Boiler Isolation Valve; Water Systems And Pipework - Bosch WORCESTER Greenstar Heatslave II External 12/18 Installation, Commissioning And Servicing Instructions

▶ Fit a fire valve in accordance with BS 5410. The fire valve [5] should
be fitted externally to the building and appliance with the fire valve
sensor [8] located within the appliance case. A fire valve with a shut
off temperature of 85°C or higher must be fitted to avoid the
possibility of a nuisance shut off. The fire valve must be a minimum of
1 metre from the appliance. A capillary type valve provides a neat and
simple installation, or a fusible link or electrical system may be used.
4.2.5

Boiler isolation valve

▶ Use copper pipe of the correct diameter according to the information
shown in oil supply sections , & .
– If using soft copper pipe (R220) with a compression fitting, an
insert must be used to prevent the pipe from collapsing or
distorting when the fitting is tightened.
▶ Slide nut [1] and olive [5] onto the oil supply pipe [4].
▶ Slide insert [3] into the pipe.
▶ Offer the pipe to the fitting [2] and tighten the nut [1].
1
5
4
3
Fig. 7 Isolation valve bracket removed for clarity
▶ Use flexible hoses to connect to the oil pump.
4.3

Water systems and pipework

The boiler should not be allowed to operate with a return
temperature of less than 30°C when the system is up to
operating temperature.
Oil burners cannot modulate to accommodate a
reduction in heating loads. If the heating load can be
significantly reduced due to TRV's or zoning of the
heating circuits, consideration should be given as to how
short cycling of the burner could be prevented. Burner
run times should remain greater than 2 minutes during
normal operation. A buffer vessel or thermal store
should be considered to prevent excessive short cycling
of a single appliance, or a low loss header could be used
to divide the heating duty between multiple lower output
appliances.
Primary system plastic pipework
• Any plastic pipework used for the CH system must have a polymeric
barrier, complying with BS 7921 and installed to BS 5955 with
1000mm (minimum) length of copper or steel pipe connected to the
boiler.
• Plastic pipework used for underfloor heating must be correctly
controlled with a thermostatic blending valve limiting the
temperature of the circuits to approximately 50°C with 1000 mm
(minimum) length of copper or steel pipe connected to the boiler,
and a 20 K differential must be maintained at 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.
Greenstar Heatslave II External 2022+ - 6 721 843 980 (2022/01)
• All other valves should conform to BS 1010.
• An automatic bypass valve must be connected between the heating
flow and return where TRVs are used on all radiators, fitted 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.
Sealed primary system
• Where the system volume is more than 180 litres at 0.5 bar or
exceeds 2.65 bar at maximum heating temperature an extra
expansion vessel (B) must be fitted as close as possible to the
appliance in the central heating return.
• Pressurise the extra expansion vessel (B) to the same figure as the
expansion vessel (A) built into the appliance.
A
E
B
2
U
P
Fig. 8 Combi boiler sealed system layout
[A] Expansion vessel
[B] Extra expansion vessel
[C] Automatic bypass valve
[D] Drain cock
[E] Appliance
[L] Lockshield valve
[R] Radiators
[T] Thermostatic radiator valve TRV
[U] To filling system
Filling primary sealed systems
Filling the system
▶ The system must not be filled with salt based,
• Filling the system must comply with the method shown in the figure
below.
• The filling point must be at low level and must never be a permanent
connection to the mains water supply.
• Filling loops must be WRAS approved.
SYSTEM FILL
Heating
return
Fig. 9
[CV] Check valve
[SV] Stop valve
R
T
R
L
C
D
6720805209-82.1Wo
softened water.
Hose union
CV
SV
Temporary hose
Pre-Installation
R
T
L
L
R
T
L
L
D
Mains
supply
CV
SV
Test point
11