PART G · Water and sanitation
Hot water safety and the 48 degree bath limit
Hot water needs to be hot enough for the system's intended operation and controlled so that users are protected. Part G addresses both system safety and, where the relevant requirement applies, the temperature supplied to a fixed bath. These are related but different issues.
What does the 48 degree limit mean
The Part G guidance provides for a maximum bath supply temperature of 48°C in the relevant dwelling situations. Do not apply that figure as a blanket maximum for the temperature stored in every hot water cylinder or delivered to every outlet.
The installer should explain how the applicable bath-temperature requirement is met without compromising the rest of the system.
Is turning down the cylinder enough
Do not adjust a system's storage or safety settings based on a single online temperature figure. Appropriate storage, distribution and outlet control need a coordinated design.
A thermostatic mixing arrangement may be part of the solution. It needs suitable installation, commissioning and maintenance, not just inclusion in a product list.
What about unvented cylinders
Ask how excess temperature and pressure are controlled and where safety discharge is routed. The discharge arrangement is an important part of the installation.
Use an installer with the appropriate competence and establish the building regulations certification route. A correctly fitted bath tap does not demonstrate that the cylinder protection is adequate.
What records should be supplied
Obtain operating instructions, commissioning information and relevant certification. Ask which components need servicing and what signs should prompt a call to a competent installer.
For a bathroom refurbishment, establish which provisions apply to the actual work. Do not assume that every existing bath must be retrospectively altered to the current new-dwelling guidance.
If water is unexpectedly scalding or a safety device discharges, seek competent advice rather than disabling the control or blocking the outlet.