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YORK INTERNATIONAL

122

FORM 100.50-NOM1 (604)

Service

in man u al). The duct pressure transducer mea sures dif-
fer en tial pres sure between the pressure in the duct and
at mo spher ic pressure. When verifying trans duc er op er a-
tion, the tech ni cian must insert a tee into the pneumatic
tubing to con nect a manometer and ver i fy the pressure
being applied to the transducer. Once this pressure is
known, a com par i son can be made of the duct pressure
vs. output volts DC from the transducer. Table 23 shows
the relationship between the pressure applied to the duct
pressure trans duc er and the output voltage.

Building Pressure Transducer

The building pressure transducer is located in the re turn
air section of the unit. The purpose of this trans duc er is
to sense and convert the static pressure in the building
to a DC voltage. The DC voltage is then sent to the unit
controller and compare against the

Building

Pressure

setpoint

. The control wiring from the trans duc er is fac-

tory wired, but pneumatic tubing must be

eld supplied

and installed (refer to Installation section in manual).
The building pressure transducer measures differential
pressure between the pressure in the build ing and at-
mospheric pressure. When verifying trans duc er opera-
tion, the technician can insert a tee into the pneumatic
tubing to connect a manometer and verify the pressure
being applied to the transducer. Once this pressure is
known, a comparison can be made of the duct pressure
vs. output volts DC from the transducer. A practical and
quick check of this transducer can also be accomplished
by removing the pneumatic tubing lines from both high
and low side connections on the trans duc er. Since both
of the inputs will now be exposed to the same pressure,
the differential pressure will be zero, and output 2.5
VDC according to the Table 24.

ANALOG INPUT OPERATION

This section describes the control operation of the (13)
thirteen analog inputs. These inputs will be used by the
control to monitor and respond to unit temperatures,
pressures, enthalpy, etc. The connection “layout” for
the IO (inputs/outputs) is shown in the Primary Unit
Controller connection map in Figure 21. Notice that the

gure shows the Jack connection designated by “J”, and

the pin num ber located on the inside of the board dia-
gram. The input or output designations are shown on the
out side of the

gure. For example, J11 – 8 is jack eleven

- pin 8 and is AI5 (analog input 5). J13 – 6 is jack 13
- pin 6 and is AI14 (analog input 14). For example, AI5
(J11 – 8) is the input for Outside Air Relative Humidity,
and is used as part of the economizer control scheme.
AI13 (J13 – 8) is the input for Supply Air Temperature,
and is used for control in both the CV and VAV control
schemes. The analog inputs are also in the I/O tables in
Table 33 with descriptions for each input.

Return, Outside, Supply Air and Slab
Temperature

The temperature sensors are RTD sensors that can be
checked with an ohmmeter. Table 22 provides the re sis -
tance values for a given temperature in °F.

Duct Pressure Transducer

The duct pressure transducer is mounted in the return
air section of the unit on the panel wall. The purpose of
this transducer is to sense and convert the static pres sure
in the supply-side of the duct to a DC voltage. The DC
volt age is then sent to the unit controller and com pare
against the

Duct Static Pressure setpoint

. The control

wiring is factory wired, but pneumatic tubing must be

eld sup plied and installed (refer to Installation section

* 2.5 IWC Duct Transducer Available for FlexSys Option

TABLE 23 – *DUCT PRESSURE TRANSDUCER

OUTPUT TABLE

TEMPERATURE SENSOR OUTPUT TABLE

TEMP.

°F

OHMS

RESISTANCE