Lx – WH Series Installation and Operation Instructions
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Trinity Lx
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Safe Temperatures for Potable Water
Two factors used to determine safe hot water temperatures are Legionella and scalding. Potable water needs to
be stored at temperatures hot enough to limit the growth of Legionella, yet be cool enough to prevent scalding.
Since both hazards present a potential risk to the user, they must be monitored and controlled. Table 10-1
indicates how water temperature affects Legionella bacteria and contributes to scald injury. Use of a thermostatic
mixing valve in the water heater plumbing system can help protect against both of these hazards. By storing
potable water at higher temperatures, bacteria growth is controlled, while still providing high temperature water
for dishwasher applications and low temperature water for bathing. Before proceeding, read the following
carefully and take all necessary pre-cautions to avoid potential illness and/or injury that can result from
Legionella or scalding hazards.
Legionella Hazard
- This bacteria
is naturally occurring in surface water and ponds.
It
can also be found in man-made water systems around the world such as water storage
tanks, water distribution systems, fountains, hot tubs, humidification systems,
refrigeration systems and grocery produce misters. Health authorities agree that
Legionella bacteria most often enter the lungs due to aspiration when contaminated water
spray is breathed in as opposed to ingesting drinking water contaminated with the
bacteria. Typical illnesses attributed to Legionella include flue like symptoms (Pontiac
Fever) and a potentially fatal type of pneumonia (Legionnaires’ disease). Failure to
follow instructions may result in illness or death.
High Risk Application
- Combination space heating systems can present a significantly
higher risk of developing Legionella than dedicated domestic hot water systems,
especially during non-heating seasons or low temperature water applications. Using
higher temperature tank water, routinely maintaining your water system, and having your
water tested annually are considered "good practice" when it comes to controlling
conditions that contribute to Legionella. See Table 10-1. Failure to monitor and maintain
your combination space heating system may result in illness or death.
Contributing Factors to Legionella
- Experts acknowledge that Legionella is an identified risk in most water
systems. Although eradicating Legionella is improbable, pre-cautions can be taken to control and monitor
conditions that promote bacteria growth. According to the World Health Organization (WHO); American
Society of Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE); Canada Safety Council
(CSC); and Centers for Disease Control (CDC), contributing factors to the growth of Legionella in potable
water systems include:
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 10-1. 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.
