Tjernlund CPC-3 Constant Pressure Controller Startup Manual 8504125 - Manual (Page 14)

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DRAFT SET POINT ADJUSTMENT:
Once the Inducer is active and the “INDUCER SETUP” screen is visible, simply press the SET POINT key and the Set Point window
will open on the bottom line of the display. Use the INCREASE and DECREASE keys to make the new Set Point adjustment and
press the SAVE SETTING key. The new set point will be displayed on the top line under the SET POINT field. To exit from the Set
Point option back to the setup menu, simply press the SET POINT key again
Press the SET POINT key.
(Set Point window will open on the bottom line of the display.)
Press the INCREASE and DECREASE keys to make the Set Point adjustment
Press the SAVE SETTING key to save the new set point.
Press SET POINT to exit back to setup menu.
BALANCING DRAFT OF HEATER(S)
1. Turn ON the service switch to all of the heaters.
2. Momentarily cycle each heater to verify that the Amber BURNER STATUS CALL LED on CPC-3 for each heater illuminates. If not
verify that wiring conforms to appropriate heater interlock wiring diagram.
3. Verify that all balancing baffles or blast gates are in the closed position. Adjust barometric controls (if present) to the most closed
position.
4. Fire each heater individually, starting with the heater farthest from the Inducer / C.A. Blower. Slowly open balancing baffle or blast
gate until the specified draft is achieved. Barometric draft controls should be closed when the heater is operating within its specified
draft range. Adjust weight on barometric draft control so that it does not open until the manufacturer’s recommended maximum
draft is reached. If additional draft is needed increase the set point on the CPC-3 , See “Draft Set Point Adjustment”, above.
5. After adjusting draft levels on all connected heaters fire heaters in random order and simultaneously to verify draft levels remain
within the manufacturer’s specified range prior to ignition and during operation. Note: The CPC-3 will stage the firing of interlocked
heaters when more than one call for heat signal is simultaneously received by the CPC-3. In general, each successive heater will
be released after the CPC-3 set point has been reached and a 10 second time delay has occurred.
COMBUSTION AIR MODES OF OPERATION
The CPC-3 features two combustion air software modes. The "Open" mode is for maintaining the pressure within the mechanical
room. The "Sealed" program is for maintaining pressure within a common duct connected to sealed combustion heating equipment.
In general, the "Open" software allows room pressure to be maintained over a smaller scale and has features that diminish overshoot
and short cycling. The "Sealed" mode operates in a more reactive manner; similar to that of the variable speed Inducer software.
The Default combustion air program is the “Open” system. Combustion Air Systems used in the "Sealed" mode must use the TD-2
pressure transducer. Combustion Air Systems used in the "Open" mode must use the TD-3 pressure transducer.
“OPEN” COMBUSTION AIR MODE:
The “Open” mode is the most common method of supplying combustion air to the heaters by ducting combustion air directly into the
mechanical room. The transducer references a pressure outside of the mechanical room, such as an adjacent room or in rare cases,
outdoors. In both cases the goal is to reference static pressure so do not sample pressures at locations that can be affected by fre-
quently opened doors, elevator shafts or ventilation fans and diffusers. The model IPS-1 may be used to sample indoor reference
pressure. It reduces the effects of air movement on the sampling tube and provides a finished look. Varying wind speeds will affect
outdoor reference pressure and are difficult to neutralize. The model WW-1 may be used to help neutralize the effects of winds. For
best performance mount the WW-1 at least one foot away from an outside wall.
If the pressure in the mechanical room drops below the set point due to the air consumed by the heaters, combustion air will be sup-
plied. WARNING: Make sure the mechanical room is sealed from the rest of the building. Leakage of the supplied air to the rest of the
building may result in combustion air faults due to the pressure not being maintainable. Don't sample pressures at locations that can
be affected by frequently opened doors, elevator shafts, ventilation fans and diffusers. The CPC-3 set point pressure range for the
“Open” Combustion air system is +0.05" WC to -0.05" WC. The default setting is 0.00". NOTE: “Open” systems must use the TD-3
Transducer.
The Combustion Air Mode is defaulted to the “Open” Mode, or room pressure. Ducted outdoor air directly to burner air inlet(s) requires
the “Sealed” mode of operation.
Press the SET UP key under the Combustion Air side of the CPC-3 keypad to open SET UP menu.
Press the INCREASE key until "SET MODE" appears in the bottom line of the display.
Press the SAVE SETTING key to change display to "SEALED".
Press the SET UP key to escape out of the SET Up menu.