2
SAMPLE AND REFERENCE PRESSURE CONNECTIONS
PRESSURE SENSING TUBE INSTALLATION LOCATIONS
FOR MECHANICAL DRAFT INSTALLATIONS
The Pressure Sensing Tube should be installed in the cap of a tee or rear of a common
manifold. The tee is necessary so that only static pressure is measured. If the transducer
sensing tube is installed in the side of a vent pipe it will also measure velocity pressure,
giving an incorrect signal back to the Pressure 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.
Typically, draft applications should sample at a point in back of the vent connection that is
farthest from the exhaust fan, (See Figure A).
BALANCING
BAFFLE
SENSING
TUBING TO MPCI
AND PSA-1 FAN
PROVER
BAROMETRIC
DRAFT CONTROL
(IF PRESENT)
HEATER FURTHEST
FROM THE INDUCER
IF POSSIBLE, THE SENSING TUBE SHOULD BE
LOCATED TWICE THE MANIFOLD DIAMETER
BEHIND THE HEATER FURTHEST FROM INDUCER.
2D
MINIMUM
D
FIGURE A
Sensing Tube
Application
Sample Location
MPCI Pressure Port
Reference Pressure Location
MPCI Pressure Port
Exhaust
Bottom of Chase
Connect to Negative (-)
Room at Bottom of Chase
Positive (Port Open)
Draft
Rear of Manifold
Connect to Negative (-)
Heater Mechanical Room
Positive (Port Open)
Open Supply
Mechanical Room
Positive (Port Open)
Adjacent Room
Connect to Negative (-)
Sealed Supply
End of Supply Duct
Connect to Positive (+)
Heater Mechanical Room
Negative (Port Open)
Recommendations based on MPCI Control being installed in the same room as the sample location. If the MPCI is installed in an
adjacent space, pneumatic connections must be made to the open Pressure Ports that are indicated above.