Robertshaw 2374-510 Installation and user guide

INSTALLATION DATA
2374-510
UNIVERSAL AIR PRESSURE
SENSING SWITCH
191 E. North Avenue
Carol Stream Illinois 60188 USA
Customer Service Telephone [phone]
Customer Service Facsimile 1.800.426.0804
[email protected]
Invensys™ and Robertshaw® are trademarks of Invensys
plc., its subsidiaries and/or affiliated companies. All
other brands mentioned may be the trademarks of their
respective owners.
www.Uni-Line.com
www.InvensysControls.com
©2011 Invensys Controls
5/11 - LTNS2000008 00
For Technical Service
Telephone [phone]
Facsimile 1.630.260.7294
[email protected]

(1) eld adjustable switch
(1) black set point adjustment screw
(1) hexagon key wrench
(5) color-coded springs
(8) color-coded orices
(1) half strap mounting bracket
(1) angle ("L") bracket
(1) mounting screw for optional brackets
(2) #6 x ⅜" mounting screws for optional brackets

The Robertshaw® 2374-510 Air Pressure Sensing Switch
has a glass-lled polycarbonate housing containing a
sensing diaphragm and an integral snap-acting switch
with three male 90° quick-connect terminals. The switch
can sense positive, negative or differential air pressure.
The eld adjustable set point range of this switch is
0.10" W.C. to 10.0" W.C. Using the switch accessories
contained in this kit, the switch can be applied to a
wide variety of residential and light commercial HVAC
applications.

Calibration requires a manometer (not included in the kit)
as well as the included 7⁄32" hex wrench.
1. Establish the set point as follows. Referring to Table 2 in
this manual, select the appropriate spring for the required
set point range. Insert the spring into the center well of
the mounting pan (light gray side of the switch housing).
2. Insert the black set point adjustment screw, and rotate
it manually until the threads are engaged.
3. Connect the switch to a manometer. Using the 7⁄32"
hex wrench provided in the kit, turn the adjustment screw
in small increments until the desired set point is reached.
Turn the screw clockwise to increase the set point or
counterclockwise to decrease the set point. For precise
calibration, conrm the set point at actual operating
temperature with a manometer. Following precise
calibration, if desired, seal the adjusting screw using a
UV curable adhesive/sealant. 



Using the (2) #6 x ⅜" mounting screws included in the
kit, mount via the integral foot bracket (see Fig. 1) or, via
either of the optional brackets (see Figs 4 & 5) included
in the kit. If using one of the optional brackets, attach it
to the switch with the self-tapping screw provided before
mounting the switch. Select a mounting location free
from vibration. Mount with the diaphragm in any vertical
plane. Avoid mounting with the sample line connections
directed upward.

The snap switch has three ¼" 90° male quick connect
terminals. Before pressure is applied to the diaphragm,
the switch contacts are in the deactivated position as
shown in Figure 2.

Integral sample line connectors, located on both sides
of the diaphragm, accept 3⁄16" ID exible tubing. See
Figure 3. The High or Positive inlet (P1) is black and the
Low or Negative inlet (P2) is gray. Connect the sample
lines as follows:
 Connect the sample line to P1;
P2 remains open to the atmosphere.
 Connect the sample line to P2;
P1 remains open to the atmosphere.
 Connect higher negative sample
to P2; lower sample to P1.
 Connect higher positive sample
to P1; lower sample to P2.
     Connect positive
sample to P1; connect negative sample to P2.

Some applications require a delayed switching action
after set point is reached. The delay is created by
inserting an orice plug into either or both of the sample
line connectors to restrict air ow. Eight orice plugs in
four color-coded sizes are included in the kit as shown
in Table 3. Note that the measuring device and the air
switch must both contain the same size restricting orice in
order to obtain an accurate measurement of the set point.


 Bleed hole in Mounting Pan

 
Black 0.10 thru 0.30
Natural 0.30 thru 0.90
Yellow 0.90 thru 2.50
Red 2.50 thru 5.00
Blue 5.00 thru 10.00

 
Green 0.010
Gray 0.016
Red 0.028
Blue 0.035


This pressure switch may control air ow into the combustion chamber. Improper adjustment of the pressure
switch in the eld, or use of the switch for an application for which it was not intended, may introduce carbon
monoxide into the ventilation system.
 is a dangerous, poisonous gas you cannot see or smell. Symptoms of carbon monoxide
exposure or poisoning include dizziness, headache, nausea, weakness, sleepiness, muscle twitching, vomiting
and inability to think clearly. If you experience these symptoms, 
The pressure switch must be tested thoroughly by an
HVAC professional before the HVAC system is restarted.

• The U.S. Consumer Product Safety Commission warns that carbon monoxide gas is an “invisible killer.”
Carbon monoxide gas is colorless, odorless and deadly.
• Carbon monoxide is produced by burning fuel, including natural gas and propane.
• Proper installation, operation and maintenance of fuel-burning appliances in the home is the most important
factor in reducing carbon monoxide poisoning.
• Be sure that fuel burning appliances, including HVAC systems, are installed by professionals according to
manufacturer's instructions and codes.
• Always follow the manufacturer's directions for safe operation.
• Have the HVAC system (including pressure switches) inspected and serviced annually by a trained service
technician.
• Examine vents regularly for improper connections, visible cracks, rust or stains.
• lnstall battery-operated carbon monoxide alarms. The alarms should be certied to the requirements of
the most recent UL, lAS and CSA standard for carbon monoxide alarms. Test carbon monoxide alarms
regularly and replace dead batteries.
If you have any questions regarding the installation, use or safety of this switch, please call Technical Service at
[phone]. This sensing switch must be installed, adjusted and serviced by a qualied HVAC installation
technician.
Fig. 3. Standard integral connector accepts 3⁄16"
ID tubing.
Fig. 2. Without pressure applied to the diaphragm,
switch contacts are in the position shown.

Fig. 1: Dimensions: NS2 Switch with integral connectors and mounting feet.
Figure 5: "L" Bracket
Figure 4: Half Strap Bracket




Body Glass-lled polycarbonate
Diaphragm Silicone
Terminals Copper alloy
Contacts Fine silver

Operating Range 0.10 ″ W.C to 10.0″ W.C.
Max. Pressure Rating 14″ W.C.
Mounting Standard: Diaphragm vertical
Operating Temperature -40 to +88 °C (-40 to +190 °F)
Sample Line Connections Black: positive
Gray: negative
Sample Medium
Air and byproducts of combustion
that will not degrade silicone or
polycarbonate
Product Life 100,000 cycles minimum

Electrical
Rating
Standard Silver Contacts
SPDT Electrical load
1⁄10 HP @120 to 277 VAC
28 VA pilot duty @ 24 VAC
125 VA pilot duty @ 120 VAC
SPST Electrical load
5 Amps resistive @ 24, 120 to 277 VAC
Contact Arrangement SPDT
Electrical
Connectors
quick-connect
terminals ¼″ x 0.032

Approvals UL, CUL, CSA, CE,
Australian Gas Association
Accessories Consult Factory
Are you reading a FAX or a COPY of this bulletin? DOWNLOAD the full-color PDF version of this and other
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Are you reading a FAX or a COPY of this bulletin? DOWNLOAD the full-color PDF version of this and other
literature at our website! http://www.invensyscontrols.com


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• Select Air Pressure Sensing Switches
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change with an operating range of -40 °F
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