ACI-Automation Components BACnet IMMERSION SERIES Installation Instructions

BACnet IMMERSION SERIES

Installation & Operation Instructions

GENERAL INFORMATION

The BACnet Immersion Series sensor is designed for use

with electronic controllers in commercial heating and

cooling building management systems. The ACI BACnet

Immersion Series sensor can be ordered to monitor

temperature in commercial HVAC pipes. It uses BACnet

MS/TP for physical connection to a BAS or controller, has

dip switches to set addresses and baud rate, and has on

board end-of-line termination. There is no analog output.

WIRING INSTRUCTIONS

The BACnet Immersion Series temperature sensor has a
depluggable terminal block located on the front of the
PCB. For ease of wiring, we recommend removing the
block, wiring, and reattaching before mounting. 16 to
22 AWG two conductor shielded cable is
recommended for powering the sensors.

ACI recommends using Belden 3105 or compatible cable for
RS-485 communication wiring. This wire has 120 ohm input
impendence. The terminal blocks allow for (1) or (2) wires to
be connected in each position for daisy chaining. Daisy
chain the RS-485 wiring and do not use “Star” or “T” wiring.

FIGURE 1: ENCLOSURE DIMENSIONS

3.60"

(91.44 mm)

4.79"

(121.55 mm)

2.25"

(57.15 mm)

2.35"

(59.80 mm)

FIGURE 2: LAYOUT

TERMINAL BLOCKS

V D-GN

POWER

D+

BACNET

LED

END OF LINE
TERMINATION

EN DIS

Avoid running communication wires next to AC line
voltage wires. These can be sources of noise that can
aect signal quality.

PRECAUTIONS

• DO NOT RUN THE WIRING IN ANY CONDUIT WITH

LINE VOLTAGE (24/120/230 VAC).

Remove power before wiring. Never connect or

•

disconnect wiring with power applied.

It is recommended you use an isolated UL-listed

•

class 2 transformer when powering the unit with
24 VAC. Failure to wire the devices with the correct
polarity when sharing transformers may result in
damage to any device powered by the shared
transformer.

23618421421

4
6

ADDRESS BAUD

RESET BUTTON

TABLE 1: WIRING CONNECTIONS

TERMINAL

BLOCKS

+V

GN

D-

D+

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CONNECTIONS

Power Supply Positive 12-36 VDC / 24 VAC

Power Supply Common or Ground

EIA-485 Data Negative

EIA-485 Data Positive

DIP SWITCH

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PRECAUTIONS

If the 24 VDC or 24VAC power is shared with devices

•

(Continued)

that have coils such as relays, solenoids, or other
inductors, each coil must have an MOV, DC/AC Transorb,
Transient Voltage Suppressor (ACI Part: 142583), or
diode placed across the coil or inductor. The cathode, or
banded side of the DC Transorb or diode, connects to
the positive side of the power supply. Without these
snubbers, coils produce very large voltage spikes when
de-energizing that can cause malfunction or
destruction of electronic circuits.

For optimal temperature readings, follow these tips:

• The sensor thermowell should be installed against the ow

of the water, where water temperature is well mixed (no
stratication).

*Reference FIGURE 4 (next page)

• Make sure the entire thermowell is immersed. If the

thermowell is longer than the pipe diameter, the
thermowell should be installed in an elbow or Tee.

• Apply thermal grease to the end of the probe before

installation into thermowell (ACI Item #102595).

• The tip of the thermowell should be located in the

middle of the pipe.

FIGURE 4: ASSEMBLY

IMMERSION SENSOR

THERMOWELL

PIPE INSULATION

THREADOLET

PIPE WALL

MOUNTING

TABLE 2: PROBE & INSERTION LENGTH

ACI PART #

A/BN1110-INW2.5-PB

A/BN1110-INW4-PB

A/BN1110-INW6-PB

IMMERSION LENGTH

2.5” (63.50 mm)

4.0“ (101.60 mm)

6.25” (158.75 mm)

PROBE LENGTH

4.31” (109.47 mm) +/- 0.13” (3.30 mm)

5.81“ (147.57 mm) +/- 0.13” (3.30 mm)

7.81” (198.37 mm) +/- 0.13” (3.30 mm)

FIGURE 3: PROBE and IMMERSION

½” NPSM
Instrument Thread

Instrument Thread

½” NPSM

(25.40 mm)

REFER TO Probe Length Table

1.00”

0.78”
(25.40 mm)

½” NPT
Instrument Thread

REFER TO Immersion

Insertion Length Table

FIGURE 5: TEE MOUNT ASSEMBLY

IMMERSION SENSOR

THERMOWELL

ADAPTER

TEE PIPE FITTING

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THERMOWELL INSTALLATION

ACI’s standard Immersion sensors are made to install into a

½” NPT female thread. Typically a Threadolet or Tee is

installed into the pipe, but a hole can also be drilled and

tapped. The pipe/system will need to be drained, unless a

Hot Tap is being used. The recommend drill size is 23/32 in.

(18 mm). Drill the hole, and tap the hole with ½”-14NPT.

Always use proper thread sealants on tapered pipe
threads of the thermowell. Screw the thermowell into the
Threadolet, Tee, or tapped hole, using a wrench to tighten
it rmly. Rell the system and check for leaks.

FIGURE 6: THREADOLET ASSEMBLY

THREADOLET

THERMOWELL

TIP OF THERMOWELL
IN MIDDLE OF PIPE

PIPE INSULATION

Best practice is to apply thermal grease to the end of the
probe, but not required. Insert and push the sensor probe
into the thermowell. Turn the sensor probe assembly
clockwise to tighten down completely.

Open the cover of the enclosure. Refer to the wiring
instructions (p. 3) to make necessary connections. After
wiring, attach the cover to the enclosure.

PROBE INSERTION

The “-INW” includes a standard ½” NPS process thread to
be used with a machined thermowell or previously
installed thermowell. Verify the existing thermowell
insertion length of the pipe is suitable for your selected
Immersion.

If the length of the probe is too large, the probe may be
pressed into its enclosure - up to an inch of clearance.

Note: *Fabricated (welded) thermowells (-I) are not
intended for moving water or high pressure service. Fluid
velocity and wake frequency are primary factors in well
failure. Machined thermowells (-IM) should be used in
these types of applications. Fabricated thermowells are
intended for tank, or low to no ow, applications.

PIPE WALL

FIGURE 7: ELBOW ASSEMBLY

FLOW DIRECTION

BACnet MS/TP INTERFACE

The BACnet Master-Slave/Token-Passing (MS/TP) data link protocol uses EIA-485 as a two-wire, daisy chain network. A branch is
a discrete chain of devices connected to a controller. The max number of devices per segment is (32), as per the BACnet
specications. 4000 ft (1219.2 m) is the maximum recommended length for a segment, which includes all devices from the
controller to the last device in the daisy chain. ACI’s BACnet sensors are master devices. Only master nodes are allowed to send
and receive tokens on the MSTP network.

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