Viessmann ECV Series Installation And Service Instructions Manual page 47

Ladder Diagram - Vitogas 050, ECV with Honeywell Intermittent Pilot
120V, 60 Hz Less than 12A
N G
R1
S1
HONEYWELL
S8600(H,M)
MV MV PV GND 24V 24V
GND
BRN
PV
24 V
GAS VALVE
SEQUENCE OF OPERATION
1. Thermostat calls for heat.
2. Relay and sequencer are energized with 24V.
3. Relay contacts close.
4. Fan is energized with 120V.
5. Fan develops sufficient pressure to
close pressure switch.
6. After 30 second prepurge, contacts 1,3
of sequencer close allowing 24V to
ignition system.
PA
1
Pump 120V
4A max.
C1R
Blower motor
M
4
C1S
Transformer
120V
24V
40VA
Class 2
PS C2S
1
Q3451A
pilot burner
Ignition
cable
SHL1, SHL2 are closed.
SHL1 Adjustable high limit aquastat
L
SHL2 Manual reset aquastat
2
PA
FRS
R1
C1R
S1
C1S
5
C2S
PS
Fan
1
SHL1
2
Use external relay if pump exceeds 4A.
SHL2
24V Room
thermostat or other
operating control
Caution: Label all wires prior to
disconnection when servicing controls. Wiring
errors can cause improper and dangerous
FRS1
operation. Verify proper operation after servicing.
Note: Burner should not activate
if pressure tube is disconnected from pressure
FRS2
switch.
Refer to wiring label affixed to boiler access
panel. Viessmann reserves the right to
substitute components or wiring methods.
3
Boiler wiring label takes precedence.
Do not connect any external load to the boiler
24V transformer. Use external power source
to power zone valves.
Do not operate boiler without high limit aquastats
wired in control unit.
7. Provided FRS is closed (not activated)
and pressure switch has remained closed,
pilot will spark, light and prove flame,
allowing main burner to operate.
8. Pilot and main burner will cycle off
SHL1 aquastat setting until
thermostat or other operating control
is satisfied.
9. Thermostat is satisfied, ignition system
will de-energize, burner will stop and there
will be a fan post purge of 50 seconds
through contacts 4,5 of sequencer.
Additional Information
(Maximum setting 194°F)
(Fixed setting 248°F)
Pump Aquastat
Pump on at 40°C (104°F)
Pump off at 33°C ( 91°F)
Flame roll-out switch
24V Relay 1
of relay 1
N.0. contact
Sequencer 24V
N.O. contact, upper stage marked
delay on break and make
4,5
N.O. contact, lower stage marked
delay on make and break
1,3
Pressure Switch 24V
Induced draft blower motor
assembly
FIELD WIRING
FACTORY WIRING
Anticipator
setting: 0.9A
47