Potterton Derwent Compact Plus Installation, Operation & Maintenance Manual page 19

POTTERTON COMMERCIAL PRODUCTS DIVISION
INSTALLATION, OPERATION AND MAINTENANCE MANUAL
DERWENT COMPACT PLUS - CONDENSING
and not on pump overrun if the boiler has been fired
previously.
Check that the pilot gas cocks and electrical supply
are turned off.
Set the boiler control thermostat to the required
position and the time clock to the 'ON' position. Check
that the high limit thermostat has not been tripped by
removing the hexagon cap nut and pressing the
button beneath it.
Start the boiler by switching on the main isolator and
the on/off switch on the boiler control panel fascia and
the boiler will attempt to light. After a delay (pre-purge
time) of approximately 40 seconds the ignition spark
should be heard and after 5 seconds the control box
should lock out.
If the ignition spark is not detected or the control box
does not lock out see Fault Finding
Commissioning Live Run
1 Turn on the appliance isolation valve.
2 Check the inlet pressure, which should be at least
20mbar, on the inlet test pressure point and note
the value.
3 Close the pilot supply gas cock and check that the
pilot pressure is zero and not moving.
Turn on the electricity supply at the main isolator
4
and at the on/off switch on the control panel
fascia, (ensuring that time clocks and any other
external controls are made or are in the ON
position) also turn on the pilot isolating valve.
5 Approximately 40 seconds (pre-purge time) after
switching on the ignition a spark should appear
followed by ignition of the pilot burner. If the pilot
flame is not established the control box will
lockout in approximately 5 seconds..
6 The control box may be reset after a delay of five
seconds by pressing the reset button on the
control panel and the red light will go out. When
the pilot flame is established check the gas
pressure on the gas manifold pressure nipple and
adjust the regulator if necessary (located on the
gas valve). Turn off the pilot check valve and pull
off the ionisation probe and check that the pilot
and main burner shuts down.
7 Re-connect the ionisation probe and tune on the
pilot check valve and the pilot burner will relight
followed 10-15 seconds later by the main gas
burners.
8 Observe the main gas flame through the viewing
port above the pilot burner, the flames should be
blue and well defined 'V' shaped flame. Then
check the main gas manifold gas pressure and
adjust to give correct burner pressure
9 For high/low operation the high fire rate must be
set first.
With a pressure gauge fitted to the burner
manifold, turn the boiler on and set the gas valve.
Before any adjustment can be made the yellow
cap must first be removed.
Adjust the high fire adjustment screw using an
8mm spanner to turn the adjustment screw,
clockwise to increase and anti-clockwise to reduce
until correct high fire burner pressure is reached.
The low fire rate can now be adjusted by adjusting
the low fire adjustment screw using a screwdriver
(clockwise increases and anti-clockwise reduces
the low fire burner pressure) until a low fire burner
pressure is reached.
Operate the boiler at high and low fire checking
that the burner manifold pressure is correct and
that the flame is stable and blue.
10 Test the gas connection between the ignition valve
and the pilot burner for soundness with a soap
solution or other approved method and seal any
leakages. Switch off the electrical supply and
check that the burner has extinguished. Remove
the pressure gauge from the burner manifold and
replace the sealing screw.
11 Check the reliability of ignition of the boiler by
switching the boiler off using the burner on/off
switch on the boiler control panel. After two
minutes turn the switch back on. The boiler will
now relight. Check that the pilot has a stable
flame and that the main burners light smoothly.
12 With the boiler switched on test for soundness
between the gas valve and the burner manifold
with a soap solution or any other approved
method and seal any leaks.
13 Turn the appliance isolation valve off. The main
and pilot burners should go off. The boiler will
attempt to relight. Check that the ignitor starts
and that the boiler locks out.
Gas Valve Arrangement
Pressure
switch
Valve
Adjustment
under Cap
SECTION 5
PAGE 17
Single stage
valve
DO NOT adjust