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69-2205-03
50027910-001
M27302
M27323
Differential Pressure Switch
INSTALLATION INSTRUCTIONS
APPLICATION
The differential pressure switch senses changes in
duct air pressure to confirm air movement, providing
a safeguard that airflow is present during the
operation of installed IAQ equipment.
M27300
Fig. 1. Pressure switch.
Rubber Grommet
Tubing Fitting Elbow
Tubing, 1/4 in. ID 10 ft
Differential Pressure Switch (Fig. 1) 1
Screws, #8 x 3/4 in. sheet metal 2
Terminal Adaptor 2
SPECIFICATIONS
SPST: normally open, snap-acting contacts
Pressure setpoint contacts: change at 0.04 in. W.C.
Electrical
5 amp resistive @ 24VAC
One common (C), One Normally Open (NO) quick-
connect terminals
Operating Temperature: -40F to 190F (-40C to 88C)
Pressure Sample Taps
Black positive pressure tap. 1/4 in. outside diameter
Grey negative pressure tap. 1/4 in. outside diameter
Use with 1/4 in. inside diameter tubing (10 ft pro-
vided)
Table 1. Parts Included.
Item Quantity
2
2
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50027910-001 DIFFERENTIAL PRESSURE SWITCH
M27301
4-13/64 (107)
3-13/16 (97)
3-15/16
(100)
[2] 1/2 (13)
[2] 1/4 (6)
3/16
(5)
5/64
(2)
Ø3-1/4
(83)
FULL
R
Ø3/16
(5)
27/32
(21)
2-1/64 (51)
1-19/32 (41)
POSITIVE
PRESSURE
PORT
NEGATIVE
PRESSURE
PORT
COMMON (C) TERMINAL
1/4 (6) X 1/32 (1) THICK
QUICK CONNECT
NORMALLY OPEN (NO)
TERMINAL 1/4 (6) X 1/32 (1)
THICK QUICK CONNECT
C
1
2
3
1
2
3
2
3
NC
NO
+
PI
ASSEMBLED
IN MEXICO
M27303
A
B
SUPPLY DUCT INSTALL - AIR LINE ONLY TO TAP A,
CONNECTED TO THE + PORT ON THE AIR FLOW SWITCH
RETURN DUCT INSTALL - AIR LINE ONLY TO TAP B,
CONNECTED TO THE – PORT ON THE AIR FLOW SWITCH
SUPPLY/RETURN DUCT INSTALL - AIR LINE CONNECTED
TO BOTH THE + AND – PORTS ON THE AIR FLOW SWITCH
Fig. 2. Pressure switch dimensions.
Mounting position: mount vertically (upright) with
logo right-side up.
Approvals
Underwriters Laboratories Inc. Approved: MP2168
Canadian Underwriter Laboratories Inc. Approved:
MP2168
M27300
Fig. 3. Pressure switch—oriented vertically.
3. The return duct is recommended, however the
switch can also be mounted to the supply duct.
INSTALLATION
• Read these instructions carefully. Failure to follow
them could damage the product or cause a
hazardous condition. This control must be installed
in accordance with the local code and regulations.
• Check ratings and descriptions given in the
Specifications section to ensure the product is
suitable for your application.
• Installer must be a trained, experienced service
technician.
IMPORTANT
Do not install the switch in an area where temperature exceeds rating of -40F to 190F (-40C
to 88C)
1. Disconnect power from the Humidifier before
installing.
2. Mount the switch vertically with pressure con-
nectors facing down, using provided self-tapping screws to secure the switch to the duct.
IMPORTANT
Calibration accuracy requires that the switch
be mounted vertically (as pictured in Fig. 3).
69-2205—03 2
Fig. 4. Mounting the pressure switch.
4. Cut a 3/4-in. diameter hole in the duct within 10
feet of the switch to ensure the provided tubing
reaches the pressure tap elbow.
5. Insert the grommet into the duct hole, then
insert the tube elbow into the grommet.
6. Connect the tubing to the elbow fitting and the
other end to the applicable pressure connection
on the switch:
a. Black connection if installed on the supply
b. Grey connection if installed on the return
IMPORTANT
With low-speed airflow or variable speed systems it is recommended to run tubing to both
the supply and return ducts.
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Fig. 5. Install tubing.
M27304
INSIDE
OF DUCT
CONNECT TUBING TO + CONNECTION IF PRESSURE TAP IS
MOUNTED TO SUPPLY DUCT. CONNECT TO – IF PRESSURE
TAP IS MOUNTED TO RETURN DUCT.
1
1
L
M37185
HUMIDIPRO
H6062
AIR PROVING
(OR JUMPER)
24VAC
COM
HUM
HUM
AP
AP
Air Proving
Humidistat
1
1
THERMOSTAT OR HUMIDISTAT
AIR PROVING JUMPER COMES
PRE-INSTALLED. REMOVE JUMPER
IF AIR PROVING IS UTILIZED.
HumidiPRO
M35152
POWER IN
G OR W
C
OR
AIR PROVING
DEVICE
HE150/HE250 USES A 15 VA TRANSFORMER WIRED INTO 24V IN.
HE100/HE200 USES A 10 VA TRANSFORMER WIRED INTO 24V IN.
HE300 USES A LINE CORD PLUG.
CONNECT G TO HUMIDIFY WHEN THERE IS A FAN CALL.
CONNECT W TO HUMIDIFY WHEN THERE IS A HEAT CALL.
NEVER CONNECT BOTH. CONNECT C WHEN USING G OR W.
USE AIR PROVING DEVICE INSTEAD OF THE G/W CONNECTION
TO HUMIDIFY ANY TIME THE FAN IS OPERATING.
1
1
2
3
3
2
LEFT
LEFT
OUTDOOR
SENSOR
C
R
U
U
S
S
HVAC
RECOMMENDED
AIR FLOW
SWITCH (AFS)
HVAC
POWER
MASTER
THERMOSTAT
GYWRRc
GYWRC
TrueSTEAM - INTERNAL
24V
24V
HUM
HUM
C
GT
R
RT
GF
EXT
M24756B
NOTE: You may cut the tubing to fit the connection
length between the elbow fitting an d switch. It
is also recommended to secure the hose to
existing structures to avoid accidental disconnection.
WIRING
Fig. 6 shows a close-up of the pressure switch wiring.
This applies to all wiring diagrams (Fig. 9–9).
ATTACH ADAPTER
WIRE TO TrueSTEAM
C TERMINAL
COMMON (C) TERMINA
1
3
IN MEXICO
ASSEMBLED
3
NC
1/4 (6) X 1/32 (1) THICK
QUICK CONNECT
M27398
C
1
2
2
3
ATTAC H
ADAPTOR
2
NO
PI
+
NORMALLY OPEN (NO)
TERMINAL 1/4 (6) X 1/32 (1)
THICK QUICK CONNECT
WIRE TO HVAC
C TERMINAL
Fig. 6. Close-up of pressure switch wiring.
50027910-001 DIFFERENTIAL PRESSURE SWITCH
Fig. 8. Wiring to TrueEASE humidifier
Fig. 7. Wiring to HM750 Electrode humidifier
Fig. 9. Wiring with TrueSteam.
3 69-2205—03
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50027910-001 DIFFERENTIAL PRESSURE SWITCH
Resideo Inc., 1985 Douglas Drive North,
www.resideo.com
This product is manufactured by Resideo Technologies, Inc., Golden Valley, MN, 1-800-633-3991
©2019 Resideo Technologies, Inc. The Honeywell Home trademark is used under license from Honeywell International Inc. All rights reserved.
Golden Valley, MN 55422
69-2205—03 M.S. Rev. 04-19 | Printed in United States
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