Health And Safety Regulations 1993; Effectiveness In Combating Legionella - andrews 10/105 Installation And Service Manual

1 General and Safety Information
1.3

Health and Safety Regulations 1993

1.4

Effectiveness in Combating Legionella

It is the duty of manufacturers and suppliers of products for use
at work to ensure, so far as is practicable, that such products
are safe and without risk to health when properly used and to
make available to users, adequate information about their safe
and proper operation.
Andrews Water Heaters should only be used in the manner and
purpose for which they were intended and in accordance with
the instructions in this manual. Although the heaters have been
manufactured with paramount consideration to safety, certain
basic precautions specified in this manual must be taken by the
user.
It is imperative that all users of the heater must be provided with
all the information and instruction necessary to ensure correct
and safe operation.
Water systems in buildings have been associated with outbreaks
of Legionnaires' Disease, particularly in health care facilities
where occupants are significantly more susceptible to infection.
In recognition of the risks in hospitals, a Code of Practice for the
Control of Legionella in Health Care premises has been issued
by the Department of Health (1991). Codes of Practice
applicable to other premises have been published by other
organisations, principally the Health and Safety Executive
(HS)(G70) and the Chartered Institute of Building Services
Engineers (CIBSE, TM13).
All Codes of Practice draw attention to the design and operation
of water systems with reference to avoidance of factors that
favour colonisation by Legionella bacteria. These factors
include stagnation, lukewarm conditions (20°C to 45°C) and the
accumulation of debris, scale and corrosion in the base of tanks
and calorifiers.
Andrews Water Heaters has commissioned an independent
evaluation of their products to investigate their resistance to
build-up of legionella bacteria.
Experiments were conducted to determine whether, following a
substantial challenge by legionella pneumophilia, after overnight
and stagnation conditions, the system was rendered free from
viable recoverable Legionella. It was found that at 61°C,
following a challenge of approximately 107 organisms per litre,
within one hour, more than 99.999% of organisms had been
killed. After a subsequent stagnation period, sampling did not
reveal any residual contamination. The design of the base of the
water heater precludes Legionella colonisation, even after build-
up of debris. The burner positioning ensures that the water at
the bottom of the heater reaches the same, or higher
temperature as in the rest of the heater.
Based on data obtained through experiment, the Andrews Water
Heater can be described as Legionella resistant as it is
considered unlikely that, at the temperature tested, the organism
would colonise the water heater and present a possible health
risk.
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