Honeywell L404T ユーザーズマニュアル

71-2429—06

4

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.

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.

 

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).

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.

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.

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.

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 

M23885 

1

1  1/4 IN. PIPE WITH 1/4 - 18 NPT EXTERNAL THREADS

ON BOTH ENDS AND 2-1/4 IN. DIAMETER LOOP.