Honeywell, as a manufacturer of water valves and heating controls, believes that all existing bath and shower installations in public commercial and residential premises should be upgraded to provide the same protection for scalding hot water as is required in new homes — which can be achieved by fitting failsafe Honeywell thermostatic mixing valves (TMVs) in the supplies to hot-water outlets.
From October 2009, an amendment to Part G of the Building Regulations requires householders to install TMVs on baths and showers.
In healthcare, TMVs certified to BuildCert TMV3 (such as Honeywell’s TM200VO) must be fitted.
Valves to the domestic TMV2 standard (such as Honeywell’s TM300) are acceptable for most other premises. However a risk assessment must be carried out to determine if facilities are used by vulnerable people. If so, TMV3 valves should be installed to provide a higher level of safety.
The BuildCert TMV scheme recommends maximum temperatures for all premises: 46°C for bath fill; 41°C for showers and washbasins and 38°C for bidets.
While 46°C is the maximum temperature for water from a bath tap, it takes into account the margin of error inherent in TMVs and temperature loss in metal baths, especially in cold bathrooms. However, it is not a safe temperature for use. The British Burns Association recommends 37 to 37.5°C as a comfortable temperature for children. In premises covered by the Care Standards Act 2000, the maximum water-outlet temperature is 43°C.