Honeywell A4021 Series Product Handbook page 16

ground
G N
ALARM
LINE
NEUTRAL
EARTH
EXTERNAL
RESET
1 2 3 4
NO ext. LINE N
GPS RESET
Fig. 16. Wiring diagram A4021A -- EC7850, post--configuration: intermittent system with 3--valve configuration
ground
G N
ALARM
LINE
NEUTRAL
EARTH
EXTERNAL
RESET
1 2 3 4
NO ext. LINE N
GPS RESET
Fig. 17. Wiring diagram A4021A-- EC7850 with by--pass valve, post configuration
WARNING
These are general wiring diagram and have not been
approved yet by an official approval body. Depending
on the application and used ignition controller special
wiring diagrams maybe required.
(interrupted)
AL L1 FAN RT LD2 PV1 MV
3 4 5 6 7 8 9
P.S.
FAN
5 6 7 8 9 10
N N V2IN V2OUT LGPS / HD IN OUT
ALARM
A4021A
(interrupted)
AL L1 FAN RT LD2 PV1 MV
3 4 5 6 7 8 9
P.S.
FAN
5 6 7 8 9 10 11
N N V2IN V2OUT LGPS / HD IN OUT
ALARM
A4021A
EC7850 with rectification amplifier
flame--
IGN signal HI COM MOD LOW
10 F 12 13 14 15
flame--rod Lock--out switch
ign.
H.D.
L.G.P.S.
gas supply
11 12 13 14 15 16
RBHD VENT HD--OUT V1IN V1OUT
EC7850
flame--
IGN signal HI COM MOD LOW
10 F 12 13 14 15
2--stage
flame--rod
ign.
H.D.
L.G.P.S.
gas supply
12 13 14 15 16
RBHD VENT HD--OUT V1IN V1OUT
15
(intermittent)
C.V. ES2 ES1 ES3 LOS PV2 SHTR
16 17 18 19 20 21
V1
G.P.S.
(intermittent)
C.V. ES2 ES1 ES3 LOS PV2 SHTR
16 17 18 19 20 21 22
LOCK--OUT Switch
V1
L.G.P.S.
EN2R--9023 9705R0--NE
22
V2
PV
LO
HI
V2
Vb
By--pass valve
LO
HI