pressure being attained. If the set pressure is too low or if the wrong type of valve is used, it may open up even when the pressure of the water heating system is normal.
Water hammer problems
When there is a sudden change in the velocity at which water travels in your water supply lines, there is bound to be sudden fluctuations in pressure. This may then lead to abnormal system increase surges that may then force the water heating system's TPR valve to open. As a result, even though the pressure in your water heater may be normal, these momentary pressure surges that occur as a result of water hammer problems can cause the TPR valve to open up and thus cause leaks.
Leaks into the water heating system
Most water heating systems are closed systems. Any leaks into the water system – from a high-pressure area – is bound to increase the volume of water in the system and hence increase the system pressure. This pressure increase may then force the TPR valve to open up. Therefore, the leak that you are seeing may be as a result of problems such as a leaky coil of a tankless heater or a heat exchanger coil leak, and may have nothing to do with thermal expansion problems.
Knowing that there are other causes of a TPR valve leak could help speed up the troubleshooting process. For example, most TPR valve defects are easier to detect and fix – when compared to faulty thermostat and other defects that lead to thermal expansion. Starting the troubleshooting process by checking for these defects could help save time. Being aware of other causes of valve leaks will also come in handy in helping you identify the source of your problems once you have ruled out the ones related to thermal expansion.
For more information, contact a local company like Aggressive Mechanical Contractors.