Trin & Stor
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Installation and Operation Instructions Storage Tanks
4
Minerals and nutrients present in the source water and systems materials
Stagnation or low flow characteristic of dead ends in distribution piping systems and storage tanks
Scale, corrosion, and bio film
Tepid water in cold water lines
Water storage temperatures optimal for bacteria growth
Chlorine concentration
Scald Hazard
- Hotter water increases the risk of scald injury. There is a hot water scald
potential if the storage tank thermostat is set too high. Before changing the temperature
setting on the tank thermostat, refer to the thermostat manufacturers recommended settings. Failure to follow
these instructions may result in serious injury or death.
A scald injury can occur when hot steam or liquid makes contact with one or more layers
of skin. Scald severity (degree of burn) is directly impacted by exposure time and
temperature. Refer to Table 1-4. The following basic precautions are common sense:
Young children and elderly adults burn more quickly and should use cooler water.
Never leave a child alone while drawing water in a bathtub.
Test the water temperature before bathing or showering.
Turn cold water on first, then add hot water until the temperature is comfortable.
Thermostatic Mixing Valve
- When the system requires water at temperatures higher
than required for other uses, such as high temperature applications typically greater than
46
o
C (115
o
F), a means such as a thermostatic mixing valve shall be installed to temper the water for those uses
in order to reduce scald hazard potential. Anit-scald devices such as a thermostatic mixing valve allows potable
water to be stored at a higher temperature to limit bacteria growth, and allows water at the tap to be delivered at
a lower temperature to prevent scalds. Failure to follow these instructions may result in serious injury or death.
This appliance is not intended to convey or dispense water for human consumption such
as drinking or cooking.
Legislation and Guidelines
- At the time this document was written, standards and
guidelines regulating the prevention of Legionella in the United States and Canada were
mostly voluntary. The American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.
(ASHRAE) is currently in the process of converting its guideline entitled "Minimizing the Risk of Legionellosis
Associated with Building Water Systems" (ASHRAE Guideline 12-2000) into an official standard. Consult with
your local authorities as to recommended guidelines for controlling Legionella in potable water systems.
Storing water at temperatures >140°F may not be permitted in some States, so check
with the authorities having jurisdictions. In Canada, recent changes to the National
Plumbing Code requires that domestic hot water be stored at or above 61
o
C (140
o
F) and
then mixed down to safe temperatures at the tank outlet.
General Guidelines
- In the absence of a National standard or local codes, the following are general guidelines
for “good practice” on maintaining, monitoring and operating your potable water system:
Store domestic hot water at temperatures > 61
o
C (140
o
F).
Store and distribute cold water at temperatures below 20
o
C (68
o
F).
System supply for uses other than high temperature applications typically greater than 46
o
C (115
o
F) shall be
equipped with a thermostatic mixing valve on the hot water outlet to reduce potential scald hazards.
Clean aerators and nozzles on water fixtures on a regular basis to reduce scale build-up.
Clean storage tanks and remove sediment. Flush storage tanks and piping systems regularly for 10-30
minutes at high water temperatures (depending on guidelines used) to rid the system of sediment and scale
that develops, typically in the bottom of storage tanks where water temperature is coolest; and piping runs
where water can stagnate.
Abandoned water lines should be capped off at the distribution main, not at the most convenient place.
