Tjernlund CPC-2 Constant Pressure Controller (Discontinued) 8504091 Rev A 03/01 - Manual (Page 5)

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CAUTIONS
1. Failure to install, maintain and/or operate the CPC-2 in accordance with manufacturer’s instructions may result in conditions that
can produce bodily injury and property damage.
2. The safety interlock and system operation performance checks must be performed on each appliance interlocked with the
CPC-2 in accordance with the Auto-Draft® Venter, IN-FORCER Combustion Air Intake, Power Venter or Draft Inducer installation
instructions.
INSTALLATION AND LOCATION OF CPC-2, TRANSDUCER AND BALANCING DAMPERS
MOUNTING OF THE CPC-2
CPC-2 and transducer should be mounted conveniently inside mechanical
room where access is not restricted. Since set up requires adjustment of
draft settings, close proximity to heating equipment is suggested.
MOUNTING OF THE TRANSDUCER
The transducer must be mounted indoors within six (6) feet of the vent or
chimney transducer sampling tube.
MOUNTING OF TRANSDUCER SAMPLING TUBE
The CPC-2 operates best when the transducer sampling tube measures
static pressure, not velocity pressure. The best position to measure static
pressure is in an extension off of the back end of a horizontal manifold,
(See Diagram A). At this position the probe is not influenced by the veloc-
ity of the flue gases being exhausted. Do not use an elbow to connect
the last appliance (furthest from venter) to the common manifold. The
elbow will not allow the sampling tube to measure static pressure. If nec-
essary, “T” off manifold as close to last appliance as possible preferably
using the same diameter pipe as manifold and a clean, burr free transition.
Drill 1/4” sampling hole in vent or chimney for sampling tube. Insert stain-
less steel sampling tube through 1/4” hole just enough to penetrate interior
of vent pipe and lock in place with compression nut, (See Diagram A).
With the Venter on, a reading with a draft gauge can be used to determine
when interior of pipe has been penetrated.
CONNECTING TRANSDUCER TO SAMPLING TUBE
The transducer - negative pressure front port (closest to cover) is connect-
ed to the transducer sampling tube. Make sure the silicone tubing has no
sharp bends or kinks in it. The high pressure rear port (closest to mount-
ing bracket)
must be left open to room atmosphere, (See Diagram B).
BALANCING DAMPER INSTALLATION
Balancing dampers are necessary on each appliance vent riser into the common vent manifold. Since the Venter will pull flue gases
from the point of least resistance, those appliances connected closest to the venter will tend to overdraft. Balancing dampers can be
adjusted to match each individual appliance draft requirement, (See Diagram A). Care should be taken so balancing dampers do not
interfere with flue dampers if on equipment. Tjernlund’s ABD-Series (4-10”, 12” & 14” diameter) balancing dampers are constructed
out of 304 stainless steel and feature a tamper proof locking adjustment.
CPC-2 CIRCUIT BOARD FEATURES
Two closed loop channels allowing independent variable speed control of both venting and combustion air systems.
Two appliance interlocks for control circuit voltages between 18 & 240 VAC plus two sets of dry contacts for activation by gas pres-
sure switch or boiler sequencer dry contacts. Additional appliances can be interlocked by using the optional EXP-4 expansion board.
Up to three EXP-4 expansion boards can be connected to interlock up to 14 appliances into a single CPC-2.
Switchable 120/230 VAC 50/60 Hz. fused power supply.
Dry Contact alarm circuit that reacts to motor high limits, tilt switches, prover faults, under pressure conditions.
LED lights displayed for Venter Check circuit, appliance call for heat, prover circuit completed and CPC-2 power supplied to board.
See CPC-2 Circuit Board Call Outs for LED indicator light status.
Serial Port interface.
All sensor connections to the CPC-2 control must only be connected to Tjernlund approved components. Failure to install, maintain
and/or operate the CPC-2 in accordance with manufacturer’s instructions may result in conditions that can produce bodily injury and
property damage.
DIAGRAM A
COMPRESSION NUT
COMPRESSION FERRULE
SAMPLING PORT CENTERED
OVER 1/4” HOLE
1/4” STAINLESS STEEL
SAMPLING TUBE BEND MUST
FACE UPWARDS.
INDIVIDUAL APPLIANCE
BALANCING DAMPERS ARE
NECESSARY.
MAKE SURE
THEY DO NOT INTERFERE
WITH FLUE DAMPERS.
DIAGRAM B
FRONT NEGATIVE PRESSURE
PORT CLOSEST TO JUNCTION
BOX COVER MUST BE CONNECT-
ED TO SAMPLING PORT WITH
SILICONE TUBING.
REAR HIGH PRESSURE PORT
CLOSEST TO MOUNTING BRACK-
ET MUST BE LEFT OPEN TO
ROOM ATMOSPHERE.