HAMWORTHY HEATING LTD. PUREWELL AUTOMATIC IGNITION 500001035/G
15
3)
Check setting of both temperature limiter and control
thermostat. The temperature limiter is generally set at
100
°
C from the factory unless otherwise instructed. Set
thermostat to required temperature (normally 82
°
C) and
ensure limits are set on knob if required.
NOTE!
Minimum temperature setting should not be less
than 72
°
C to avoid condensation in the flue if a 22
°
C
system temperature rise is used.
NOTE!
It is generally recommended that the minimum
return temperature to a non-condensing boiler is 50
°
C.
4)
Drop down fascia on the controls housing to reveal
the main terminal rail. Figure No. 12 shows the correct
location of incoming wires. Remove link on terminals
C1 and C2 (black wire) and insert a multi-meter set to
read DC
u
A. Carefully remove high/low terminal link on
terminals C3 and C4 (red/brown wire), this will ensure
burner stays at light up rate (low fire) when fired.
5)
The Purewell fully automatic boiler utilises a low fire
start gas rate ignited by direct spark ignition (DSI), see
Figure No. 14. To ascertain which type of gas valve is
fitted and the method of low fire and high fire adjustment,
refer to Figure No. 15. You should familiarise yourself
with this procedure for use later when required.
6)
If a single header pipe kit is fitted, the run on timer
should be set to 5 minutes. Check that the fuse on pump
terminal rail is fitted and sound.
11.5.1 Procedure for Initial Lighting
Ensure gas service cock is in the “off” position. Replace
2A fuse in fascia. Press lockout button on fascia to re-
set timer (wait at least 15 seconds before pressing again
if lockout neon does not go out. After a delay the spark
should be heard across the electrodes. As the gas
service cock is closed, the controls should go to lockout
after approximately 3 seconds (amber neon on fascia
lit). If the above occurs correctly, open service cock and
press reset button on fascia.
After a delay the ignition ‘click-click’ should be heard and
the main gas valve should energise lighting the main
burner. Turn the control thermostat to the required flow
temperature.
NOTE!
The multi-meter should be reading
at least 1
µ
A.
11.6 Gas Pressure Adjustment and Combustion
Checks
After the boiler has operated for approximately 10
minutes, remove the 2A-control fuse on the fascia. Open
the pressure test point screw on the burner manifold and
fit a manometer (suitable for 30mbar - Natural Gas or
50mbar - Propane). Check low fire (start rate) against
pressure shown
in Figure No. 1 or Appendix ‘A’. If necessary adjust low
fire pressure (refer to Figure No. 15. for relevant gas
valve fitted).
Replace high fire link carefully to drive valve system up
to high fire. Check gas pressure against that shown in
Figure No. 1 or Appendix ‘A’. If necessary adjust high
fire governor to suit. Occasionally this high fire
adjustment can influence the low fire start rate, therefore
remove link and check low fire pressure again. Adjust
if required. Repeat until low and high fire pressures
are as shown in Figure No. 1 or Appendix ‘A’.
The Purewell boiler has been designed to conform with
the requirements of the Gas Appliance (Safety)
Regulations (1992). For Natural Gas the gas pressure
governor control system is configured for a nominal gas
inlet pressure of 20mbar with a maximum inlet pressure
of 25mbar. Larger Purewell Automatic boilers (95, 105
and 120kW) are fitted with a unique flow share gas
valve arrangement. Refer to Figure No. 16 to establish
method of adjustment of the by-pass throttle
arrangement.
NOTE!
The by-pass valve throttle
MUST
be used as a coarse adjuster, the main control
MUST
always be accomplished by the high/low control valve.
For Propane firing boilers, the nominal gas inlet
pressure is 37mbar, with a maximum inlet pressure of
47mbar. All Propane firing boilers are fitted with a low
gas pressure switch (set at 20mbar). Should the gas
supply pressure fall below this level, the boiler
will not
operate. All Propane firing boilers are fitted with a single
gas valve providing high and low control. Refer to
Figure No. 15.
Remove manometer and close pressure test point.
Record all readings for future reference on relevant
commissioning sheet.
Check no flue gas spillage occurs from the diverter:
Ref.
BS 5440
: Part 1 will give guidance if required. Allow
system to warm up sufficiently to check operation of
control thermostat.
11.7 Temperature Limiter (Limit Thermostat)
Check temperature limiter setting. Removing plastic
cover (unscrewing) can achieve this if fitted. Undo
holding nut and withdraw into the controls housing.
Adjust if required and replace in reverse order to above.
A combustion check must be taken when first
commissioning the boiler. A sampling point is provided
in the flue on draught diverter models or inspection door
on Low Line models, which is covered by a small push
in plug which can be removed.
NOTE!
Care should be
exercised if the boiler is firing as the flue can achieve
temperatures, which will produce injury if touched.