30
Mynute
FUNCTIONAL DIAGRAM 28e
NOTE: L-N-E CONNECTION IS ADVISABLE
Key
R.T.
Room thermostat (external controls)
P.S.
Water pressure switch
P.D.S.
Differential pressure switch
H.L.
High limit thermostat
S.R.
Heat thermistor
MOD
Modulator
F
Fan
P
Pump
S.S.E
Sense/ignition electrode
OPE
Gas valve solenoids
B.C.B.
Burner control board
B.E.B.
Boiler control board
D.B.
Secondary board
JP8
Natural gas or L.P.G. selector
Fig. 30
JP9
Timer on/off selector
PT2
Central heating temperature control
PT1
Selection of 0-reset/ winter-summer
DS1-DS2 Temperature/alarm display
TA1
Combustion test
F1
Fuse 100mA F (on 24V circuit)
F2
Fuse 2 A F (on 230V circuit)
RL1
Ignition relay
RL2
Pump relay
IS01
Fan triac
L1
Led OK (green)
L2
Led alarm (blink red)
TRF1
Transformer
G.V.
Gas valve