Fitting Thermostatic Mixing Valves (TMVs) are a way to ensure the constant delivery of hot water at a safe temperature, which can be set by the user to their own comfort. Thermostatic Mixing Valves are common in many different applications including Domestic Dwellings, Offices, Care Homes, Hospitals and Schools.
Schools and nursery schools should ensure children and staff cannot be scalded by hot water by fitting fail-safe TMVs on hot water outlets.
Thermostatic Mixing Valves blend hot and cold water to ensure water is supplied at the right temperature to each outlet. With TMVs in place you can safely store water at over 60 Degree Celsius which will kill almost all traces of Legionella as required for L8 compliance and still ensure that the water is safe for use. Most Thermostatic Mixing Valves operate using a wax capsule which also acts as a safety feature if cold water supply should be lost, if a total loss of cold water should occur the valve will shut all supplies to the hot taps, thus protecting the user from scalding.
Local authorities may also refer to ‘Building Bulletin 87, 2nd Edition Guideline for Environmental Design in Schools’, which recommends a maximum hot water temperature for school wash basins of 43°C (this would mean TMVs being set to 41°C to account for a possible ± 2°C range of accuracy – the TMVA and BRE also recommend 41°C as the maximum). However, 41°C or 43°C may be too hot for children to comfortably wash their hands. Therefore, the risks of children not washing their hands should also be taken into account in a risk assessment, meaning a school may choose to set TMVs at a lower temperature than the maximum recommended by Building Bulletin 87 and other guidance.
Regulations demand them on baths and showers, but they should also be fitted to hand basins. A scale-resistant unit should be selected for installation on both high and low pressure systems, and certified to the Buildcert TMV2 scheme.
A TMV2 is acceptable in all schools and nurseries except those used by the severely disabled; these require a valve to be rated to the higher TMV3 standard.
For more advice on regulating maximum hot water temperatures, see Building Research Establishment (BRE) Building Bulletin 87 (2nd edition) and The School Premises Regulations/National Minimum Care Standards Section 25.8.
It is important that after fitting TMVs or carrying out other alterations the hot or cold water systems that the schools L8 water risk assessment is updated to clearly show these are in use and included on the diagrams.
The maintenance staff should also be aware of locations so they can ensure when carrying out the water temperature checks these are taken from the hot water inlet to the TMV and not the tap.