Harsco Industrial SC-1500 Owner's Manual page 28

For correct installation of vent
system, read all of these
instructions and refer to vent
manufacturer's instructions.
Failure to use a proper vent
system (types and materials),
as described in this manual
will void the boiler warranty
and may result in rapid
deterioration of the venting
system, creating a health or life
safety hazard.
Faulty vent installation can
allow toxic fumes to be
released into living areas. This
may cause property damage,
injury or death.
N !
OTICE
Relay A, Relay B and Relay C are
rated for a maximum voltage of
240VAC and a maximum current
capacity of ½ Amp. Connecting a
motorized damper which exceeds
the voltage or current capacity of
the relay could cause permanent
damage to the relay.
Motorized dampers must be powered from an external power supply
other than the boiler. The figure below shows a sample installation in
which Relay C is user-selected to operate a
damper. Relay C is normally-open, so when the boiler is in standby, the
combustion air damper remains closed. Once a call for heat is received,
Relay C closes the
120VAC
provides power to the damper motor, opening the damper.
Once the motorized damper is fully-open, its end limit switch completes
the Air Damper Interlock circuit (120VAC) which allows the boiler to
proceed to ignition.
NOTE The NURO control allows the user to allocate Relay A, B
or C for use with a motorized combustion air damper.
The figure above shows Relay C in use for the motorized
combustion air damper. Depending on the user-
configuration, Relay A, Relay B, or Relay C can be
selected to operate the combustion air damper.
TM
P-K SONIC Gas Fired Boiler
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120VAC
circuit (external power supply) which
External power supplies are required
for Relay A, Relay B and Relay C.
Because power is provided from an
external source, the power is still
present when the boiler is turned off.
Check all voltage sources have been
disconnected prior to servicing.
Failure to do so could result in
electrocution, injury, or death.
motorized air