PlumbRevise
Hot Water SystemsRevision card Premium

Scald risk and the thermostatic mixing valve

Why hot water is stored hot but delivered cooler through a TMV.

Original new-dwelling bath example in England. A hot store labelled at least 60 °C and a cold supply feed a thermostatic mixing valve. The bath supply is capped at 48 °C; a lower outlet limit is required where indicated by the users’ scald assessment.
Scald risk and thermostatic mixing valve schematic

Stored hot water must be managed for hygiene, while the temperature delivered to a user must control scald risk. A thermostatic mixing valve (TMV) blends the hot and cold supplies at the outlet so these temperatures can differ.

Read the full Hot Water Systems note with Premium

You’re reading the free preview. PlumbRevise Premium unlocks the complete write-up, the worked detail for every Hot Water Systems note — plus timed tests on every module.

Plenty of modules are free to read in full.

Something wrong, unclear or out of date? Report an issue with this note.