Cleveland Controls
Division of UniControl Inc.
number of turns is 4, covering the set point
range of 1.0 to 4.0" w.c. Do not exceed
the maximum number of turns. Each full
turn represents approximately 0.75" w.c.
Determine the number of turns required to
approximately position the adjusting screw
as follows:
(REQUIRED SET POINT – INITIAL SET POINT @ 1.0)
0.75
= NUMBER OF TURNS CLOCKWISE
EXAMPLE:
REQUIRED SET POINT = 2.5" w.c.
INITIAL (FACTORY) SET POINT = 1.0" w.c.
(2.5 – 1.0) / 0.75 = 2 TURNS
Please note:
(1) Use a digital manometer and multi meter
(such as the Cleveland Controls Series
6650 Digital Manometer) to achieve pre-
cise set point calibration. Have the RSS-498
switch as close to actual operating tem-
perature as possible during the calibration.
The Cleveland Controls Series PVG-1
Pressure/Vacuum Generator provides a
handy air source for calibration.
(2) Warning: Never place an air pressure
sensing switch into operation without
conrming the set point rst. An incor-
rect setting could result in a hazardous
condition.
APPLICATION
The Series RSS-498-013 Sensing Switch
Kit provides an economical and convenient
solution for many residential and light com-
mercial HVAC applications. The kit contains
a compact Series RSS-498 switch with an
adjustable set point range of 1.0" w.c. to 4.0"
w.c. The switch has been factory set to actu-
ate on a pressure rise of 1.0" w.c. The switch
has a bleed hole (.016") in the mounting pan.
The individually boxed kit includes a P/N
28419 hex wrench (1⁄16") for eld calibration,
a P/N 28429 tube-to-tube reduction adapter,
and two (2) P/N 27577-037 slotted hex head
mounting screws (#6 x ⅜").
GENERAL DESCRIPTION &
OPERATION
The RSS-498 switch has a thermoplastic
housing containing a diaphragm and snap-
acting switch. Duo-barbed sample line
connectors on each side of the diaphragm
accept ¼" ID or 3⁄8" ID slip-on exible tubing.
The .016" bleed hole in the mounting pan
(low pressure side) prevents the build up of
condensation in the switch and sample line.
The electrical connection consists of three
(3) male 90º quick-connect terminals. The
snap action switch can be actuated by a
positive or negative pressure, or by a pres-
sure differential.
MOUNTING (FIGURE 1)
Select a mounting location that is free from
vibration. Mount with the diaphragm in
any vertical plane in order to maintain the
specied operating set point. Do not mount
with the sample line connections directed
upward. Surface mount via the two 0.14"
slots in the integral foot bracket, using the
two (2) slotted hex head mounting screws
(#6 x ⅜") provided in the kit.
AIR SAMPLING CONNECTION
(FIGURE 2)
Refer to Figure 2 to identify the High inlet
(H) and the Low inlet (L). Connect the
sample lines as follows:
Positive Pressure Only: Connect the
sample line to H; Lremains open to the
atmosphere.
Negative Pressure Only: Connect the
sample line to L; Hremains open to the
atmosphere.
Two Negative Samples: Connect higher
negative sample to L; lower sample to H.
Two Positive Samples: Connect higher
positive sample to H; lower sample to L.
One Positive and One Negative: Connect
positive sample to H; connect negative
sample to L.
ELECTRICAL CONNECTIONS
(FIGURE 3)
Before pressure is applied to the diaphragm,
the switch contacts will be in the normally
closed (NC) position as shown in Figure 3.
Connect the application wiring to the corre-
sponding switch terminals, NC, NO, and C.
FIELD ADJUSTMENT
(FIGURE 4)
The adjustable set point range of the RSS-
498 is 1.0" w.c. to 4.0" wc., ±0.05" w.c. The
switch leaves the factory calibrated at 1.0"
w.c. To adjust the set point, insert the 1⁄16"
hex wrench (provided with the kit) into the
adjusting screw located between the mount-
ing feet on the underside of the switch.
Holding the switch so that the diaphragm
is vertical, rotate the adjusting screw clock-
wise to the desired set point. The maximum
Model
RSS-498-013
AIR PRESSURE SENSING SWITCH KIT WITH ADJUSTABLE SET POINT
