Manual 2100-620A - Bard D36A2P/BLD.10304 Installation And Service Instructions Manual

- Unit 1 Damper Fail to Close
- Unit 1 Filter Maintenance Alarm
Should Unit 1 encounter any of these issues, they will
be communicated to the LC board which will energize
the HVAC 1 fail relay with -24VDC, opening terminals
29 and 30. Additionally, the board will enable remote
alarms.
Board Relays and Alarm Schemes
There are two alarms handled without the use of
external isolation relays. They are board-initiated relays.
• HVAC 2 Fail: The HVAC 2 fail relay will be
energized from the LC board through any of the
following situations:
- Unit 2 Loss of Power
- Unit 2 Dirty Filter Switch
DC-FREE COOLING UNIT OPERATIONAL PARAMETERS
Overview
The Bard DC-Free Cooling Unit system is pre-programmed to provide the most efficient operating parameters based
on indoor temperature, outdoor temperature, dewpoint and relative humidity. The following operational parameters
are factory default.
Cool Weather Operation (Free Cooling Available):
Stage 1 Cooling 78°F – Lead unit free-cooling damper opens (Setpoint + Cooling Stage 1 Differential)
Stage 2 Cooling 79°F – Lag unit free-cooling damper opens (+ Cooling Stage 2 Differential)
Stage 3 Cooling 81°F – Lead unit compressor, damper will stay open if conditions are conducive for free cooling
(+ Cooling Stage 3 Differential)
Stage 4 Cooling 83°F – Lag unit compressor, damper will stay open if conditions are conducive for free cooling
(+ Cooling Stage 4 Differential)
Hi-Temp Alarm #1 85°F
Hi-Temp Alarm #2 90°F – Emergency ventilation initiates, both dampers open, both blowers run
75°F – All cooling stops, blowers stop (Setpoint -2°F)
Stage 1 Heating 58°F – Lead unit heat strip activates
Stage 2 Heating 56°F – Lag unit heat strip activates
Low-Temp Alarm 45°F
62°F – All heating stops, blowers stop
Warm Weather Operation (No Free Cooling Available):
Stage 1 Cooling 78°F – Lead unit compressor (Setpoint + Cooling Stage 1 Differential)
Stage 2 Cooling 83°F – Lag unit compressor (+ Cooling Stage 2, Stage 3 and Stage 4 Differentials)
Hi-Temp Alarm #1 85°F
Hi-Temp Alarm #2 90°F – Emergency ventilation initiates, both dampers open, both blowers run
75°F – All cooling stops, blowers stop (Setpoint -2°F)
- Unit 2 High/Low Pressure Switches
- Unit 2 SAT/OAT/RAT/OAH Sensor Fail
- Unit 2 Loss of Communication
- Unit 2 Damper Fail to Open/Close
- Unit 2 Damper Fail to Close
- Unit 2 Filter Maintenance Alarm
Should Unit 2 encounter any of these issues, they will
be communicated to the LC board, which will enable
remote alarms and also open terminals 31 and 32.
• Lag Unit Run: Should temperature rise within the
shelter require both compressors to run concur-
rently, the LC board will enable remote alarms and
open terminals 23 and 24.

Manual 2100-620A

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