L404F,T,V PRESSURETROL® CONTROLLERS
71-2429—06 4
INSTALLATION

When Installing This Product…

1. Read these instructions carefully. Failure to follow them
could damage the product or cause a hazardous
condition.
2. Check on the ratings given in the instructions and
marked on the product to make sure the product is
suitable for your application.
3. Installer must be a trained, experienced service
technician.
4. After installation is complete, check out the product
operation as provided in these instructions.
IMPORTANT
When making pipe connections, use pipe dope
sparingly to seal the joints; any excess dope may clog
the small hole in the fitting and prevent the controller
from operating properly.

Location and Mounting (L404F)

Locate the L404F where the ambient temperature will not
exceed 66°C (150°F). The L404F can be mounted near the
pressure gauge, at a remote location, in a fitting provided by
the boiler manufacturer, or in a special mounting on low water
cutoffs. The L404F should always be mounted above the water
line in steam boiler applications.
NOTE: For accurate operation, supplemental heat should be
added to installations where temperatures fall below
-29°C (-20°F).
A steam trap must be connected between the L404F and the
boiler (see Fig. 2) to prevent boiler scale and corrosive vapors
from attacking the elbows or diaphragm.
Fig. 2. Steam trap mounting.

Pressure Gauge Mounting

To mount beside a pressure gauge, remove the gauge, and
install in its place the steam trap with a tee on top. Mount the
PressureTrol® unit and pressure gauge on the side of the tee
by means of nipples and elbows (see Fig. 2).

Remote Mounting

Excessive vibration at the boiler may affect the operation of the
L404F. In these cases, the L404F should be remotely located,
subject to the following:
1. All piping must be suitable and properly pitched to drain
all condensation back to the boiler.
2. The remote mounting must be solid.
3. A steam trap must be used at one end of the piping.

Boiler Mounting

If it is not convenient to mount the L404F adjacent to the
pressure gauge, install a steam trap at the location
recommended by the boiler manufacturer, then screw the
device directly to the steam trap.

Location and Mounting (L404T,V)

Location

NOTE: For most accurate operation, supplemental heat
should be added to installations where the
temperature falls below -20°F (-29°C).These
controllers can be mounted at any location in the oil
supply line, depending on the application. Typical
locations are shown in Fig. 3. The low oil pressure
controller should be located upstream from the safety
shutoff valve(s). In a downstream location, there
would be zero pressure when the burner is not
running and the safety shutoff valve(s) is (are) closed.
This could prevent startup or require manual reset
every time the burner is started. The high oil pressure
controller should be located as near to the burner as
possible.

Mounting

Mount the oil pressure controller directly on the main pipe.
Insert a tee in the pipe line, and connect a pipe nipple of
appropriate size to the tee (see Fig. 4). Screw the hexagonal
fitting (1/4-18 NPT internal thread) of the pressure controller to
the pipe nipple. To avoid leaks and damage to the case, use a
parallel jaw wrench on the hexagonal fitting close to the pipe
nipple. Do not tighten the pressure controller by hand by
holding the case.
Make all pipe connections in accordance with approved
standards. Use only a small amount of pipe compound to seal
the connection joints. Excess pipe compound may clog the
orifice in the pipe fitting and prevent the controller from
operating properly.
4-1/2 TO 5-1/2
(114.3 TO 139.7)
BOILER
STEAM TRAP
(SIPHON LOOP)
TEE
PRESSURE
GAUGE
PRESSURE
CONTROLLER
M2
3885
1
1 1/4 IN. PIPE WITH 1/4 - 18 NPT EXTERNAL THREADS
ON BOTH ENDS AND 2-1/4 IN. DIAMETER LOOP.