Reznor YDSA Unit Installation Manual - Manual (Page 33)

Form I-Y, P/N 273646R6, Page 33
8.2 Supply Fan
Control
The main controller is programmed to control the fan to operate the unit in two modes:
Occupied and Unoccupied
The supply fan (blower) starts/stops automatically through a local time of day schedule
or remote contact closure commanding the system to occupied mode. If the controller
is connected to a building automation system, other external controllers can control the
mode of operation.
Upon a command for occupied mode, the supply fan starts and runs continuously.
There is a differential pressure (air proving) switch that indicates proof of fan operation.
The supply fan is subject to safety devices, such as duct high limit switches, fire alarm
relays, smoke detectors, low temperature limits, fan status, and other devices which
can turn the supply fan OFF.
If the unit is in the unoccupied mode, the supply fan is turned OFF and will only run
intermittently to maintain night setback/setup space conditions.
Pressure Tubing Color Codes
Pressure Tap Std or Optional Color
Supply Fan Pressure Tap (High Side) Standard BLUE
Inlet Plenum Tap (Low Side) Standard CLEAR
Exhaust Fan Ring Tap (High Side) Option PE or EW YELLOW
Exhaust Fan Inlet Plenum Tap (Low Side) Option PE or EW CLEAR
Dirty Filter Switch - High Side Option BE18 RED
Dirty Filter Switch - Low Side Option BE18 CLEAR
Dirty Filter Switch for ERV Wheel Filters
- High Side
Option BE28 with
EW Option
GREEN
Dirty Filter Switch for ERV Wheel Filters
- Low Side
Option BE28 with
EW Option
CLEAR
Factory-installed tubing for pressure sensors is color coded.
8.1 System
Controller
(cont’d)
Senses Option Installation and Function
2 Speed Fan Control
Based on Active Heating
or Cooling Mode
VFC1
Supply airflow is factory set to order specifications but is adjustable
via the unit controller.
Duct Static Pressure
(0 to 2.5" iwc)
VFC3
Requires field installation of sensor in the supply duct. See
instructions below and in the sensor manufacturer's installation
form.
Building Static Pressure
(-0.5 to 0.5" iwc)
VFC4
Field installed sensor to monitor building pressure. Requires field
installation of tubing and sensor. See instructions below and in the
sensor manufacturer's installation form.
Summer/Winter
Adjustable Constant
Volume Control
VFC9
Supply airflow is factory set to order specifications but is adjustable
via the unit controller.
Sensor Options for
Variable Frequency
Drive
Duct pressure sensing (Option VFC3) has a range of 0 to 2.5”. Building pressure sens-
ing (Option VFC4) has a range of -0.5 to +0.5”. Both pressure transducers sense differ-
ential or gauge (static) pressure and convert this pressure difference to a proportional
high level analog output (0-10Vdc) for both unidirectional and bidirectional pressure
ranges. The transducers are designed to be used with air or nonconducting gases. The
operating and compensated temperature limits of the transducers are 0˚F to +150˚F
(-18˚C to +65˚C).
The transducer is mounted in the control compartment. Installation of the tubing and
pickup tubes must be done at the site. The location and position of the sensor pick-
ups is important. Follow the instructions below and the manufacturer’s instructions for
installing pickup tubes and tubing.
Pressure Sensors,
Option VFC3 and VFC4
Unit Control Panel
16
U7
15
Pressure Tranducer
COM
OUT
EXC
Ground
0-10Vdc
24Vdc
1. Tubing Requirements
All tubing is field supplied. The transducer is equipped with 1/4” O.D. pressure
fittings for the pressure signal connection. Both the positive (high) pressure port
and the reference (low) pressure port are located on the front of the transducer,
labeled “HIGH” and “LOW” respectively.
For best results (shortest response times), 3/16” I.D. tubing is suggested for tubing
lengths up to 100 feet (30M), 1/4” I.D. for tubing lengths up to 300 feet (91M), and
3/8” I.D. for tubing lengths up to 900 feet (274M).
Tranducer in the
Control Compartment