When you have a tempering valve installed for your hot water storage system, you can expect it to last somewhere between 5-8 years. However, regular inspections and maintenance will prolong its lifespan and identify problems before they can do any damage. Many TMV or tempering valve-related problems stem from a build-up of debris from your hot water unit. Water heaters should be flushed annually to prevent a build-up in your tank, and this will help prevent a build-up in your valve as well. Furthermore, you can have an inline filter installed. This prevents debris from entering your hot water system in the first place! Older hot water systems are also prone to rust and build-ups which can affect the valve.