Installation Instructions P47
Issue Date 0918
© 2018 Johnson Controls
1
Form 997-455, Rev. D
P47 Series
Steam Pressure Limit Controls
Application
The P47 controls are designed
for high limit, cutout, or operating
control applications. When used
as a limit or cutout control, the
P47 is intended primarily to limit
the pressures in steam heating
systems.
The controls which OPEN on a
pressure increase are for use on
high limit, cutout, or operating
applications.
The controls which CLOSE on a
pressure increase are typically
used to deenergize a unit heater
blower when the steam pressure
is below that required for
adequate heating.
The 4-wire, two-circuit models
(P47GA) have two separate sets
of contacts. The main load
contacts (LINE-M2) open on
pressure increase and
simultaneously the auxiliary
circuit (LINE-M1) closes. These
models may be used to limit
steam pressures and energize
an alarm indicator.
The SPDT models (EA and FA)
may be used on open high or
close high applications, and may
also be used to control 3-wire,
two position valves or dampers.
The controls with the lockout
feature require manual reset to
reclose the circuit and can only
be reset after the pressure
normalizes. The reset is “trip-
free” and will not permit restart
until the reset lever has been
pushed and released.
The P47 controls may also be
used for air and non-combustible
gas or liquid applications which are
not harmful to iron, copper, or
brass. Do not install where
ambient temperature exceeds
140°F (60°C) or falls below -30°F
(-34°C).
!
CAUTION:
Risk of
equipment damage.
Never
exceed the maximum
overpressure for the control.
Refer to the table below to
determine the maximum
overpressure.
Control Range
psig (kPA)
Maximum
Overpressure
psig (kPa)
0 to 15
(1 to 100)
50
(345)
20” Hg. Vac. to 50
(-70 to 350)
180
(1240)
0 to 150
(0 to 1000)
300
(2069)
50 to 240
(500 to 1500)
300
(2069)
175 to 425
(1200 to 2930)
540
(3720)
Installation
Mounting
1. Mount the control to the
boiler tap above the water
level. Be sure there is no
shutoff between the control
and the boiler. (Usually there
is a tap for mounting the
control and/or a pressure
gauge on top of the boiler.)
2. Connect the siphon (when
required) between the boiler
and the control so live steam
does not enter the bellows
corrugation. (A siphon is not
supplied as standard with 0 to
15 psig [0 to 103 kPa] range
controls.)
3. The P47 control must be
mounted to a tap separate
from the pressure gauge or
other devices. Refer to Fig. 2
for typical P47 mounting.
4. If the control is not mounted
on the boiler, anchor the
control by two mounting holes
in the back of the case using
the screws supplied. Make
certain the connecting pipes
to the boiler are installed at a
slight angle to permit
condensate to drain through
the siphon back into the
boiler.
5. Put a small amount of pipe
dope or thread sealing tape
on the male threads.
6. To tighten the pressure
connection, use a wrench on
the hexagonal flats of the
bellows pressure connector.
IMPORTANT: Do not tighten the
connection by grasping the
control case and turning.
Never use a pipe wrench on
the bellows cup.
Fig. 1 -- Interior view of two-
pole pressure control with
manual reset
