SECTION 23 0x xx – Factory Assembled AHUs
This is supplemental language for an AHU spec. This is not an all inclusive spec. This is language
that is meant to be copied and pasted into an existing AHU spec.
PART 1 - GENERAL
PART 2 - PRODUCTS
A.
CONTROLS
1.
SYSTEM DESCRIPTION
a.
The operating controls for the AHU sequence shall be furnished by the BAS
contractor and factory installed and wired by the AHU manufacturer. The AHU
manufacturer shall still provide controls that are not called to be furnished by the
BAS contractor.
2.
WORK INCLUDED
a.
The AHU manufacturer shall coordinate with the BAS contractor for accepting and
installing the controls. Coordination shall include scheduling, reviewing wiring
diagrams, and coordinating sizing and installation methods.
3.
SUBMITTALS
a.
Include controls data sheets for product furnished by the BAS contractor.
b.
Provide a controls installation wiring diagram. Have the wiring diagram reviewed
by the BAS contractor during submittal phase. The BAS contractor shall sign-off
on the final wiring diagram before the unit is released for production.
4.
EXECUTION
a.
Package air handling unit controls shall be installed in the factory. BAS
Contractor shall coordinate with AHU manufacture for proper controls installation
and wiring requirements.
b.
The BAS contractor shall furnish the following controls for factory installation:
1)
DDC controller – BACnet B-BC level
2)
DDC controller power supply (120/24 with circuit protection)
3)
Input/output modules
4)
Communication ports
5)
Sensors for the operating sequence or to meet the BAS points list, including
temperature, humidity, pressure, airflow, current.
6)
Damper actuators and linkages
7)
Coil control valves and valve actuators
8)
Pilot relays
9)
Freezestats
10) High and low pressure switches
11) Filter switch
c.
The AHU manufacturer shall furnish the following controls and related devices:
1)
Controls not listed above but are required for the operation of the unit
2)
Enclosure for controls with separation between high, line, and low voltage
3)
Starters and contactors
4)
VFDs
5)
Power conditioning controls
Project Name
Date
23xxxx - 1
AHU
5.
6.
B.
6)
Refrigeration controls and safeties
7)
Smoke detectors
d.
All accessible controls wiring mounted inside AHU shall be protected in plastic
flexible conduit. All inaccessible controls wiring, not exposed to weather, shall be
protected in EMT conduit. All controls wiring exposed to weather shall being in
galvanized pipe with watertight fittings.
e.
All wiring shall be in accordance with the Local Electrical Code and the National
Electrical Code. The electrical subcontractor shall be a licensed union electrical
contractor.
f.
The AHU manufacturer shall make provisions for a path for a network connection
to reach the DDC controller from the exterior of the unit. Run an empty conduit
from an accessible location on the exterior of the unit to a dedicated opening in the
DDC enclosure.
g.
The AHU manufacturer shall make provisions for a low voltage wiring path to
reach the DDC controller from the exterior of the unit. Run an empty conduit from
an accessible location on the exterior of the unit to a dedicated opening in the DDC
enclosure.
CONTROLS TESTING
a.
The AHU manufacturer shall test the following at the factory:
1)
Controls safeties
a)
Freezestats shall cut power to dampers and stop supply fan
b)
High and low pressure switches shall stop fans
c)
Smoke detectors shall stop fans
2)
Test the continuity of the wiring to the sensors
3)
Test the power to the damper and valve actuators and test continuity of the
signal wiring
4)
Test that the control pilot relays start/stop the equipment they are wired to.
5)
Test power to the DDC controller
b.
The AHU manufacturer shall test the operation of the controls that they furnished,
such as refrigeration controls, VFDs, starters, etc.
c.
Testing of the operational sequences of operation shall be conducted by the BAS
Contractor in the field.
SHIPPING
a.
The DDC controller shall be packaged to prevent damage during shipping. If the
DDC controller is mounted on a DIN rail, or if the electronic board is susceptible
to vibration damage, then the AHU manufacturer shall remove the DDC controller
from the enclosure and package it so that it is protected during shipping.
b.
The BAS contractor shall re-mount the DDC controller in the field.
Warranty
1.
The BAS Contractor shall warranty the controls that they furnished and the programming
of the sequence of operations.
2.
The AHU Manufacturer shall warrant the controls that they furnished, the installation of
the controls and the wiring and connections.
Project Name
Date
23xxxx - 2
AHU