TMV Servicing and Back flow Prevention

Thermostatic Mixing Value

A thermostatic mixing valve (TMV) is a specially designed plumbing valve that carefully mixes hot and cold water to control hot water outlet temperatures to safe levels. TMVs are used in health, social care and education environments to protect people by reducing the risk of scalding from very hot water from showers, baths and wash hand basins.

Regular in-service testing of TMVs is essential to ensure they operate correctly, delivering safe water temperatures between 39°C and 43°C. This is the recommended temperature range for hot water outlets where a TMV is installed.

All TMVs should be tested and the results compared to those recorded during the original commissioning stage. Where there is no significant change to the outlet temperature (≤ 2°C) and the failsafe shut-off activates as it should, the TMV is considered to be operating correctly. However, if the water temperature has increased by more than 2°C or the failsafe does not work, a full TMV service plus recommissioning, or valve replacement will be required.

Back Flow Prevention

A back flow prevention device is used to protect potable water supplies from contamination or pollution due to back flow.

In water distribution systems, water is normally maintained at a significant pressure to enable water to flow from the tap, shower, or other fixture. Water pressure may fail or be reduced when a water main bursts, pipes freeze, or there is unexpectedly high demand on the water system (for example, when several fire hydrants are opened). Reduced pressure in the pipe may allow contaminated water from the soil, from storage, or from other sources to be drawn up into the system.

Property owners are responsible for getting the right kind of back flow device installed.

If you’re the property owner, you must ensure that: