Alpha HE CB28 Instruction
Instructions for adjusting a
replacement printed circuit board
Alpha HE/CB/SY Boiler Range
1. GENERAL
When the Printed Circuit Board (PCB) is replaced the following adjustments must be carried out:a. Adjust the central heating maximum and minimum output.
b. Ensure that the JP1 plug is correctly positioned for the type of gas the boiler is being used with.
MET - Natural Gas LPG - Liquefied Petroleum Gas
d. Ensure that all electrical plugs and connectors are pushed fully home and soundly connected.
Note: Before fitting a new PCB ensure the polarity of the electrical supply is correct by testing the supply, using a
suitable multimeter, as follows:-
Live to Neutral 240 Volts AC
Live to Earth 240 Volts AC
Neutral to Earth zero Volts AC
Note: i) Before fitting the PCB, carefully bend the red and yellow neons through 180° so that they locate into the
control panel - see Fig. 1.
ii) When the selector switch is turned to the reset position, there will be a delay of approximately 30 seconds
before the PCB will reset.
iii) Ignition rate is pre-set and is not adjustable.
2. FIT AND ADJUST THE REPLACEMENT PCB
Refer to the Installation and Servicing instructions for gaining access to and for replacement of the PCB. To adjust the
PCB the gas valve burner pressures must be measured. Loosen the burner test point screw on the gas valve and
connect a pressure gauge. After adjusting the PCB disconnect the pressure gauge, tighten the test point screw and
test for gas soundness using a suitable leak detection fluid.
Set the Minimum Central Heating Output
a. Turn the selector switch to CH and the central heating thermostat to maximum.
b. When the burner has ignited, take a small flat headed insulated screw driver and insert it into the slot in the CH
CAP (potentiometer P4) and turn it ant-clockwise to its minimum setting.
c. Insert the screw driver into the IGN CAP (potentiometer P3) and adjust it until the correct CH minimum setting is
obtained (refer to the instructions supplied with the boiler).
d. Turn the CH CAP back to maximum and check the pressure, re-adjust if required. The PCB is now set.
Adjustment of the Maximum Central Heating Output
The Central Heating Output will normally be set to maximum. However if required, adjust the CH output as follows:a. Set the selector switch to
b. Carefully locate a small insulated screwdriver into the potentiometer P4 (CH CAP) - see Fig. 1, which should be
fully clockwise.
c. To Range - Rate the heating output, the potentiometer can be turned anticlockwise to the required output.
Fully clockwise Maximum output
Fully anticlockwise Minimum output
Half way Approximately 16.1 kW (55 000 Btu/h) for CB24, CB24X, SY24 & HE25
and the heating thermostat to maximum to operate the boiler on central heating.
Approximately 20.5 kW (70 000 Btu/h) for CB28, CB28X, CB50 & HE33
4
5
M2
T1
43 44 45 N
3
M1
M12
3536
37
38
40
32 31 30 29
M13
M10
P3 for
setting
T2
minimum
CH output
Main
PCB
LD2
LD1
JP3 JP2
Carefully bend the neon lamps
through 180° to t into the sockets
on the control panel.
DHW SET
M4
48
46
47
1213
IGN CAP
P3
P4
CH CAP
M5
CH SET
2P1P
MET
JP1
LPG
6M41M
41 4218 1920 2114 15 16 17
25
24
23
22
M7
JP1
MET/LPG
P4
CH CAP
Fig. 1
Alpha Therm Limited.
Nepicar House, London Road, Wrotham Heath,
Sevenoaks, Kent TN15 7RS
Tel: 0870 3001964
email: info@alphatherm.co.uk
website: www.alpha-innovation.co.uk
These instructions have been carefully prepared but we reserve the right to
alter the specification at any time in the interest of product improvement.
© Alpha Therm Limited 2008.
0112653 )07610( :leT - 0002 snoitacilbuP yb dengised dna delipmoc launaM 3/08/D217
Loading...