White Rodgers 770-1 Manuel utilisateur
Type 770-1 Air Switch
With SPDT Switch Action
(Responds to Positive, Negative, or Differential Pressure)
INSTALLATION INSTRUCTIONS
FAILURE TO READ AND FOLLOW ALL INSTRUCTIONS CAREFULLY BEFORE
INSTALLING OR OPERATING THIS CONTROL COULD CAUSE PERSONAL
INJURY AND/OR PROPERTY DAMAGE.
DESCRIPTION
The Type 770-1 has an SPDT switch that can be actu-
ated by a positive pressure, negative pressure, or a
differential of pressure. These features, plus its field ad-
APPLICATIONS
justable “operating range”, give this control unmatched
versatility on a wide variety of applications, some of
which are shown below.
P
Power Humidifiers
Switch permits unit to operate when-
ever there is proper air movement.
Electronic Air Cleaners
Switch permits power to cleaner
whenever blower of system is
operating
N
Natural Draft Boilers
Switch signals insufficient draft,
provides safety limit to stop firing
on lack of draft, starts again on suf-
ficient draft.
N
STACK
Induced Draft Boilers
Proves operation on I.D. fan by sam-
pling draft or air flow.
Shuts off firing equipment on fan
failure.
D
N
Duct Strip Heaters
Switch proves air movement across
heaters by positive pressure in front
of heater. Turns off heater to prevent
burn-out on insufficient air flow.
P
Process Drying
Switch monitors negative pressure to
stop conveyor or process, and pro-
vides alarm signal on fan failure.Ideal
for bulk chemicals, food processing,
grain drying.
N
Refrigeration Equipment
Switch responds to pressure drop
across refrigeration coils to signal
alarm condition or automatically initi-
ate or terminate defrost cycle.
D
Gas-Fired Units
Switch proves sufficient air flow before
permitting gas valve to open and igni-
tion to occur.
P
Forced Draft Boilers
Proves operation of blower by sam-
pling positive or negative pressures
for firing control and safety.
N
P
DN
P
D
Legend
Negative Pressure
Positive Pressure
Pressure Differential
Pressure Sample Line
Operator: Save these instructions for future use!
www.white-rodgers.com PART NO. 37-4898B
Replaces 37-4898A
0843
2
SPECIFICATIONS
Electrical Rating. . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 AMP 125/250/277 VAC N. I.
1/4 HP 125 VAC.
1/2 HP 250 VAC.
Electrical Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . Single pole, double throw snap action switch
Control Setpoint. . . . . . . . . . . . . . . . . . . . . . . . . . . . Adjustable
Field Adjustable . . . . . . . . . . . . . . . . . . . . . . . . . . . . On pressure rise at .05 to 12” w.c.
Conduit Opening . . . . . . . . . . . . . . . . . . . . . . . . . . . 7/8” diameter opening accepts 1/2” conduit
Recommended Operating Position . . . . . . . . . . . . . Diaphragm vertical
Operating Temperature Range . . . . . . . . . . . . . . . . -40 to 180oF
Sample Line Connectors . . . . . . . . . . . . . . . . . . . . . Male externally threaded 7/16” -24 UNS 2 A thread complete
with nut and self aligning ferrule.
Sample Line Connections . . . . . . . . . . . . . . . . . . . . Connectors will accept 1/4” O.D. rigid or semi rigid tubing. Slip on
tubing adaptors optional
MOUNTING INSTRUCTIONS
The air switch must be mounted to a vertical surface,
as shown in above drawings to assure that diaphragm
will be in a vertical plane.
SEE LAST PAGE FOR MOUNTING DIMENSIONS
WIRING
All wiring should be done according to local
and national electrical codes and ordinances.
NOTE
The SPDT switch can be actuated by a positive or
negative pressure, or by a differential of pressure. This
control is ideally suited for residential applications such
as Electronic Air Cleaners and Humidifiers, but it is
equally well suited for commercial installations, includ-
ing applications where alarm circuits are required.
CN.O. N.C.
ELECTRONIC
AIR CLEANER
NEUTRAL
HOT
120 V.A.C.
CN.O. N.C.
AIR SWITCH
GROUNDING WIRE
HUMIDIFIER
TYPE 2268-32
HUMIDIFIER CONTROL
BLACK
120 V.
WHITE
BLACK
WHITE
LIRE
NEUTRAL
AIR SWITCH
HI HN N L
H.C.
NO. C
Fig. 1 - SPDT Switch of Type 770-1
Fig. 2 - Typical Air Cleaner Installation
Fig. 3 - Typical Humidifier Installation
(Without pressure applied to diaphragm,
switch contacts are in position shown.)
3
WIRING
DIAPHRAGM
EF
NEGATIVE ONLY
HIGHER NEGATIVE
LOWER POSITIVE
POSITIVE ONLY
LOWER NEGATIVE
HIGHER POSITIVE
Male externally threaded with nut and self-aligning ferrule.
Positive Pressure Only:
Connect sample line to E; F remains open to atmosphere
Negative Pressure Only:
Connect sample line to F; E remains open to atmosphere
Two Negative Samples:
Connect highest negative sample to F; lower sample to E.
Two Positive Samples:
Connect highest positive sample to E; lower sample to F.
One Positive and One Negative:
Connect positive sample to E; connect negative sample to F
Sample Lines
FILTER
Fan operation or true airflow
with little or no static pressure,
probe must be perpendicular to
fl o w .
Fan operation and true air flow
with varying amounts of static
pressure. Probe must be per-
pendicular to flow.
Fan operation or air flow with
no static pressure.
Suction or fan operation
Prove positive static pressure
Negative pressure increases as
filter gets dirty.
3 Ways to Prove Filter on Positive Pressure
Positive static pressure Diff. across Flow is reduced
increases as the filter filter changes as filter
gets dirty. as it gets dirty gets dirty.
Location of Sample Lines
Pressure Conversion Table
1” Water = .0361 lbs/sq. in. or .0735 in. Mercury
1” Mercury = 13.6 in water or .491 lbs/sq. in.
1 PSI = 27.7 in. water or 2.036 in. Mercury
5-5/8
5-15/16
3-7/8
1-15/16
3/16 DIA. - 2 HOLES
AIR SWITCH MOUNTING BRACKET
1/4 HOLE FOR TUBING
ADJUSTMENT
Merely turn the knurled knob clockwise to field adjust the “operate range” from .05” to 12.0” W.C.
MOUNTING DIMENSIONS
www.white-rodgers.com
White-Rodgers is a division
of Emerson Electric Co.
The Emerson logo is a
trademark and service mark
of Emerson Electric Co.
HOMEOWNER HELP LINE: 1-800-284-2925
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