Technical Specifications - A.O. Smith VF VB 1000 Service Handbook

TECHNICAL SPECIFICATIONS

Input Power and Circuit Protection:
†
Power Supply Voltage
120 VAC
Power Supply Requirements
Line Protection (MCB)
Line Output (Pump)
24VAC Power supply
24VAC Protection
†. See page 40 for PDB power supply test procedure.
Input Specifications:
†
Temperature Sensors (Probes)
Flame Sensors (2)
High and Low fire
Igniter - Silicon Carbide
AC Line Polarity Sensor
ECO Switch
24 VDC
Enable/Disable Circuit
(Tstat MCB J11 Socket - see
page 28)
Application Warning:
This is a switching circuit;
DO NOT apply any external
voltage or connect any load
(IE: relay coil) to this circuit.
†. Control System Temperature Accuracy: ± 5.4° F (3° C)
AOS WPC - Tech Training
VF BOILER SERVICE MANUAL
108 VAC RMS minimum; 132 VAC RMS maximum.
Below 90 VAC will result in lock out. "Low AC Voltage" error
message will be displayed.
Dedicated 30 amp circuit breaker should be provided.
Voltage across the neutral and ground wires should not
exceed 1 VAC. Dedicated wiring – no shared hot, neutral or
ground wires.
Fused on PDB to 15 amp @ 120 VAC
Fused on PDB to 20 amp @ 120 VAC
100 VA transformer. Below 18 VAC will result in lockout. "Low 24
VAC" error message will be displayed
Fused on MCB to 7.5 amp
Outlet, Inlet, and remote Tank/Loop temperature sensors
(probes). (Display accuracy = ± 5.4° F (3°C)
Wiring to Tank/Loop probe must be in dedicated conduit.
5µA (DC micro amps) current typical. Flame detection failure
occurs under 2.5 µA.
40 to 70 ohms cold; 3.0 to 4.0 AC amps typical - minimum
proving current of 2.7 AC amps.
Detects reversed power connections and unconnected ground
leads on power lines referenced to earth ground.
Normally Closed bimetal thermostat built into outlet probe,
opens on temperature rise @ 244° F ± 5.4° F (118°C ± 3° C)
External control wiring must be in dedicated conduit.
This circuit must be closed or the boiler is disabled. This circuit
can be used to enable/disable boiler with a supervisory control
for: night setback, occupied/unoccupied, freeze protection, lead/
lag of multiple boilers.
This circuit can also be used with a standard aquastat.
If this circuit is used with an external system temperature control
the on board "Oper Setpnt" should be set a minimum of 20°F
higher than external control set point.
When an external control is not used this circuit must be
physically wired together or jumpered to enable operation.
Servicing should only be performed by a Qualified Service Agent
68 of 72 Ashland City, TN © 2007