Pre-Installation; System Preparation; Artificially Softened Water; Water Systems And Pipe Work - Bosch Worcester 2000 Series Installation And Maintenance Instructions Manual

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Pre-Installation

NOTICE:
Risk of damage to system or appliance!
Before installation
▶ All the following Pre-Installation sections must be read and
requirements met before starting appliance or flue installations.
4.1

System preparation

4.1.1

Artificially softened water

It is possible to have an ion exchange water softener fitted to the cold
water system of the property. However, the appliance requires an
untreated cold water connection taken from the mains supply, before the
water softener, to the primary water filling point of the heating system.
Alternatively there are water softening/treatment appliances that do not
adjust or alter the pH levels of the water. With these appliances it may not
be necessary to provide an untreated water by-pass to the primary water
filling point of the heat system.
NOTICE:
▶ Salt based softened water must not be used to fill the central heating
system.
4.1.2

Water systems and pipe work

Primary system plastic pipework:
• Any plastic pipe work must have a polymeric barrier, complying with
BS 7921 and installed to BS 5955 with 600mm (minimum) length of
copper connected to the appliance.
• Plastic pipe work used for under-floor heating must be correctly
controlled with a thermostatic blending valve limiting the
temperature of the circuits to approximately 50°C with 1000mm
(minimum) length of copper or steel pipe connected to the
appliance.
Primary system/connections/valves:
• Do not use galvanised pipes or radiators.
• All system connections, taps and mixing valves must be capable of
sustaining a pressure of 3 bar.
• Radiator valves should conform to BS 2767:10.
• All other valves should conform to BS 1010.
• It is best practice to fit Thermostatic Radiator Valves (TRV's) to all
radiators, except the area where the room thermostat is sited which
must be fitted with lockshield valves that are left open.
• The circulating pump speed is fixed therefore as system
circulation can be significantly adjusted or stopped by TRV's or
zone valves, a system bypass must be installed to give at least a
3 metre circuit when activated.
• Drain cocks are required at all the lowest points on the system.
• Air vents are required at all high points on the system.
Showers/Bidets:
• If a shower head can be immersed in water or comes closer than
25mm from the top edge of a bath or shower tray spill-over level then
an anti-siphon appliance must be fitted to the shower hose.
• Bidets with direct hot and cold mains water can be used (with the
approval of the local water authority) and must be the over rim
flushing type with shrouded outlets to prevent the fitting of hand held
sprays.
Hot water:
• Taps and mixing valves must be capable of sustaining a pressure up to
10 bar.
Worcester 2000 – 6 721 814 551 (2019/09)
• Hot water temperature and flow rate are affected by the size and
insulation of pipe work making up the distribution system and are
controlled by the hot water tap and the water main inlet pressure. A
mixing valve can be fitted if a more permanent temperature setting is
required.
• If using more than one outlet at once causes water flow starvation, fit
flow balancing valves or Ball-O-Fix valves to the appropriate outlets.
Primary system considerations - Combi & System appliances
Sealed system
• The CH sealed system must be filled using a WRAS approved filling
loop or comply with examples in 4.1.4 "System fill" section.
• Where the system volume is more than 100 litres or exceeds 2.5 bar
at maximum heating temperature an additional expansion vessel [2]
must be fitted as close as possible to the appliance in the central
heating return.
• Pressurise the extra expansion vessel [2] to the same value as the
built-in expansion vessel - refer to the Technical data page.
1
2
3
Fig. 4 Additional expansion vessel
[1] Appliance expansion vessel
[2] Additional expansion vessel
[3] Pressure relief discharge
[4] Heating return
[5] Heating flow
Checking the size of the expansion vessel
To determine whether an additional expansion vessel is required: Follow
the steps below:
▶ Calculate the total system volume (litres).
– Plot a line vertically on the chart ( Fig. 5).
▶ Determine the central heating maximum operating flow temperature.
– Plot a line horizontally on the chart ( Fig. 5).
▶ Determine the pre-charge in the expansion vessel based on static
head, 1 meter = 0.1 bar.
– Static head should be measured between the expansion vessel
and the highest point on the system (top of the highest radiator).
▶ Select a curve from the key below (1-5).
▶ System pressure should be set at 0.1 - 0.25 bar higher than the
vessel pre-charge.
– It must be at least to the minimum on appliances with an analogue
gauge.
– Minimum pressure settings may need to be adjusted to suit on,
appliances with a digital gauge, in the applicable menu function.
– Intelligent filling settings may need to be adjusted to suit on,
appliances with the automatic filling accessory, in the applicable
menu function.
If the dissected lines are in area A then no additional expansion is
required.
If the dissected line is in are B then an additional expansion vessel must
be installed ( Fig. 4).
Pre-Installation
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