A.O. Smith TC-099 User Manual

Page 37

VF BOILER SERVICE MANUAL

AOS WPC - Tech Training

36 of 72

Servicing should only be performed by a Qualified Service Agent

PDB - SECTION A

The left side of the PDB circuit board contains a terminal strip (TB1) used to connect the 120
VAC power supply to the boiler, the pump relay, and the pump motor. VW models will have a
factory mounted pump powered by the pump relay; VB models are not equipped with factory
pumps. Review the output specification table (page 69) for field supplied pumps.
Power supply must be dedicated/isolated: 120 VAC, single phase, with a grounded neutral
line, per NEMA standards using a 30 amp dedicated circuit breaker. The power supply must
be in a dedicated conduit. Hot wires, neutral wires, and ground wires must not be shared
with any other appliances including other VF boilers. External control or Tank/Loop Probe
wiring must also be in dedicated conduits. See the power requirements on page 68.

Ground To Boiler

JP2 Jumper

Should be on -

removed during

manufacturing

only

120 VAC Neutral Wire

120 VAC Hot Wire

(From Boiler On/Off Switch)

120 VAC

Power

Supply

Ground Wire From Pump

120 VAC Neutral Wire From Pump

120 VAC Hot Wire From Pump

120 VAC Neutral Wire

Internal

Connections

120 VAC Hot To F2 Fuse

120 VAC Hot From F2 Fuse

To Pump Relay Com Contact

F2 Fuse

20 AMP

(See page 37)

120 VAC Hot Wire From

Pump Relay N.O. Contact

TB1