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 fi eld ad-
APPLICATIONS
justable “operating range”, give this control unmatched
versatility on a wide variety of applications, some of
which are shown below.
P
Power Humidifi ers
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 fi ring
on lack of draft, starts again on suf-
fi cient draft.
N
STACK
Induced Draft Boilers
Proves operation on I.D. fan by sam-
pling draft or air fl ow.
Shuts off fi ring 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 insuffi cient air fl ow.
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 suffi cient air fl ow 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 fi ring control and safety.
N
P
D
N
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
