The CBX7 Control Unit utilizes phase control to set the current on any given Heatizon Systems Transform-
er. The CBX7 incorporates a soft start that will ramp the current on and off from zero to full current in about
two seconds. The soft start eliminates high in-rush current or power surge. The output current is set by
adjusting a potentiometer on the Power Board, and not by using Transformer Taps.
The CBX7 has an SCR fault that opens a relay and turns the system off if the SCR fails, or if the activation
device is off and the system attempts to stay on. Multiple CBX7 Control Units can be connected to a sin-
gle activation device with a Selector Box (Heatizon Part # M329). Heatizon Systems offers a large number
of different sized Transformers that may be used with the CBX7 Control Unit.
There is no power switch on the CBX7 assembly; the panel circuit breaker is used as the power on/off
switch. A disconnect at the Transformer assembly may be desired, or required by the National Electric
Code, local codes or regulations.
STARTING UP A CBX7 SERIES SYSTEM
Before proceeding, make certain that all shorts have been cor-
rected and cleared, all damaged or cut heating element and/or
Cold Lead has been appropriately repaired, and any and all joints
have been crimped, soldered, and tightened where appropriate,
Step 1: Visually inspect the Heating Element and Cold Leads for
cuts, shorts, and other damage; repair as necessary. Check for
continuity to any conductive material, including but not limited to
metal; eliminate as necessary. Record system information in the
spaces provided on the on the Control Unit front cover. Also fill
out the form Heatizon Systems “After Installation Element Test”
found in the Heatizon Systems After Installation element test sec-
tion of the manual. Test system in presence of Architect, Con-
tractor and Owner’s Representative, to be certain system func-
tions in accordance with design intent.
Step 2: On the Power Board, turn R29 Adjustment Potentiome-
ter (see diagram on page 6-9) counterclockwise five turns.
Step 3. Turn the circuit breaker ON, and/or turn the external
power disconnect to the ON position.
Step 4. Attach a clamp-on True RMS Amp Meter to one of the
Cold Leads.
Step 5. Turn the Activation device to the ON position
Step 6. Turn R29 Adjustment Potentiometer clockwise until the
desired current (95 Amps or less) is achieved. Verify that the
Green LED (D-7 on the Power Board) is lit when the
Activation device is calling for heat.
WARNING: If the proper operating
amps cannot be achieved, this could
indicate a problem in the installation of
the heating element or other problem
with the system. Consult your
Heatizon dealer or Heatizon Systems
for further assistance.
WARNING: Danger of shock. Extreme
care should be used to position Trans-
former taps so that they are clear of the
cover or other taps on the Transformer.
Carefully bend copper taps as needed
to ensure proper clearance on both
used and unused taps.
6-8
CBX7 START UP PROCEDURES
The following safety circuits monitor the CBX7 Control Unit to contribute to safe opera-
tion:
SCR Failure. The CBX7 has an SCR fault that opens a relay and turns the system off if the SCR fails, or if
the activation device is off and the system attempts to stay on.
Use the System Operating Tables or Useful Formulas in Section 8 of this Design and Installation Manual to
determine the appropriate secondary Transformer Power Tap.
CBX7 SAFETY FEATURES
