S And Y Plan Systems; Existing Installations; New Installations - Worcester 27i System Compact Installation, Commissioning And Servicing Instructions

PRE-INSTALLATION
SEALED PRIMARY SYSTEM:
NOTICE: Artificially softened water must not be used to
fill the central heating system.
• The CH sealed system must be filled using a WRAS approved filling
loop or comply with figure 2 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 (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 figure as the
expansion vessel built into the appliance.
• Do not use galvanised pipes or radiators.
SYSTEM FILL
Heating
return
Hose union
SV
Temporary hose
CV = Check Valve
SV = Stop Valve
SYSTEM MAKE UP
Heating
AA
return
SV
Fill point
Fig. 2 System fill
1
3
Fig. 3 Additional expansion vessel
[1] Appliance expansion vessel - CH
[2] Extra expansion vessel - CH return
[3] Pressure relief discharge
OPTIONAL DIVERTER VALVE
This boiler is designed to operate on a sealed system only. The boiler will
require a second return pipe from the water cylinder to the wall
mounting frame and terminate in 15mm copper pipe.

3.3.1 S AND Y PLAN SYSTEMS

The boiler is equipped with an internal by-pass.
The internal bypass is not intended to be a substitute for
an external system bypass.
An external automatic bypass should be used if the
system flow can be significantly adjusted or stopped by
zone valves and thermostatic radiator valves (TRV).
10
Mains
supply
CV CV
SV
Test point
AA = Auto Air vent
CV = Check Valve
Make up
vessel
CV
1000 mm (39 in)
above the highest
point of the system.
2
NOTICE: Automatic bypass
▶ An automatic bypass valve is required when fitting an
S-plan type system with two-port valves.
NOTICE: Drain cock
▶ A drain cock should be fitted at the lowest point(s) of
the heating circuit and beneath the appliance.

3.3.2 EXISTING INSTALLATIONS

S PLAN LAYOUT
1
M
4
Y PLAN LAYOUT
1
M
SYSTEM LAYOUT WITH OPTIONAL INTERNAL DIVERTER VALVE
(NOT SUPPLIED WITH BOILER)
F F
R R
Cylinder return
Cylinder flow
Heating flow
Heating return
[1] Diverter valve
[2] Radiator valve (flow)
[3] Lock shield valve (return)
[4] Bypass

3.3.3 NEW INSTALLATIONS

S PLAN PLUS LAYOUT
1
4
Greenstar i System Compact - 6 720 807 726 (2013/05)
3
2
3
2
2
3
2
3