Technical data

Benchmark 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 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
inhibitor manufacturers instructions.
Suitable flushing agents and inhibitors are available from Betz
Dearborn Tel: [phone] and Fernox Tel: [phone].
Instructions for use are supplied with these products.
IMPORTANT: Any system cleanser must be fully flushed from the
system before any inhibitor is added.
12.1 SUMMARY
The appliance is dispatched with the controls set to provide a
maximum output for domestic hot water and central heating
load of 24 kW.
The appliance automatically modulates to satisfy lower heat loads.
Domestic Hot Water Circuit
Confirm that the mains water supply has been flushed out at
installation. If not it will be necessary to disconnect the cold
water inlet pipe from the appliance and thoroughly flush.
Central Heating System
Flush the system before starting to commission the appliance and, at
the end of the commissioning procedure, drain whilst hot.
Immediately refill and re-pressurise adding an inhibitor as necessary.
Gas Service.
The complete system, including the meter, must be inspected and
tested for soundness and purged as indicated in BS 6891. In the event
of a leak, or suspected leak, at the ‘O’ ring joint on the main appliance
manifold, connect a manometer to the test point on the inlet of the
multifunctional gas valve. A soundness test carried out after turning
off the appliance gas cock will test the section between the gas cock
and the gas valve, thus enabling the leak to be traced to the ‘O’ ring.
12.2 APPLIANCE AND CENTRAL HEATING SYSTEM
PREPARATION.
12.2.1 VENT THE APPLIANCE.
Remove the cabinet front panel before starting the
commissioning procedure. See Fig. 14.
Check that the gas service and the electrical supply to the
appliance are turned off.
Raise the facia and control box into the Service Position. Refer to Fig. 14.
Lower the expansion vessel into the Service Position and remove
the inner casing cover. See Fig. 16.
Check that all the water connections throughout the system are tight.
Open the system valves at the appliance. See Figs. 3 and 17.
Open all the radiator valves, fill the system and vent each
radiator in turn.
Vent the heatbank from the manual air vent. See Figs. 16 and 17.
The automatic air vent (fixed to the flow manifold) will vent the
boiler section for sealed systems. Do not replace the inner casing
cover until instructed in Section 12.4 Appliance Operation.
In order to thoroughly vent the appliance and system the
appliance may be operated without gas turned on as follows:
Switch on the electricity supply.
Set the heating temperature control (or, if fitted, Programmer to
Heating and Water) to maximum.
The pump and fan will run for five minutes, a continuous spark
will occur two minutes before lock-out occurs. Reset by turning
the heating temperature control OFF and ON.
Primary water will circulate around the appliance.
Allow the appliance to operate in this condition for a few
minutes.
Set the room thermostat (if fitted) to maximum. The water
diverter will open to central heating and the appliance will
operate. See Fig. 16.
Primary water will now circulate around the central heating
system. Allow the appliance to operate in this condition for a few
minutes. Vent all radiators again during this period until air is
cleared from the system.
When the system has been fully vented set the heating
temperature control to the Off position.
Note: The water diverter valve, in the de-energised condition, is
always open to provide hot water. The controls give priority to
reheating the heatbank following a demand for hot water. If the
valve fails to open when energised to the central heating system,
hot water will still be available.
The valve does not have a manually open position.
Set the temperature controls (or Programmer) to OFF.
Switch off the electrical supply.
The appliance and central heating system should have been
successfully vented. It is important that it is fully vented.
Check the pressure relief valve operates by turning the knob anti-
clockwise until it releases. Water should be expelled from the
discharge pipe. See Fig.15.
12.2.2 SEALED SYSTEMS ONLY.
SET THE EXPANSION VESSEL PRESSURE
The charge pressure of the expansion vessel (as supplied) is 0.5 bar,
which is equivalent to a static head of 5 metres. The charge pressure
must not be less than the static head at the point of connection. See
Fig 6. A Schraider type tyre valve is fitted to the expansion vessel to
allow the charge pressure to be increased if necessary.
SET THE SYSTEM PRESSURE
Fill the system until the pressure gauge shows 2.5 bar and check
for water soundness. Release water from the system using the
pressure relief valve test knob until the System Design Pressure
is obtained up to a maximum of 1.5 bar.
System Design Pressure in bar = Static Head of the System in
bar + 0.3
Note: 1 bar is equivalent 10.2 metres of water
Set the movable pointer on the pressure gauge to coincide with
the indicating pointer, giving a permanent record of the set
system pressure. See Fig. 16.
If the pressure indicated on the pressure gauge is greater than
2.5 bar when operating at the maximum central heating
temperature, an extra expansion vessel must be fitted to the
system as close to the appliance central heating return
connection as possible.
The appliance (as despatched) can accommodate a system
volume of about 104 litres. Refer to BS 7074 Part 1. If the system
volume is in excess of that accommodated by the expansion
vessel fitted to the appliance then an extra vessel must be fitted
as close as possible to the central heating return connection of
the appliance.
Any extra vessel fitted must be pressurised to the same figure as
the integral vessel. If the expansion vessel fails then the specified
replacement must be fitted .
12.3 PROGRAMMER.
Any programmer fitted to the appliance should be set up at this
stage following the instructions sent with the programmer.
12.4 APPLIANCE OPERATION.
12.4.1 Check that the electrical supply to the appliance is off.
Turn the room thermostat (if fitted) to maximum.
Set the temperature controls (or Programmer) to OFF.
12. Commissioning The Appliance
30