Commissioning The Appliance - Worcester 14/19CBi Installation And Servicing Instructions

12. Commissioning The Appliance

Water Treatment: For optimum performance after
installation, this boiler and its associated central heating system
should be flushed in accordance with the guidelines given in
BS7593: 1992 – Treatment of water in domestic hot water heating
systems. Full instructions are supplied with proprietary cleansers
sold for this purpose. If an inhibitor is to be used after flushing, it
should be used in accordance with the manufacturers instructions.
Suitable flushing agents and inhibitors are available from Betz
Dearborn on 0151 4209563 or Fernox on 01799 550811. Any
flushing agent must be completely removed from the system.
12.1 Remove the outer casing by first loosening the base screw.
Disconnect the earth and lift off the casing.
Check that the electricity and gas supplies to the appliance are
turned off and that all the water connections throughout the
system are tight.
Open any system valves.
Open all the radiator valves. Remove any air vent caps.
If a sealed system has been installed then fill through a WRc
approved filling kit to an initial pressure of 2.5bar.
Check for water soundness throughout the system.
Vent each radiator in turn.
Remove the cap from the pump and turn the shaft about half a
turn. Replace the cap.
Check that the relief valve (sealed system) operates by turning
the knob anti-clockwise until it releases.
12.2 Set the Expansion Vessel Pressure - Sealed System
The charge pressure of an expansion vessel is usually 0.5bar,
which is equivalent to a static head of 5m [17ft].
The charge pressure must not be less than the static head at the
point of connection. The expansion vessel must be charged to
0.3bar less than the initial system design pressure.
Note: 1bar = 10.2m = 33.5ft of water.
12.3 Set the System Pressure
Fill the system initially until the pressure gauge is at 2.5bar and check for leaks.
Release water through the drain cock until the required system
pressure is obtained, up to a maximum of 1.5bar.
Set the pointer on the pressure gauge to record the set system pressure.
If the pressure indicated on the gauge is greater than 2.65bar
when operating at the maximum central heating temperature,
the expansion vessel is too small and a larger vessel must be fitted.
The boiler with a 10 litre expansion vessel can accommodate a
sealed system volume of about 90 litres. Refer to BS7074 Part 1,
BS5449 and Table 9.
12.4 Clock/Programmer
Any controls fitted to the system should be set up at this stage.
12.5 Check that the gas and electricity supplies are turned off.
Connect a pressure gauge to the burner pressure test point on
the gas valve. Refer to Fig. 31.
12.6 Light the Boiler
Switch on the gas and electricity supply.
Set the temperature control knob to maximum and any clocks or
programmer to operate continuously.
The gas supply pipe will be purged by the boiler.
The control will work as follows:
(i) Pre-purge (air) for approximately 20 seconds.
(ii) Spark and gas for approximately 5 seconds
(iii) Purge (air) for approximately 10 seconds
The boiler will attempt to light a maximum of 5 times before
going to lockout. To reset the product turn the control knob
fully anti-clockwise and back.
NOTE: The burner pressure is factory set and may be reset to
match the system requirements. If, after checking that the
supply pressure is sufficient i.e. 19 mbar approx [NG] or 36 mbar
approx [PROPANE] at the gas valve inlet pressure test point, the
required pressure cannot be obtained then contact Worcester
Heat Systems Service Department.
Reset the pressure as necessary by adjusting the screw on the
gas valve. Refer to Table 1 and Fig.31.
Fig. 31. Gas Valve.
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3
5
12.7 Domestic Hot Water
Check that the cylinder thermostat, if fitted, is set to between 55°C
and 60°C.
Check that all external controls are calling for heat and that the
flow pipe to the cylinder is hot after a short period.
12.8 Central Heating
Check that the external controls are calling for heat to the heating
circuit.
Check that all the radiators heat up evenly. If necessary carefully vent.
12.9 Balance the system to give the correct temperature
differential. Refer to Table 3. Refer to Section 7. for bypass
requirements.
12.10 Set the room thermostat to minimum and check that the
burner goes out. Reset the room thermostat and the burner will re-light.
Turn off the gas service cock at the boiler. The burner will go out
but, after a short pause, the appliance will make 5 attempts to
restart sparking for 5 seconds and then 'lock-out'. After 60
seconds carefully open the gas service cock at the boiler, operate
the reset control and observe the burner re-light and follow the
normal sequence of operation. Refer to Fig. 32.
Turn off the gas service cock at the boiler and the electricity
supply to the appliance.
Drain the system while the appliance is hot.
Refill, vent and re-pressurise the system (Sealed System) adding a
suitable proprietary inhibitor. Further information is available
from WHS Technical Information Dept, Telephone 08705 266241.
12.11 Completion of Commissioning
Disconnect the pressure gauge from the gas valve and tighten
the test point screw.
Restart the appliance and check for gas soundness around the
test point screw.
Fix the red arrow on the data plate to show the boiler setting. If
the setting has been altered the adjustment screw should be re-
sealed by a dab of paint to stop un-authorized adjustment.
Refit the casing, reconnect the earth and tighten the clip.
If the appliance is to be passed over to the user immediately
then set any controls to the users requirements.
If the appliance is to be left inoperative in frosty conditions then
set a programmer, if fitted, to continuous and the appliance to
operate at a low temperature under the control of a frost
thermostat, if fitted, to protect remote parts of the system.
The boiler has its own integral frost protection which will also
protect a compact system.
If there is any possibility of the appliance being left totally
unused in freezing conditions then switch off the gas and
electricity and drain the appliance and the system.
Complete the Benchmark Log-book.
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2
1
4
1. Gas valve
2. Solenoids
3. Connector
4. Inlet pressure test point
5. Burner pressure test point
6. Burner pressure adjustment screw
GAS
INLET