Temperature Control Limits
of hot and cold water distribution networks in
public and commercial places has to take into account:
- minimum temperatures to avoid
Legionella development
- maximum hot water temperatures to prevent risk of scalding
• Scalding can occur in many situations in all
types of buildings, both public and private.
Scalds are wholly avoidable and the degree of
potential risk depends on the actual temperature and volume of
hot water delivered and the contact time.
NHS Estates Guidance Note - 'safe' hot water and
surface temperatures provide useful guideline figures.
• Hot water storage: hot water
temperature should be stored at or above 60°C and
distributed to the point-of-use control (TMV) at 55°C or above.
• Cold water supply: cold water
temperatures must not exceed 20°C.
• Final distribution pipes from the
thermostatic mixing valve to the points-of-use must be as short
as practical and in high risk applications NOT more than 2
metres. In lower risk application the maximum length is 5
metres, with water discharged within 30 seconds.
• Recommended maximum outlet temperatures at
point-of-use:
- Bath Fill (see Note 1) 46°C
- Washbasins 41°C
- Showers 41°C
- Bidet 38°C
Hot water delivery temperatures should never exceed 46°C.
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Whilst there is a continuing objective to
harmonise standards across the European community, there remain
significant differences.
1. The recent regulations agree that the best
way to limit Legionella
bacteria development is to produce and deliver hot water
at a higher temperature.
2. The scalding risk in public and commercial
places therefore grows significantly:
- at 55°C: third-degree burns in 100 seconds.
Healthy adult skin will suffer burns in 30 seconds.
- at 60°C: third-degree burns in 5 seconds on
average (shorter duration for a child - at 70°C: less than ONE
second).
Thermostatic mixing valves applications:
- at the boiler outlet to lower the
temperature of the hot water distribution.
- upstream and as close as possible of points-of-use to
avoid any risk of scalding (i.e. 38-46°C).
=================
- Prevents risks of scalding in the high-risk
sector by lowering hot water temperature at points-of-use.
- Ensures a constant temperature at
points-of-use (regulates fluctuations).
Economix 15/3 is licensed for healthcare use
under HP/LP-B, HP/LP-S, HP/LP-W.
Economix 22/3 is licensed for use under
HP-T44.
