MULTIPLE INSTALLATIONS
45
Refer to the diagram on
page
45 for installation and plant layout details.
PRESSURE REDUCING VALVE COMMISSIONING PROCEDURE
The pressure reducing valves must be set and commissioned for each water heater so the water heaters will
turn on and off in sequence when the flow rate increases or decreases to a particular rate. This procedure
can be conducted with either cold water or solar preheated water, however the temperature of the solar
preheated water must be at least 2°C lower than the preset outlet temperature setting of the water heater.
The water heater installation should be sized and the number of water heaters selected to cater for the cold
water temperature in winter and assuming a period of no solar gain without any solar preheated water
available, if the installation is part of a solar water heater system. The climate chart is based on a flow rate
from a shower outlet not exceeding 9 litres per minute and a tempered water temperature of 42°C.
Climate Chart
Number of Shower Outlets
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20
number of water heaters
warm / tropical climate
(20°C inlet temperature)
1
1
1
2
2
2
3
3
3
3
4
4
4
5
5
5
6
6
6
6
number of water heaters
moderate climate
(15°C inlet temperature)
1
1
2
2
2
3
3
3
4
4
4
5
5
6
6
6
-
-
-
-
number of water heaters
cool climate
(10°C inlet temperature)
1
1
2
2
3
3
3
4
4
5
5
6
6
6
-
-
-
-
-
-
Note:
If there are other hot water outlets which may operate simultaneously with the shower outlets, then the
operation and flow rates of these outlets need to be considered and an allowance made when selecting the
number of water heaters for the application.
Note:
An isolation valve and pressure limiting valve are not required on the solar preheat water line to the gas boosters as part
of a solar water heater installation. A full flow isolation valve must still be installed on the inlet branch of each water heater.
TYPICAL INSTALLATION
– MULTIPLE CONTINUOUS FLOW GAS WATER HEATERS