Honeywell W7751D, W7751B, W7751F Installation instruction

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The Excel 10 VAV Controller is a Free Topology Transceiver
(FTT) LonMark compliant device that is available in three
versions: See Fig. 1.

1. W7751B—OEM Snaptrack-Mount, reference part
number 207912. Use a 3-1/4 inch by 9 inch (82 mm by
228 mm) section for each installation.

2. W7751D—Internally Wired Subbase mounts on a
standard four by four, a standard five by five conduit
box or on DIN Rail 1-3/8 by 9/32 (35 mm by 7.5 mm)
EN 50 022.

3. W7751F—Externally Wired Subbase, can be mounted
in a ring cabinet or on DIN Rail 1-3/8 by 9/32 (35 mm
by 7.5 mm) EN 50 022.

The models all contain a Microbridge air flow sensor and
communicate via the 78 Kilobaud Echelon LonWorks
E-Bus Network. They differ only in mounting and
terminations.

Any hardware that will be driven by the Triac outputs must
have a minimum current draw, when energized, of 25 mA at
20 Vac, a maximum of 500 mA at 30 Vac for the W7751B
and 1 A at 30 Vac for the W7751D,F.

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Mount the VAV controllers in locations that allow clearance
for wiring, servicing and module removal. (See Fig. 3 and 4
for mounting options used with the W7751D,F Subbase and
Fig. 5 for mounting dimensions.)

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The W7751B OEM model is implemented on a snaptrack
compatible printed wiring board (PWB). Terminal blocks are
used to make connections to the digital input terminals (13
through 17) the wall module terminals (19 through 25), and
the communications terminals 29 and 30. Connection for to
access the E-Bus is provided by plugging the connector into
the communications jack. Digital outputs, earth ground and
24 Vac power connections are made with quarter inch
(6.35 mm) quick connects.

Mount the VAV controller onto the snaptrack. Attach all
wiring to the appropriate quarter inch (6.35 mm) quick
connects and terminal blocks. See Wiring section.

3-1/4 IN. (82 MM)
SNAPTRACK

W7751B

U.S. Registered Trademark
Copyright  1997 Honeywell Inc. • All Rights Reserved

P1

P2

+

∆P

–

W7751D W7751F

M12605

95-7504

EXCEL 10 W7751B,D,F VAV CONTROLLERS

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The W7751D uses a two-piece construction controller
module and an internally wired subbase. Remove the
controller module from the subbase (see Fig. 2). Field wiring
14 to 22 AWG (2.0 to 0.34 mm
into the four by four or five by five conduit box and is
connected to the terminal blocks on the subbase. When
wiring is complete, the controller module activates by
plugging into the subbase.

The internally wired subbase either mounts on a standard
4 inch by 4 inch electrical junction box or a standard 5 inch
by 5 inch electrical junction box using No. 6 (3.5 mm)
screws. See Fig. 3. Attach all wiring to the appropriate
terminal blocks on the subbase. See Wiring section. After
checking out all wiring, plug the controller module into the
subbase. Wiring checkout and troubleshooting can also be
performed with the controller module installed, by placing a
probe through the slots in the subbase.

2

) comes through a conduit

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The W7751F uses a two-piece construction controller
module and an externally wired subbase. Remove the
controller module from the subbase (see Fig. 2). This
subbase either mounts into a panel with screws or snaps
onto standard EN 50 022 DIN rail 35 mm by 7.5 mm
(1-3/8 in. by 5/16 in.). See Fig. 4. DIN rail is available through
local suppliers. Mount the subbase to the appropriate
surface. Type of screws (sheet metal, self-tapping or thread
forming) and length is determined by the type of mounting
material at the job site. Field wiring 14 to 22 AWG (2.0 to

0.34 mm
bottom external edges of the subbase. When wiring is
complete, the controller module activates by plugging into
the subbase.

Attach all wiring to the appropriate terminal blocks on the
externally wired subbase. See Wiring section. After checking
out all wiring, plug the controller module into the subbase.

2

) is connected to the terminal blocks on the top and

M8359

Fig. 2. W7751D,F controller module removal/replacement

(W7751D shown).

NO. 6 (3.5 MM) SCREW (4)

M8360

Fig. 3. W7751D Subbase four by four or five by five
conduit box mounting options (proper orientation is
vertical with terminals at top and bottom as shown).

NO. 6 (3.5 MM)
SCREW (4)

DIN RAIL RELEASES

DIN RAIL

M12602

95-7504 2

Fig. 4. W7751F Subbase wall and DIN rail mounting

options (proper orientation is vertical with terminals at

top and bottom as shown).

MAINTAIN A MINIMUM DISTANCE
OF 4 IN. (100 mm) FROM OTHER
DEVICES OR PANELS FOR
ATTACHING AIR FLOW TUBING.

5-21/32

(144)

1-3/8

(35)

DIN RAIL

MOUNTING

SLOT

EXCEL 10 W7751B,D,F VAV CONTROLLERS

3/4

(19)

3-7/16

5 X 5

MOUNTING

HOLES

1-3/32

(28)

4 X 4

MOUNTING

HOLES

(87)

5-21/32 (144)

MAINTAIN A MINIMUM DISTANCE
OF 3 IN. (76 mm) FROM OTHER
DEVICES OR PANELS FOR ACCESS
TO THE COMMUNICATIONS JACK.

2-11/32 (60)

Fig. 5. W7751D,F Subbase mounting dimensions (W7751D shown).

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Connect the air flow pickup to the two connectors on the VAV
controller. See Fig. 6.

NOTES:
— Use 1/4 inch (6 mm) outside diameter with 0.040 in.

(1 mm) wall thickness plenum rated 1219 FR (94V-2)
tubing.

— Always use a fresh cut on the end of the tubing that

connects to the air flow pickups and the connectors on the
VAV controllers.

Connect the high pressure or upstream tube to the plastic
restrictor labeled (+) or P1 and the low pressure or
downstream tube to the restrictor labeled (-) or P2. See
labeling in Fig. 6.

NOTE: If controllers are mounted in unusually dusty or dirty

When twin tubing is used from the pickup, split the pickup
tubing a short length to accommodate the connections.

NOTES:

environments, a 5-micron disposable air filter is
recommended for the high pressure line (marked
as +) connected to the air flow pickup. This applies
to all controller models.

— The tubing from the air flow pickup to the VAV

controller should not exceed three feet
(0.914m). Any length greater than this will
degrade the flow sensing accuracy.

— Use caution when removing tubing from a VAV

connector. Always pull straight away from the
connector; never remove by pulling at an angle.

1-1/2

(38)

1/2

(13)

4-21/32 (118)

1-3/32

(28)

M12603

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All wiring must comply with applicable electrical codes and
ordinances or as specified on installation wiring diagrams.

NOTES:
— For multiple controllers operating from a single

transformer, the same side of the transformer secondary
must be connected to the same input terminal in each
controller and the ground terminals (28 on the W7751B,
and 32 on the W7751D,F) must be connected to a verified
earth ground for each controller in the group. See Fig. 7.
(Controller configurations will not necessarily be limited to
three devices, but the total power draw including
accessories can not exceed 100 VA when powered by the
same transformer (U.S. only). See System Engineering
form, 74-2949, for power wiring recommendations.)

— The following pairs of terminals are electrically equivalent

for 24 Vac power wiring:
W7751D,F terminals 1 and 3, 2 and 4.

— All loads on an Excel 10 controller must be powered by

the same transformer that powers the Excel 10 controller.

— Keep the earth ground connection (terminal 28 on the

W7751B, and terminal 32 on the W7751D,F) wire run as
short as possible. Refer to Fig. 11 and 17.

not

— Do

connect the Analog ground nor Digital ground
terminals (13, 16, 22 and 24 on the W7751B and 13, 18,
26, 28 and 31 on the W7751D,F) to earth ground. Refer to
Fig. 11 and 17.

3 95-7504

EXCEL 10 W7751B,D,F VAV CONTROLLERS

AIR FLOW
PICKUP

P2

P1

HI

LOW

M12604

W7751B

AIR FLOW

PICKUP

W7751D,F

Fig. 6. VAV air flow pickup connections.

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The 24 Vac power from an energy limited Class II Power
Source must be provided to each VAV controller. To conform
to Class II restrictions, transformers must not be larger than
100 VA (U.S. only). A transformer that meets CE mark
requirements and that meets the Low Voltage Directive
(LVD) requirements must be used in Europe for all
installations of this product.

IMPORTANT

Power must be off prior to connecting to or
removing connections from terminals 9 and 10 on
the W7751B and terminals 1 and 2 or 3 and 4 on
the W7751D,F.

Use the heaviest gauge wire available, up to 14 AWG
(2.0 mm

2

) with a minimum of 18 AWG (1.0 mm2) for all
power and earth ground wiring. For nonplenum, open areas,
run cables exposed (or in conduit if required).

See the following

IMPORTANT

Equipment (UL 1995, U.S. only)

Heating and Cooling

on

.

IMPORTANT

If the W7750 Controller is used on

Cooling Equipment (UL 1995, U.S. only)

Heating and

and the
transformer primary power is more than 150 volts,
connect the transformer secondary to earth ground,
see Fig. 7.

NOTES:

— Unswitched 24 Vac power wiring can be run in

the same conduit as the E-Bus cable.

— Maintain a three-inch (76 mm) separation

between Triac outputs and E-Bus wiring
throughout installation.

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Refer to
complete description of E-Bus network topology rules.
Approved cable types for E-Bus communications wiring are
Level IV 22 AWG (0.34 mm
unshielded, twisted pair, solid conductor wire. For
nonplenum areas, U.S. part AK3781 (one pair) or U.S. part
AK3782 (two pair) can be used. In plenum areas, U.S. part

E-Bus Wiring Guidelines form, 74-2865

2

) plenum or non-plenum rated

, for a

AK3791 (one pair) or U.S. part AK3792 (two pair) can be
used. Communications wiring can be run in a conduit, if
needed, with

non-switched

24 Vac or sensor wiring. If a
longer E-Bus network is required, a Q7740A 2-way or
Q7740B 4-way repeater can be added to extend the length of
the E-Bus. A Q7751A Router can be added to partition the
system into two segments and effectively double the length
of the E-Bus. Only one router is allowed with each Excel 10
Zone Manager, and each network segment can have a
maximum of one repeater.

Pull the cable to each controller on the E-Bus and connect to
communication terminals 29 and 30 (W7751B), 19 and 20
(W7751D,F).

EARTH
GROUND

EARTH
GROUND

28

9

24V

10

W7751B

COM

M12606

EARTH
GROUND

W7751D,F

32

24V

COM

24V

COM

1234

24 VAC

120/240 VAC

IF THE W7751 CONTROLLER IS USED IN UL 1995 EQUIPMENT

1

AND THE PRIMARY POWER IS MORE THAN 150 VOLTS,
GROUND ONE SIDE OF TRANSFORMER SECONDARY.

EARTH
GROUND

1

TRANSFORMER

32

24V

COM

234

W7751D,F

24V

COM

1

Fig. 7. Power wiring for multiple controllers.

Notes on Communications Wiring:

• All field wiring must conform to local codes and

ordinances (or as specified on the installation drawings).

• Approved cable types for E-Bus communications wiring

are Level IV 22 AWG (0.34 mm

2

) plenum or non-plenum
rated unshielded, twisted pair, solid conductor wire. For
nonplenum areas, U.S. part AK3781 (one pair) or U.S.
part AK3782 (two pair) can be used. In plenum areas,
U.S. part AK3791 (one pair) or U.S. part AK3792 (two
pair) can be used. See Table 11 for part numbers in
System Engineering form, 74-2949.

• Unswitched 24 Vac power wiring can be run in the same
conduit as the E-Bus cable.

• Do not bundle output wires with sensor, digital input or
communications E-Bus wires.

• Do not use different wire types or gauges on the same
E-Bus segment. The step change in line impedance
characteristics would cause unpredictable reflections on
the E-Bus. When using different types is unavoidable, use
a Q7751A Router at the junction.

• In noisy (high EMI) environments, avoid wire runs parallel
to noisy power cables, motor control centers, or lines
containing lighting dimmer switches, and keep at least
3 in. (76 mm) of separation between noisy lines and the
E-Bus cable.

• Make sure that neither of the E-Bus wires is grounded.

95-7504 4