Tjernlund DCOP1 Constant Operating Pressure Draft Control 8504174 (Discontinued) - Manual (Page 15)

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HOW THE DRAFT COP WORKS
When an intercepted call for heat contact closure or voltage is sensed at the UC1 interlock terminal strip the COP control is acti-
vated through the UC1 MTR and N outputs. Once powered the COP control energizes the Inducer motor and speeds it up enough
to meet the pressure set point. When the PSA-1 Fan Prover switch closes a 5 second factory set pre-purge delay (Adjustable from
0 to 35 seconds) occurs prior to completing the circuit back to the interlocked heater. The COP will increase or decrease the
inducer speed to maintain set point as flue gas temperatures, volumes and stack effect change. The COP is self compensating for
changes in building pressure and outdoor winds. When the call for heat is satisfied the Inducer will continue to operate for a 2
minute factory set post-purge (Adjustable from 0 to 16 minutes).
VENT PIPE SENSING SAMPLING TUBE & PSA-1 FAN PROVER LOCATION & INSTALLATION
SENSING SAMPLING TUBE LOCATION
The sensing tube should be installed in the cap of a tee or at the rear of a common mani-
fold, in back of the vent connector that is farthest from the Inducer. The tee is necessary
so that only static pressure is measured, (See Diagram A). If the draft sensing tube is
installed in the side of a vent pipe it will also measure velocity pressure, giving an incor-
rect signal back to the DCOP1 Control. If mounting on the side of the pipe is unavoidable,
the sensing tube should be flush to the interior wall of the vent pipe. Avoid sampling near
or in elbows. Vent connections should be sealed to prevent leakage or entrainment.
SENSING SAMPLING TUBE INSTALLATION
1. Using a sharp drill bit to reduce burr, drill a 1/4" hole for draft sensing tube.
Screw sensing tube bracket to pipe with sampling hole centered, (See Diagram B).
2. Insert stainless steel sensing tube through 1/4" hole enough to just penetrate interior
of vent pipe and lock in place with compression nut, (See Diagram B). With the Rooftop
Inducer on, a reading with a draft gauge can be used to determine when interior
of pipe has been penetrated.
PSA-1 FAN PROVER INSTALLATION
IMPORTANT: PSA-1 Fan Proving Switch diaphragm must be
mounted in a vertical position. Firmly insert flexible tubing on
sampling tube and connect with a “T” connector to both DCOP1
sensing port and PSA-1 Proving Switch nipple marked (LOW).
Leave other PSA-1 Proving Switch port open to room atmosphere.
See Diagram J on page 15 for where to install tubing “T”
connectors. Make sure there are no sharp bends or kinks in
tubing.
ADJUSTING THE PRESSURE (DRAFT) SET POINT & BALANCING INDIVIDUAL HEATER DRAFT
Adjusting the COP system is a two step process. In the first step initial rough adjustments are made. This allows time to make fine
tuning adjustments without distractions from the heater(s) firing sequence.
Prior to System Activation
1. Close the balancing baffle in each vent connection riser, (See Diagram C).
2. Adjust barometric draft controls if present to their most weighted or hardest to open position for each heater, (See Diagram D).
3. Turn adjustment screw on PSA-1 Fan Prover Switch counter-clockwise until it stops, (See Diagram E).
D
2D
MINIMUM
PSA-1 FAN
DCOP1 AND
SENSING
PROVER
TUBING TO
BEHIND THE HEATER FURTHEST FROM INDUCER
BE LOCATED TWICE THE MANIFOLD DIAMETER
IF POSSIBLE, THE SENSING TUBE SHOULD
HEATER FURTHEST
FROM THE INDUCER
BALANCING
BAROMETRIC
DRAFT CONTROL
(IF PRESENT)
BAFFLE
DIAGRAM A
DIAGRAM B
1/4” STAINLESS STEEL
SENSING TUBE BEND MUST
FACE UPWARD
COMPRESSION FERRULE
COMPRESSION NUT
SAMPLING PORT CENTERED
OVER 1/4” HOLE
DIAGRAM C DIAGRAM D DIAGRAM E