WattMaster VAVBOX - Manual (Page 5)

VAVBOX Controller
Technical Guide
5
General
The following inputs and outputs are available on the VAVBOX con-
troller and the OE322 Output Expansion Board that can be added by
connecting it to the main controller board expansion port. For compo-
nent locations of the inputs on the VAVBOX Controller see Figure 3.
For wiring of inputs and outputs see Figure 4 thru 9.
VAVBOX Controller Analog Inputs:
Input #1: Space Temperature Sensor
The Room Sensor that reads space temperature is attached the TMP and
GND terminals. If the Room Sensor with slide adjust option is used a
third wire connects to terminal AUX1.
Input #2: Airflow Sensor
If the VAVBOX Controller is to be configured for pressure independent
operation, you need to install the OE274 Airflow Sensor and connect
the modular plug from the pressure sensor to this input. The pressure
signal from the Airflow Sensor is used for CFM (airflow) calculations.
If an OE274 Airflow Sensor is attached to this input, the VAVBOX
controller will automatically detect this and switch to pressure indepen-
dent operation. If the sensor is not attached or becomes defective, the
controller automatically reverts to pressure dependent operation.
Input #3: Supply Air Temperature Sensor
The optional Supply Air Temperature Sensor is connected to terminals
AUX2 and GND when it is used. If it is to be used as a Supply Air
Sensor , it should be mounted in the supply duct close to the terminal
unit where the VAVBOX controller is installed. This sensor can be used
for monitoring purposes or in place of the Supply Air Temperature Broad-
cast from the WMVAV Controller.
Note: All temperature sensors must be Thermistor Type III.
Other Controller Connections
Expansion Board Modular Connector
This modular connector is used to connect the optional OE322 Output
Expansion Board to the VAVBOX controller. These boards are only
required when electric or hot water heating and/or fan terminal control
is required. The expansion boards are not required for cooling only
terminal units.
Actuator Modular Connector
This modular connector is used to connect a modular cable from the
VAVBOX controller to a tri-state actuator.
Optional - OE322 Expansion Board
As previously stated when control of a fan or if heating is required the
OE322 Output Expansion board must be used.
Relay Output #1 - Fan Enable
The first expansion relay on the Output Expansion boards is used for
enabling the fan for Series or Parallel Fan Terminal Units.
Relay Output #2 - Stage 1 Heating
If you have at least one stage of auxiliary heating, this is the relay used
to energize the 1st stage of terminal unit heating. This heating stage can
either be used with electric heat or On/Off hot water valve control.
Relay Output #3 - Stage 2 Heating
If you have two stages of auxiliary heating, this relay controls the 2nd
stage of electric heat. For 3 stage heating, this relay output would be
energized for both the 2nd and 3rd stage of heat. See the following
section for more information regarding 3 stage heating applications.
3 Stage Heating Applications
If three stages of electric heat are configured, relays #2 and #3 will
stage in a staggered sequence. This allows you to achieve 3 stages of
heating using only relays #2 and #3. Each of the 3 heating elements
should be sized for 1/3 of the total KW output required. Both the 2nd
and 3rd stage heating contactors (C2 & C3) must be connected to Relay
Output #3. See Table 1 for relay sequencing information.
Stage No. Relay Output #2 Relay Output #3
#1 ON (C1) OFF (C2 & C3)
#2 OFF (C1) ON (C2 & C3)
#3 ON (C1) ON (C2 & C3)
Table 1: Relay Sequencing For 3 Stage Heating
24 VDC Power Terminals (+V & GND)
These terminals can supply 24 Volts DC for a 24 VDC hot water valve
actuator if desired. This output is rated at 12 Watts maximum load.
Analog Output
If you are using hot water or steam heating via a modulating steam or
hot water valve, this output can supply a 0-10 Volts DC signal for pro-
portional control of the valve.
Controller Inputs and Outputs