TMV Servicing

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.

TMVs must be regularly tested to ensure they operate the way they are supposed to while delivering safe water temperatures between 39°C and 43°C.

Water Treatment Ireland Ltd offers a comprehensive range of services linked to the servicing and maintenance of thermostatic mixing valves. We can also carry out TMV replacement, TMV installation, temperature monitoring and failsafe testing to ensure compliance with Legionella/ water hygiene best practices.

What is the impact of TMVs on Legionella Control?

Controlling the temperature within hot and cold-water systems is one of the most common ways to prevent legionella bacteria. Hot water must be stored at above 60°C as this will kill off any legionella bacteria in the system, and hot water temperatures must reach 50°C at the outlets to manage the risk of legionella bacteria. 

However, these temperatures are too hot for most applications and can result in scalding. So, this is where the two risks namely; legionella risk and scalding risk have to be considered together and a solution found.

TMVs are often used as a solution to prevent scalding but at the same time can also increase the legionella risk if not managed and maintained correctly.

The water in pipework downstream of a TMV being less than 50°C could provide an environment in which legionella bacteria could multiply and therefore increase the legionella risk.  So, it is important to ensure TMVs are installed as close as possible to the outlet to reduce the legionella risk, while also managing the scalding risk.


How often should TMVs be tested & serviced?

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.

The valves need to be checked on an annual basis or at a frequency defined by the risk assessment. It is important to ensure the valves are working correctly and will offer protection against scalding.

Maintenance should take into account local conditions (such as a potential build-up of hard water/limescale) and the risk of valve failure.

In health and social care settings, TMV3 valves must undergo regular in-service tests to ensure they perform correctly. If a valve fails an in-service test, the valve must either be serviced in accordance with the manufacturer’s instructions, or if cannot be serviced it should be replaced.

What is involved in TMV Servicing & Maintenance?

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.

All work is completed in accordance with the Health Protection Surveillance Centre, National Guidelines for the Control of Legionellosis in Ireland, 2009. A full report is presented on the completion of work including a log of each TMV serviced and a photographic record as appropriate

Our experienced technicians carry out in-service TMV servicing and maintenance in 4 stages – each stage is recorded and logged in your legionella monitoring documents.

Visual Inspection

Examine each TMV to identify if the correct specification valve is fitted, good accessibility and if isolation valves are fitted.

Water Temperature

Measure and record the mixed water temperature to ensure it is between 39°C and 43°C.

Failsafe Test

Perform an in-service TMV failsafe shut-off test, isolating the cold water supply.

Clean, Descale & Disinfect

Isolate each TMV and clean, descale and disinfect valve components and fine mesh strainers.

Get in Touch

Regular testing and TMV servicing will help to ensure scalding risks are managed effectively and should be seen as an essential component in and regulatory compliance and legionella control programme.

Contact our team to learn how our expert TMV servicing and failsafe testing solutions can help you maintain water quality standards, safe water temperatures and meet regulatory standards required or your organisation.