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PRE-INSTALLATION
3
PRE-INSTALLATION
3.1
Cleaning primary systems
CAUTION: MAINS SUPPLIES
▶ Isolate the mains supplies before starting any work
and observe all relevant safety precautions.
NOTICE: Before installation
▶ All the following Pre-Installation sections must be
read and requirements met before starting boiler or
flue installations.
NOTICE: Water treatment
▶ Debris from the system can damage the boiler and
reduce efficiency. Failure to comply with the
guidelines for the use of water treatment with the
appliance will invalidate the appliance warranty.
BEFORE CLEANING THE SYSTEM:
▶ Ensure that the system and pipe work is in good working order.
▶ Where possible keep the existing boiler/circulating pump in
place when flushing the system.
FOLLOW THE GUIDANCE OF BS7593:
Treatment of water in domestic hot water central heating and also the
flushing guidelines below.
NOTICE: ARTIFICIALLY SOFTENED WATER MUST NOT
BE USED TO FILL THE CENTRAL HEATING SYSTEM.
FLUSHING THE SYSTEM
▶ Fill the system with cold water and check for leaks.
▶ Open all drain cocks and drain the system.
▶ Close drain cocks and add a suitable flushing agent compatible with
aluminium at the correct strength for the system conditions in
accordance with the manufacturer's instructions.
The pH value of the system water must be less than 8 or the
appliance guarantee will be invalidated.
▶ Circulate the flushing agent before the boiler is fired up.
▶ Run the boiler/system at normal operating temperature as directed
by the manufacturer of the flushing agent.
▶ Drain and thoroughly flush the system to remove the flushing agent
and debris.
▶ It may be necessary to use a power flushing machine to aid the
cleansing procedure in some circumstances.
▶ Close the drain cocks and refill with fresh water and a suitable
inhibitor.
▶ Vent any air from the boiler and system.
INHIBITOR
Add a suitable inhibitor or combined inhibitor/anti-freeze, if the system
is exposed to freezing conditions, to the heating system in accordance
with the DWTA code of practice and manufacturer's guidelines.
WARNING: Sealing agents
▶ The addition of sealing agents to the system water is
not permitted as this can cause problems with
deposits left in the heat exchanger.
10
Water treatment products
Suitable water treatment products can be obtain from the following
manufacturers:
FERNOX
0870 601 5000
www.fernox.com
SENTINEL
0800 389 4670
www.sentinel-solutions.net
Table 10
3.2
Mains supply
3.2.1
Gas supply
To ensure that the equipment is in good working order and can meet the
gas flow and pressure requirements, in addition to the demand from any
other appliance being served, the following applies:
• Boilers using Natural Gas (NG) must be connected to a governed
meter.
• Liquid Petroleum Gas (LPG) must be connected to a regulator.
• Installation and connection of the gas supply to the boiler must be in
accordance with BS6891.
• Gas pipe sizing should be calculated to ensure no more than the
permitted mbar drop between the meter/governor to the appliance
inlet. ( Commissioning section)
• The meter or regulator and pipe work to the meter must be checked,
preferably by the gas supplier.
3.3
Water systems & pipe work
PLASTIC PIPE WORK:
• Any plastic pipe work must have a polymeric barrier with 600 mm
(minimum) length of copper or steel pipe connected to the boiler.
• Plastic pipe work used for underfloor heating must be correctly
controlled with a thermostatic blending valve limiting the
temperature of the circuits to approx. 50°C.
The pipe work from the boiler to the blending valve must be in copper
or steel (protected from corrosion).
CONNECTIONS/VALVES:
• All system connections, taps and mixing valves must be capable of
sustaining a pressure up to 3 bar.
• Radiator valves should conform to BS2767:10.
• All other valves should conform to BS1010
• On new installations, or extensions to existing systems where a
radiator previously did not exist, each radiator should be fitted with a
TRV, except the one fitted in the same room/area as the thermostat.
• On boiler only replacement jobs, it is recommended, (but not
mandatory,) to fit a TRV on each radiator.
• An automatic bypass may be required, (downstream of the pump), in
order to maintain the minimum flow-rate through the appliance.
• A drain cock is required at the lowest point on the system.
• An air vent is required at the highest point on the system.
A - Diverter Valve
B - Automatic Bypass
C - Radiator Valve (Flow)
D - Lockshield Valve (Return)
E - Extra expansion Vessel
• The sealed system must be filled using a WRAS approved filling loop
or comply with the diagram opposite for System fill
• Where the system volume is more than 100 litres or exceeds 2.65
bar at maximum heating temperature an extra expansion vessel (E)
must be fitted as close as possible to the appliance in the central
heating return.
• Pressurize the extra expansion vessel (E) to the same figure as the
expansion vessel built into the appliance
• Do not use galvanised pipes or radiators.
6 720 815 724 (2015/11)
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