25
MULTIPLE INSTALLATIONS
A multiple installation of Solahart 27 litre in-series gas boosters on a single manifold is possible, using a
parallel plumbing arrangement, where large volumes of hot water are required. It is good practice, but not
essential, to install the water heaters in an Equa-Flow
®
plumbing arrangement. The installation may operate
on a dead leg system or a circulated flow and return system.
If a circulated flow and return system is installed, the circulator must be sized and set to provide a minimum
flow rate of 3.0 L/min through the circulated hot water flow and return system and be either thermostatically
and / or timer controlled. The circulator must not be set to operate continuously, i.e. 24 hours per day.
The solar preheat water and hot water manifolds must be designed to balance the flow from each water
heater. To achieve this, there are basic installation requirements and principles which must be followed:
1.
The maximum number of water heaters in a bank should be 6. Only one bank can be installed.
2.
The water heaters must be of the same model.
3.
The solar preheat water line, solar preheat and hot headers and hot water line must be sized to meet the
requirements of both AS/NZS 3500.4 and the application. The gas line must be sized to meet the
requirements of AS/NZS 5601 or AS/NZS 5601.1 and the application.
Minimum header pipe sizes at the installation are:
No of water heaters
1
2
3
4
5
6
Solar preheat and hot header pipe size
DN20
DN25
DN32
DN32
DN40
DN40
Gas pipe size
DN20
DN25
DN32
DN32
DN40
DN40
Note:
Water and gas supply pipe sizes to the installation may be required to be larger than the minimum
pipe sizes at the installation to meet the requirements of the Standards and the application.
The recommended branch line size for the solar preheat and hot water and gas pipes is DN20.
4.
A full flow gate valve or ball valve is not required to be installed on the solar preheat water line to the
system. A non return valve or stop tap must not be installed.
5.
A full flow gate valve or ball valve (not a stop tap) must be installed on both the inlet and outlet branches
of each water heater. A non return valve must not be installed.
6.
An isolation valve must be installed on the gas branch of each water heater.
7.
An adjustable pressure reducing valve (PRV) (RMC model SYR 312 / 20) must be installed on the solar
preheat branch to all but the first water heater.
Each PRV is to be adjusted so that each subsequent water heater is staged to operate only after the
required hot water flow rate increases by intervals of 13 litres per minute (refer to
Valve Commissioning Procedure”
on page 26).
8.
Non return valves or pressure limiting valves must not be installed on the branch lines to the water
heaters.
9.
It is good plumbing practice for all fittings, valves and branch lines to be matched sets all the way along
the manifold.
10.
Sufficient space must be left to enable access, servicing or removal of any water heater.
The water heaters can be installed side by side with minimal clearance between them. The AGA has
approved the installation of the water heaters with an exemption from the 300 mm minimum clearance
requirements between flue terminals, as stated in AS/NZS 5601, clause 5.13.6.5 and AS/NZS 5601.1,
clause 6.9.3.
A second rating label is attached to the inside of the front cover of each water heater. This can be
referenced to determine details of the water heater.
26 for installation and plant layout details.
