Tjernlund CPC-2 Constant Pressure Controller (Discontinued) 8504091 Rev A 03/01 - Manual (Page 8)

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THE THREE MODES OF OPERATION
OPERATION SEQUENCE IN "AUTOMATIC" MODE:
1. The default mode of operation is Automatic. The first call for heat from any of the interlocked appliances will start the venter and
VENTER START-UP will be displayed on the CPC-2. The CPC-2 ramps up the venter to reach the VENT PRESSURE set point
(V SET x.xx InWc or Pa). This must be accomplished within 60 seconds in the Prover "OFF" mode and 120 seconds in the Prover
"ON" mode. As soon as the Vent Pressure set point is reached the control starts Pre-Purge if this option is activated and displays
the IN PRE-PURGE (V ACT x.xx InWc or Pa) message while continuing to adjust the venter to meet the set point. After Pre-Purge
is timed out, the appliance that called for heat is activated and the message APPLIANCE #__ ON is displayed. If the pre-purge
option is not activated this message will be displayed as soon as the Vent Pressure set point is reached. A Pre-Purge is beneficial
to stabilize vent system pressure prior to burner light off.
2. As other appliances call for heat they are staged 10 seconds apart. If the additional flue gas volume or other pressure disturbance
causes the system pressure to be below the set point for over the 10 second staging period, the appliances are not released to
fire until the set point is reached.
3. Once the last call for heat has been satisfied the CPC-2 starts Post Purge if this option is activated and displays the IN POST
PURGE (V ACT x.xx InWc or Pa) message. During the Post Purge cycle the CPC-2 will continue to maintain the Vent Pressure
set point. Once post purge has timed out, the venter is shut off. If the Post Purge option is not activated the venter will shut off
immediately after the last appliance shuts off.
OPERATION SEQUENCE IN "MANUAL" MODE:
Since the Manual mode operates the venter speed at a fixed user set point care must be taken to verify that the vent system draft is
not so high that it would affect proper appliance burner light off. Cycle appliances individually at the venter speed % selected and veri-
fy proper light off. Cycle all connected appliances together to verify that the secondary fan prover closes and no appliances "spill" at
the venter speed % selected. If the venter speed % needed to draft all appliances is too high for proper light off of an individual appli-
ance, disable enough appliances so that the venter speed % is safe in both conditions.
1. The Manual Mode is activated by unlocking the key pad and depressing the MANUAL MODE button once. You can return to
Automatic mode by depressing the MANUAL MODE button any time the key pad is unlocked. The first call for heat from any of
the appliances will start the venter and VENTER START-UP (x% x.xx InWc or Pa) will be displayed on the CPC-2. The CPC-2
ramps up the venter to reach the default venter speed setting of 40%. The secondary fan prover must close within 60 seconds or
a fault will occur. You may adjust the speed setting by depressing the INCREASE or DECREASE buttons. The % speed
selected must be sufficient to make the secondary fan prover or no appliances will be allowed to operate. The CPC-2 will not
allow the venter to operate in the manual mode until the PROVER "ON" mode is activated. If the transducer is operational the
Vent Pressure will be displayed along with the % of venter speed. If the transducer is not operational 0 VENT PRESSURE may
be displayed.
2. Once the secondary fan prover closes, the control starts Pre-Purge if this option is activated and displays the IN PRE-PURGE
message. After Pre-Purge is timed out, the appliance that called for heat is activated and the message APPLIANCE #__ ON is
displayed. If the pre-purge option is not activated this message will be displayed as soon as the % of venter speed setting is
reached.
3. As other appliances call for heat they are staged 10 seconds apart. If the venter speed % is not high enough to keep the
secondary fan prover made as additional appliances fire a PROVER FAULT will occur and the appliances will be shut down.
A "PROVER FAULT" requires a manual reset. See “CPC-2 FAULT MESSAGES” on page 9.
OPERATION SEQUENCE IN "VENTER ONLY" MODE:
1. The Venter Only mode is activated by unlocking the key pad and depressing VENTER ONLY once. In the Venter Only mode the
venter speed can be adjusted but, no interlocked appliances will be allowed to fire.
2. You can adjust the speed setting by depressing the INCREASE or DECREASE buttons. The default speed is 20%.
3. If the Pressure Transducer is operational, the CPC-2 will display the Vent Pressure.
4. You can return to Automatic mode by depressing the VENTER ONLY button again. If the Venter Only mode is not manually
deactivated, the CPC-2 will revert to the Automatic mode after 30 minutes from the last key pressed.
PROGRAMMING THE CPC-2 MODES OF OPERATION
UNLOCKING AND LOCKING THE CPC-2 KEY PAD
To avoid accidental or unauthorized adjustments to the CPC-2 controller a simple access procedure is programmed into the key pad.
To unlock the key pad to make programming changes push (SAVE SETTING) + (SETUP) + (SAVE SETTING) in sequence. This
allows access to enter new controller settings as long as a key is depressed within 60 seconds of the key pad unlock procedure. To
lockout the key pad push (SETUP) scroll to *Lock Out Key Pad* and push (SAVE SETTING).