26
CONNECTIONS
– PLUMBING
COLD WATER SUPPLY / MAKEUP
All plumbing work must be carried out by a qualified person and in accordance with the National
Plumbing Standard AS/NZS 3500.4 and local authority requirements.
Water Heating Applications (W Models)
An isolation valve and non-return valve must be
installed on the cold water line to the system. An
acceptable arrangement is shown in Fig 4 on page
42.
The cold water supply to a domestic water heating
system must be fitted with a pressure limiting valve
if the water supply pressure exceeds 80% of the
lowest rated relief valve in the system. Refer to
on page 27.
Where a H model is being used to produce hot
water at temperatures above 65
o
C for DHW use in
potable water circuits, the 60PSI (415kPa) relief
valve must be exchanged for a 150PSI (1000kPa)
relieve valve unless an open vented storage vessel
is being used.
The cold water supply pressure must be sufficient to provide adequate flow at the fixtures.
Mechanical, Hydronic and Process Heating Applications (H Models)
The pressure of the makeup supply must be controlled. This may be achieved by the use of a pressure
limiting valve or a header tank which is designed to provide the correct operating pressure for the
system.
Where the water heater is fitted with a 60 PSI (415 kPa) relief valve, the maximum supply pressure
setting must not exceed 330 kPa. The minimum inlet pressure is dependent on a number of factors
including operating temperature, minimum inlet pressure for circulating pumps and system pressure
losses.
If the water heater is being used in an open vented system or is supplied with water from a tank supply
and a pressure pump system is not installed then the minimum supply pressure as specified in
on page 31 must be observed.
Backflow prevention in accordance with AS/NZS 3500.1 may be required, please check with the local
water supply authority for any local code requirements.
A suitably sized expansion vessel must be fitted to a closed heating system to prevent discharge of
system fluid during the heating cycle.
Fig 4: Cold Water Connection Plumbing
