iWorx® VPU2
32
505-010-2, Effective: April 29, 2014
© 2014 Taco Electronic Solutions, Inc.
• Local Alarm (VAVI shutdown)
• Occupancy Mode: occupied, unoccupied, and occupied extension)
• Supplemental heat status: on, off
Associating VAVIs
In order for the VPU2 and VAVIs to share information the controllers need to be associated. To associate the VAVIs to
the VPU2 you first need to select the VPU2 from the LCI's list of controllers. Once the VPU2 has been selected
depress the HVAC Setup button then the Zone Members button. There is a list of all VAVIs on the network that will be
displayed along with the designation “Included” or “Excluded.” To include a VAVI, simply depress the desired VAVI in
the list and it will show “Included” and the color will change to Red. After all the desired associations are complete
depress the
Save
button so the information will be sent to all associated controllers.
Associating the Reference Zone; VAVI
In order for the VPU2 and reference VAVI to share information the controllers need to be associated. To associate the
reference VAVI to the VPU2 you first need to select the VPU2 from the LCI's list of controllers. Once the VPU2 has
been selected depress the HVAC Setup button then the Reference Zone button. There you will see a list of all VAVIs on
the network along with the designation “Included” or “Excluded” for each. To include the reference VAVI, simply
depress the desired VAVI in the list and it will show “Included” and the color will change to Red. After all the desired
associations are complete, depress the
Save
button so the information will be sent to all associated controllers. The
VPU2 may have only one (1) reference zone.
Power On/Reset Delay
The VPU2 imposes a thirty second delay after being powered on or after a reset. No control takes place until after the
thirty second delay has expired.
Supply Air Temperature Monitoring
The VPU2 monitors the supply air temperature to determine if the heating and cooling stages are operating properly.
During heating mode, if the supply air temperature does not rise above the heat mode alarm setpoint after a 10-minute
delay a heat mode alarm is generated. During cooling mode, if the supply air temperature does not drop below the cool
mode alarm setpoint after a 10-minute delay, a cool mode alarm is generated.
The VPU2 has provisions for detecting a gas valve that has been become stuck in the open position. The stuck gas
valve sequence helps to prevent overheating the HVAC unit.
During periods when the operational mode is primary off or primary fan only, if the supply air temperature rises above
175
°F the system fan is started. If the supply air temperature does not drop below 150
°F after 5 minutes, the fan
speed decreases to 0% and an alarm is sent to the zone controllers and LCI. The zone controllers react to the alarm by
positioning their dampers to the maximum position.
During periods when the operational mode is primary cooling, if the supply air temperature does not drop below 100
°F
after 15 minutes, the cooling mode is terminated and the controller enters the primary off operational mode. The pri-
mary off logic then checks for the stuck gas valve condition.
Smoke Detection
A smoke detector input is provided. If the smoke detector indicates smoke is present then all of the stages and the fan
turn off. Once the situation has been corrected, reset the controller to clear this condition.
Mixed Air Low Limit Detection
An input is provided for a mixed air low limit detection device. If a low limit condition is detected, all of the stages and
the fan turn off. Once the low limit is corrected, reset the controller to clear this condition.
