Page 1
L404A-D,F; L604A,L,M
Pressur etr ol® Contr ollers
L404 and L604 Pressuretrol® Controllers are
line voltage pressure controllers that provide operating control, automatic limit protection, or manual
reset limit protection for pressure systems of up to
300 psi (21.1 kg/cm2 or 2068 kpa).
■ Can be used with steam, air, non-combustible gases,
or fluids non-corrosive to the pressure sensing element.
■ Stainless steel diaphragm (except 300 psi [21.1 kg/
2
(2068 kPa)] models) also allows use with am-
cm
monia, oxygen, distilled water, and similar media.
■ L404B is recommended for supervision of atomiz-
ing medium pressure in oil burner systems.
■ Models are available with spst, spdt, or dpst switch-
ing and in variety of operating ranges.
■ Dustproof, trouble-free mercury switches (all mod-
els except L404F, which has snap-acting switch).
■ Automatic reset models have adjustable, subtractive
differential (except L604M).
■ Trip-free mechanism on manual reset models as-
sures that limit function of controller cannot be
defeated by jamming reset lever.
■ Screw adjustments made on top of case.
■ Scaleplates marked in English (psi) and Metric
■ L404F models available with European enclosure,
■ Clear plastic cover on case to observe pressure set-
■ Leveling indicator visible through cover.
■ Hexagonal fitting with 1/4-18 NPT internal threads
■ Surface mount is available using screws through
CONTENTS
Specifications ................................................ 2
Ordering Information.................................... 2
Installation .................................................... 5
Setting and Checkout..................................... 8
Service Information ..................................... 10
2
(kg/cm
British Standard Pipe Threads, ground screw, and
scaleplates marked in kg/cm
tings and switch action.
for direct mounting to 14026 Steam Trap (siphon
loop).
holes (knockouts) in case backing.
) units.
2
and either psi or kPa.
L. Z. • Rev. 3-95 • ©Honeywell Inc. 1995
60-2150-10
Page 2
L404A-D,F; L604A,L,M
SPECIFICATIONS • ORDERING INFORMATION
Specifications
TRADELINE® MODELS
TRADELINE® models are selected and packaged to
provide ease of stocking, ease of handling, and maximum
replacement value. Specifications of TRADELINE
®
controls are the same as those of standard models except as
noted below.
®
TRADELINE
L604A Pressuretrol® Controllers—Available in 2 to 15, 5 to
50, 10 to 150, and 20 to 300 psi (.14 to 1.1 kg/cm
103 kPa], .4 to 3.5 kg/cm
MODELS AVAILABLE:
2
[34 to 345 kPa], .7 to 10.6 kg/
2
[14 to
cm2 [69 to 1034 kPa], and 1.4 to 21.0 kg/cm2 [138 to
2068 kPa]) .
ADDITIONAL FEATURES: TRADELINE® pack with
cross-reference label.
STANDARD MODELS
MODELS: L404A-D,F and L604A,L,M Pressuretrol® Con-
trollers. See Table 1. A 14026 Steam Trap (siphon loop)
is available, except where noted in Table 1. The steam
trap is necessary for boiler installations.
SWITCH(ES): Mercury switch(es) in all models except the
L404F, which has a Micro Switch snap-acting switch.
PRESSURE SENSING ELEMENT: Stainless steel dia-
phragm (brass bellows in 300 psi [21.1 kg/cm
(2068 kPa)] models).
MAXIMUM AMBIENT TEMPERATURE: 150!F (66!C).
MINIMUM AMBIENT TEMPERATURE: Minus 35!F
(minus 37!C); also refer to the note in the Location and
Mounting section.
ADJUSTMENT MEANS: Screws on top of controller case.
Scales are marked in psi and kPa.
ELECTRICAL CONNECTIONS: Internal screw terminals;
hole in side of case for 1/2 in. conduit.
MOUNTING MEANS: Hexagonal fitting on diaphragm has
1/4-18 NPT internal threads for mounting on a pipe or
steam trap (siphon loop). Also can be surface-mounted
using screws through two holes (knockouts) in back of
case.
2
,
When purchasing replacement and modernization products from your TRADELINE® wholesaler or distributor, refer to the Tradeline
Catalog or price sheets for complete ordering number, or specify—
1. Order number (TRADELINE® model, if desired).
2. Operating range (see Table 1).
3. Model without steam trap, if desired and available (see Table 1, Note b).
4. Optional specifications, if desired (see Table 1).
5. Replacement parts, if desired.
6. Accessories, if desired.
If you have additional questions, need further information, or would like to comment on our products or services, please write or phone:
1. Your local Home and Building Control Sales Office (please check the white pages of your phone directory).
2. Home and Building Control Customer Relations
Honeywell, 1885 Douglas Drive North
Minneapolis, Minnesota 55422-4386
In Canada—Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario M1V 4Z9. International Sales and
Service Offices in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France, Germany, Japan, Mexico,
Netherlands, Spain, Taiwan, United Kingdom, U.S.A.
60-2150—10 2
Ordering Information
Page 3
L404A-D,F; L604A,L,M
SPECIFICATIONS
TABLE 1—MODELS AVAILABLE.
Switching
Action on
Pressure Rise
Model
L404A spst, breaks
L404B
L404C spst, breaks
L404D spst, makes
L404F spdt snap-acting
L604A 2 isolated spst
L604L spdt circuit
L604M spdt circuit
a
Scaleplates are marked in both psi and kg/cm
b
Model available with special fixed low differential. Switch rated for 0.5A at 120 Vac.
c
L404A,B and L604A models are available with 1 to 6 psi midscale subtractive differential in 2 to 15 psi models.
d
Brass bellows replaces stainless steel diaphragm. Not suitable for use with ammonia, oxygen, or other corrosive materials.
e
Model available with minimum operating pressure of 1.25 psi (0.09 kg/cm2 or 8.62 kPa) and minimum subtractive differential of 0.5 psi
(0.035 kg/cm
f
Model available with special fixed low differential. Switch rated for 0.5A at 120 Vac.
g
L404C,D and L604L models are designated as Manual Reset 2 controllers; the trip-free reset mechanism does not permit the controller to
to Setpoint
circuit
i
spst, makes
circuit
circuit
circuit
switch,
R-W, breaks R-B
circuits, or 1
j
spdt,
makes R1-
W, breaks R2-B
makes R-W,
breaks R-B
makes R-W,
breaks R-B
2
or 3.45 kPa).
h
makes
2 to 15
10 to 150
20 to 300
2 to 15d,
10 to 150
20 to 300
10 to 150
20 to 300
10 to 150
10 to 150
20 to 300
10 to 150
20 to 300
10 to 150 .66 to 10.1 69 to 1034 fixed: 3.5 psi (24.1 kPa) 225 15.8 1550
Operating Ranges
psi kg/cm
b,c
.14 to 1.0
b
d
c,e,f
e,b
d
d
i
d
c
d
.35 to 3.5
.66 to 10.6
1.4 to 21.0
.14 to 1.1
.35 to 3.5
.66 to 10.6
1.4 to 21.0
.14 to 1.0
.35 to 3.5
.66 to 10.6
1.4 to 21.0
.14 to 1.0
.66 to 10
.14 to 1.0
.35 to 3.5
.66 to 10
1.4 to21.0
.14 to 1.0
.35 to 3.5
.66 to 10
1.4 to21.0
2
5 to 50
5 to 50
2 to 15
5 to 50
2 to 15
2 to 15
5 to 50
2 to 15
5 to 50
2 to 15 .14 to 1.0 14 to 103 manual resetg
2
a
kPa psi kg/cm
14 to 103
34 to 345
69 to 1034
138 to 2068
14 to 103
24 to 345
69 to 1034
138 to 2068
14 to 103
34 to 345
69 to 1034
138 to 2068
14 to 103
69 to 1068
14 to 103
34 to 345
69 to 1034
138 to 2068
14 to 103
34 to 345
69 to 1034
138 to 2068
Midscale Subtractive Differential
2 to 6
4 to 12
8 to 16
15 to 40
2 to 6
4 to 12
8 to 16
15 to 40
2 to 6
6 to 14
10 to 22
20 to 50
2 to 6
4 to 12
8 to 16
15 to 40
(Adjustable)
2
.14 to .41
.28 to.82
.56 to 1.10
1.04 to 2.76
.14 to .41
.28 to .82
.56 to 1.10
1.04 to 2.76
manual reset
(fixed, subtractive differential)
manual reset
(fixed, subtractive differential)
.14 to .41
.41 to .97
.69 to 15.2
1.4 to 3.5
.14 to .41
.28 to .82
.56 to 1.10
1.04 to 2.76
(fixed, subtractive differential)
103 to 276
103 to 276
g
138 to 345
103 to 276
function as an automatic-reset device when the manual reset lever is held in the reset position. The subtractive differential is fixed at the
minimum value of the adjustable differential of the L404A for each corresponding operating range.
h
L404F only; all other models have mercury switches.
i
Model available with sealed bell crank adjustment.
j
Spst switches operate in unison; spdt action when jumper is installed between R1 and R2.
k
Also recommended for supervision of atomizing medium pressure (air or steam) in an oil burner system.
a
Maximum Surge
Pressure
kPa psi kg/cm2kPa
14 to 4
127 to 83
55 to 110
14 to 41
27 to 83
55 to 110
14 to 41
41 to 97
60 to 152
14 to 41
27 to 83
55 to 110
50
3.5
85
225
500
225
500
225
500
225
225
500
225
500
6.0
15.8
35.2
50
3.5
85
6.0
15.8
35.2
50
3.5
85
6.0
15.8
35.2
50
3 5
15.8
50
3.5
85
6.0
15.8
35.2
25
1.8
85
6.0
15.8
35.2
25 1.8 172
1550
3445
1550
3445
1550
3445
1550
1550
3445
1550
3445
345
586
345
586
345
586
345
345
586
172
586
SWITCH CONTACT RATING (in amperes at 50/60 Hz):
Model Load 120 Vac 240 Vac 120 Vdc 240 Vdc
L404 A Full Load
Locked Rotor
Noninductive
L604A,L
b
Full Load
Locked Rotor
Noninductive
L604M Full Load 1. 0 0. 5 1. 0 0. 5
a
L404F (snap-acting) does not have non-inductive or dc ratings.
b
L604A and L have also been tested (and listed by Underwriters Laboratories Inc.) and breaking (not making) a load with a total
rating of 9.8 A full load, plus 360 VA ignition, plus 250 VA pilot duty at 120 Vac.
8.0
a
48.0
10.0
8.0
48.0
10.0
5.1
30.6
5.0
5.1
30.6
5.0
2.4
24.0
5.0
2.0
20.0
8.0
1.2
12.0
2.0
1.0
10.0
4.0
3 60-2150—10
Page 4
L404A-D,F; L604A,L,M
SPECIFICATIONS
DIMENSIONS: See Fig. 1. See Fig. 2 for mounting steam
trap (siphon loop).
WEIGHT: 2 IBC. (0.91 kg).
FINISH: Gray.
APPROVALS:
Underwriters Laboratories Inc. listed (L404A,B,C,D,F;
L604A,L,M only): file no. MP466, vol.10; guide
no. MBPR.
Canadian Standards Association certified (L404A,B,C,D,F;
L604A,L only): file no. LR1620; guide no.400-E-0.
REPLACEMENT PARTS:
129178 Thermoplastic Cover.
14026 Steam Trap (siphon loop)—1/4 in. black iron pipe.
Necessary for boiler installations.
ACCESSORIES:
33312B Knurled Adjustment Knob—with setscrew; fits
on main scale pressure adjusting screw.
4074BWJ Limit Stop Assembly—to limit set point ranges;
includes 129564 Range Stop, 107194 Range Stop
Screw, and 23466 Wrench.
TABLE 2—CONVERSION TABLE (psi to kPa).
Scale-Plate
(psi)
Operating Range
Equivalent
2)
(kg/cm
(kPa)
Scale-Plate
(psi)
Subtractive Differential
Equivalent
2)
(kg/cm
0 to 15 0 to 10 0 to 103 — — —
2 to 15 .14 to1.0 14 to 103 1 to 6
2 to 6
5 to 50 .3 to 3.5 34 to 345 4 to 12
5 to 14
07 to 4
.14 to .4
.3 to .8
.4 to 1.0
5 to 150 .3 to 10.3 34 to 1034 — — —
10 to 150 .7 to 10.3 69 to 1034 8 to 16
10 to 22
20 to 300 1.4 to 20.7 138 to 2068 15 to 40
20 to 50
.6 to 1.1
.7 to 1.5
1.0 to 2.8
1.4 to 3.5
(kPa)
7 to 41
14 to 41
28 to 83
41 to 97
55 to 110
69 to 152
103 to 276
138 to 345
Fig. 1—Mounting dimensions of the L404A,B,C,D,F and L604A,L,M Pressuretrol® Controllers, in in. (mm).
L404A-D,F; L604A,L,M
4-1/2 (114.3) (COVER)
4-11/32 (110.3) (CASE)
1-15/16 (49.2)
3-3/16 (81.0)
1-5/32
(29.4)
2-1/8 (54.0)
RESET LEVER (ON MANUAL RESET MODELS ONLY.)
1
THIS DIMENSION IS 4-27/32 IN. (123.0 MM) ON L604 MODELS WITH A 2 TO 15 PSI (.14 TO 1.0 kg/cm
2
AND 5-3/4 IN. (146.A MM) ON L604 MODELS WITH A 20 TO 300 PSI (1.4 TO 20.7 kg/cm
ONLY ON L604 MODELS WITH A 2 TO 15 PSI (.14 TO 1.0 kg/cm
3
1-61/64 (49.6)
1
1/4-18 NPT
3-7/8
(98.4)
1-13/16
(46.0)
3/16 (4.8) X 21/64 (8.3)
KNOCKOUT (2)
2
2
(14 TO 103 kPa)) OPERATING RANGE.
(138 TO 2068 kPa) OPERATING RANGE.
2-3/4 (69.9)
1-1/16
(27.0)
13/16
(20.6)
1
7/8
(22.2) DIA.
1-1/16
1-3/16 (30.2)
2
(14 TO 103 kPa)) OPERATING RANGE,
(27.0)
1-1/2 (38.1)
1/2 (12.7)
3
13/16
(20.6)
3-23/32
(94.5)
4-31/32
(126.2)
2
M8933
60-2150—10 4
Page 5
WHEN INSTALLING THIS PRODUCT. . .
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous
condition.
2. Check the ratings given in the instructions and on the
product to make sure the product is suitable for your
application.
3. Installer must be a trained, experienced, flame safeguard control technician.
4. After installation is complete, check out product
operation as provided in these instructions.
L404A-D,F; L604A,L,M
INSTALLATION
Installation
Fig. 2—Right and wrong mounting of a steam
trap (siphon loop), with approximate dimensions in in. (mm).
PRESSURE
PRESSUR
CONTROLLER
TEE
GAUGE
CA UTION
1. Disconnect power supply before beginning installation to prevent possible equipment damage or electrical shock.
2. When using the controller with a compressor,
install a dampening device (such as a needle valve,
header, or surge tank) to dampen pulsations that
can damage the controller or reduce its life.
IMPORTANT:
1. Locate the controller where the ambient temperature
will not exceed 150!F (66!C).
2. Use pipe compound sparingly to avoid clogging the
hole in the pipe or diaphragm fitting.
3. Do not tighten the controller by hand by holding the case.
4. Accurately level the controller for proper operation.
LOCATION AND MOUNTING
NOTE: For most accurate operation; add supplemental heat
to installations where the temperature falls below minus
20!F (minus 29!C). Never locate the controller where the
temperature falls below minus 35!F (minus 37!C), because mercury in the switch freezes at this temperature.
When used with steam boilers, always mount the controller above the water line in the boiler. A steam trap
(siphon loop) must always be connected between the controller and the boiler (Fig. 2) to prevent boiler scale and
corrosive vapors from attacking the diaphragm. The loop
on the steam trap must always be perpendicular to the face
of the controller. If the loop is parallel to the controller,
expansion or contraction of the loop tips the controller and
causes the switch to operate inaccurately.
The controller can be mounted (1) alongside the pressure gauge, (2) in a fitting on the boiler provided by the
manufacturer, (3) at a remote location in case of excessive
vibration, or (4) in a special mounting on a low water
cutoff.
1
14026
4-1/2 TO 5-1/2
(114.3 TO 139.7)
BOILER
1 1/4 IN. BLACK IRON PIPE WITH 1/4 - 18 NPT EXTERNAL
TRHEADS ON BOTH ENDS. BEND THE STEAM TRAP
(SIPHON LOOP) TO LEVEL THE CONTROLLER.
STEAM TRAP
(SIPHON LOOP)
CORRECT
BOILER
2-1/4
(57.2)
DIA.
INCORRECT
M8934
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 can clog
the small hole in the fitting and prevent the controller from
operating properly.
To avoid leaks and damage to the case, use a parallel jaw
wrench on the controller’s hexagonal fitting. Do not tighten
the controller by hand by holding the case.
Leveling
A controller with a mercury switch must be accurately
leveled for proper operation. It is level when the leveling
indicator (Fig. 11) hangs freely with its pointer directly
over the index mark inside the back of the case. Level the
controller by carefully bending the steam trap (siphon
loop).
Mounting Alongside a Pressure Gauge
To mount the controller alongside a pressure gauge
(Fig. 2), remove the gauge. In its place, install a steam trap
(siphon loop) with a tee on top. Using elbows and pipe
nipples, mount the controller and pressure gauge on the
ends of the tee. Level the controller after installation.
5 60-2150—10
Page 6
L404A-D,F; L604A,L,M
INSTALLATION
Mounting on a Boiler
If it is not convenient to mount the controller alongside
the pressure gauge, install a steam trap (siphon loop) in the
fitting provided by the boiler manufacturer. If there is no
fitting, mount the steam trap at a location recommended by
the boiler manufacturer. Screw the controller directly to the
steam trap, and level the controller.
Mounting at a Remote Location
If there is excessive vibration at the boiler that can
adversely affect the operation of the controller, mount the
controller at a remote location. All piping from the boiler
must be suitable and solidly mounted. The piping must be
properly pitched to drain all condensation back to the
boiler. A steam trap (siphon loop) must be mounted between the remote piping and the controller. Level the
controller after installation.
Supervision of Atomizing Medium Pressure
(Air or Steam)—L404B
When air or steam is used as an atomizing medium in an
oil burner system, authorities having jurisdiction (approval
bodies and codes) often require a low limit to prevent
opening the main oil valve until sufficient atomizing pressure is present, and to shut down the system when the
atomizing pressure falls too low.
The L404B is recommended for this application. It
makes a circuit when the pressure rises to the set point, and
breaks when the pressure falls to the set point minus the
differential (Fig. 10).
Fig. 3—L404 terminal blocks and internal
schematics.
RISE
RISE
L404A,C L404B,D L404F
BREAKS ON
PRESSURE RISE
TO SETPOINT
MAKES ON
PRESSURE RISE
TO SETPOINT
RISE
W
R
W
B
(SNAP-ACTING)
BREAKS R-B,
MAKES R-W ON
PRESSURE RISE
TO SETPOINT
Fig. 4—L404 terminal block and internal
schematic.
RISE
JUMPER
B
R2
1
R1
W
RISE
B
R
R
W
B
M8941
B
R
W
WIRING
1. Disconnect the power supply before beginning wiring
to prevent electrical shock or equipment damage.
2. Assume all wiring complies with applicable electrical
codes, ordinances, and regulations. Use NEC Class 1 (line
voltage) wiring.
3. For normal installations, use moisture-resistant No. 14
wire suitable for at least 167!F (75!C) when you are using
the controller with a flame safeguard primary control, or at
least 194!F (90!C) when using it with a programming
control.
4. For high temperature installations, use moisture-resistant No. 14 wire, selected for a temperature rating above the
maximum operating temperature.
5. All models have a terminal block inside the cover (Fig.
3 and 4) and a 7/8 in. (22.2 mm) hole in one side for 1/2 in.
conduit, cable, or wires. Remove the front cover by loosening the screw at the bottom of the main scale.
6. Refer to Fig. 5 through 9 for typical hookups. Follow
the burner or boiler manufacturer’s wiring diagram if provided .
7. Make sure the loads do not exceed the Switch Contact
Ratings in the Specifications section.
8. Replace the front cover when wiring is completed.
L604A L604L,M
MAKES R1-W
BREAKS R2-B
ON PRESSURE RISE TO SETPOINT.
SPDT SWITCH ACTION WITH JUMPER INSTALLED;
1
OTHERWISE, TWO ISOLATED SPST SWITCHES.
Fig. 5—L404 used as a limit or as an operating
controller.
SPST
CONTROLLER
L1
(HOT)
POWER
SUPPLY
1
2
1
L2
PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
HIGH LIMIT—L404A OR C BREAKS WHEN PRESSURE RISES
TO SETPOINT.
LOW LIMIT—L404B BREAKS WHEN PRESSURE FALLS TO SETPOINT
MINUS DIFFERENTIAL.
OPERATING CONTROLLER—L404A BREAKS WHEN PRESSURE RISES
TO SETPOINT, AND MAKES AGAIN WHEN PRESSURE FALLS TO
SETPOINT MINUS DIFFERENTIAL.
2
L2
FLAME
SAFEGUARD
CONTROL,
MOTOR, OR
OTHER LOAD
M8935
M8936
60-2150—10 6
Page 7
L404A-D,F; L604A,L,M
INSTALLATION
Fig. 6—L404 with a low voltage relay.
LOW VOLTAGE RELAY
24 VOLT
THERMOSTAT
PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION
1
AS REQUIRED.
1
2
THERM
LOAD
L404
POWER
SUPPLY
Fig. 7—L404F, L604A (jumper installed) used
as a high limit, with an alarm circuit.
SPDT
CONTROLLER
(LOW LIMIT)
2
W
B
R
L1
(HOT)
POWER
SUPPLY
L2
1
L2
ALARM
1
PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
BREAKS R TO W AND MAKES R TO B WHEN PRESSURE
2
FALLS TO SETPOINT MINUS DIFFERENTIAL.
FLAME
SAFEGUARD
CONTROL,
MOTOR, OR
OTHER LOAD
M8937
L1
(HOT)
1
L2
M8940
Fig. 8—L404F, L604A (with jumper installed) or
L604M, used as a low limit, with an alarm
circuit.
SPDT
CONTROLLER
(HIGH LIMIT)
2
W
B
R
L1
(HOT)
POWER
SUPPLY
1
L2
ALARM
1
PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
BREAKS R TO B AND MAKES R TO W WHEN PRESSURE
2
RISES TO SETPOINT.
L2
FLAME
SAFEGUARD
CONTROL,
MOTOR, OR
OTHER LOAD
M8938
Fig. 9—L404F, or L604 with jumper installed,
controlling an M644B motor.
SPDT
CONTROLLER
W
2
B
L1
(HOT)
POWER
SUPPLY
1
2
1
L2
PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
BREAKS R TO B AND MAKES R TO W WHEN PRESSURE
RISES TO SETPOINT.
WHITE
RED
R
BLUE
BLACK
BLACK
LINE VOLTAGE
TWO-POSITION MOTOR
CLOSED
W1
(LOW FIRE)
R1
OPEN
B1
(HIGH FIRE)
L1
L2
M644B
M8939
7 60-2150—10
Page 8
L404A-D,F; L604A,L,M
MERCURY
SWITCH
DIFF.
MAIN
PSI
12
10
8
6
4
2
.1
.3
.5
.7
.8
.6
.4
.2
0
.5
1
20
10
30
40
50
3.5
3
2.5
2
1.5
0
DIAPHRAGM
ASSEMBLY
LEVELING
INDICATOR
POINTER
INDEX
MARK
MANUAL
RESET
LEVER
MAIN SCALE
ADJUSTING
SCREW
DIFFERENTIAL
ADJUSTING
SCREW
SCALEPLATES
DIFFERENTIAL
SETTING
INDICATOR
MAIN SCALE
SETTING
INDICATOR
ADJUSTABLE DIFFERENTIAL ON THE L404A,B,F; L404L WITH A 5 TO
150 PSI (0.34 TO 10.3 kg/cm
2
[34 TO 134 kPa] OPERATING RANGE;
AND L604A MODELS ONLY.
TRIP-FREE MANUAL RESET LEVER ON THE L404C,D AND L604L
MODELS ONLY.
M8943
1
2
1
2
SETTING AND CHECKOUT
Setting and Checkout
SETTING
In all models, the differential is subtractive from the
main scale set point. The upper operating point is determined by the main scale set point, while the lower operating point is determined by the main scale setting less the
differential setting. The L404F and L604A (with jumper
installed), L,M have spdt switching action. Operating points
are shown in Fig. 10.
Fig. 10—L404 and L604 operating points.
MAIN SCALE SETPOINT
(SWITCH BREAKS)
L404A,C
L404B,D
L404F;
L604L,M
PRESSURE
RISE
PRESSURE
RISE
PRESSURE
RISE
SUBTRACTIVE
DIFFERENTIAL
DIFFERENTIAL SETTING
(SWITCH MAKES)
MAIN SCALE SETPOINT
(SWITCH MAKES)
SUBTRACTIVE
DIFFERENTIAL
DIFFERENTIAL SETTING
(SWITCH BREAKS)
MAIN SCALE SETPOINT
(BREAKS R-B, MAKES R-W)
SUBTRACTIVE
DIFFERENTIAL
DIFFERENTIAL SETTING
(MAKES R-B, BREAKS R-W)
1
1
1
2
main scale setpoint. They will not automatically return to
their former positions. To reset one of these controllers,
wait until the pressure falls to the set point minus the
differential (Fig. 10). Then depress the manual reset lever
(Fig. 11) and release it. The controller will not be reset until
you release the manual reset lever. This prevents the controller from becoming an automatic-reset device if the reset
lever is stuck, held in, or tied down.
Fig. 11—Setting a Pressuretrol® Controller.
MAIN SCALE SETPOINT
(MAKES R1-W, BREAKS R2-B)
L604A
PRESSURE
RISE
L404C,D AND L604L MANUAL RESET MODELS HAVE A SMALL, FIXED
1
DIFFERENTIAL. THEY CAN BE MANUALLY RESET WHEN THE PRESSURE
FALLS TO THE MAIN SCALE SETPOINT MINUS THE DIFFERENTIAL.
L604M HAS A SMALL, FIXED DIFFERENTIAL OF 3.5 PSI (0.25 kg/cm
2
OR 24.1 kPa.)
Adjust the main scale set point for the desired operating
pressure by turning the main scale adjusting screw (Fig. 11)
SUBTRACTIVE
DIFFERENTIAL
DIFFERENTIAL SETTING
(BREAKS R1-W, MAKES R2-B)
on the top of the case until the main scale setting indicator
is at the desired value. On an L404A,B,F with a 5 to 150 psi
(.3 to 10.3 kg/cm2 [34 to 1034 kPa]) operating range, or an
L604A, adjust the differential setting by turning the differential adjusting screw (Fig. 11) until the differential
setting indicator is at the desired value. L404C,D and
L604L are manual reset models: see the next paragraph.
The L604M has a fixed differential. The scaleplates are
marked psi and kg/cm2.
Trip-Free Manual Reset Feature
(L404C,D and L604L only)
The L404C breaks, the L404D makes, and the L604L
makes R-W and breaks R-B when the pressure rises to the
60-2150—10 8
2
)
M8942
CHECKOUT
After the controller has is installed, wired, and set, test it
with the system in operation. First allow the system to
stabilize. Then observe the operation of the controller while
raising and lowering its setpoint. Pressure should increase
when the setpoint is raised and decrease when the set point
is lowered.
Also check the make and break points of the controller.
If they do not agree with a separate, accurately calibrated
pressure gauge, a slight adjustment of the scaleplate(s) may
be necessary.
Use accurate pressure testing equipment when checking
out the controller. Do not rely on inexpensive gauges. The
controllers are carefully calibrated at the factory.
Page 9
L404A-D,F; L604A,L,M
SETTING AND CHECKOUT
Boiler Installation
If the controller is being used on a boiler installation, test
it as follows:
1. Note the boiler pressure by checking the boiler pressure gauge. (To perform this test properly, the boiler should
have a pressure reading near the middle of the controller’s
main scale range.)
2. Turn the main scale adjusting screw (Fig. 11) until the
main scale setting indicator on the controller corresponds to
the boiler pressure gauge reading.
3. The L404A or C should break the control circuit(s)
automatically when the boiler pressure gauge reading equals
or slightly exceeds the controller setting.
The L404B or D should make the circuit under the same
circumstances.
The L404F; L604L,M should make the R-W circuit and
break the R-B circuit under the same circumstances.
The L604A should make the R1-W circuit and break the
R2-B circuit under the same circumstances.
4. If the controller is operating properly, turn the main
scale adjusting screw (Fig. 11) until the main scale setting
indicator is at the desired set point.
If a Controller Seems to Operate Improperly
If the controller is suspected of operating improperly, it
may be further checked as follows (Fig. 12):
1. Disconnect all power to the controller, loosen the
cover screw, and remove the cover.
2. Disconnect the wires from the controller.
3. Connect an ohmmeter between the switch terminals.
4. Lower the set point of the controller (simulating a
pressure increase) through a range greater than the differential. The switch should either make or break, depending on
the model of the controller. (An L404A or C should break, an
L404B or D should make, an L404F; L604L,M should break
R-B and make R-W, and an L604A should break R2-B and
make R1-W.) If it makes, the ohmmeter reads zero; if it
breaks, the ohmmeter reads infinity.
5. Raise the set point of the controller (simulating a
pressure decrease) through a range greater than the differential. The switch should break or make, just the opposite of its
action in step 4 (except for the L404C,D and L604L manual
reset models).
NOTE: An approximation of the differential can be made by
observing the change in set point required for a resistance
change from zero to infinity.
6. If the controller operates improperly, replace it.
7. When the controller is operating properly, reconnect
the wires to the terminal block, replace the cover and tighten
the cover screw, and reconnect the power.
CA UTION
Do not put the system into service until you have
satisfactorily completed all applicable tests described in this Checkout section, in the Checkout
section of the applicable instructions for the flame
safeguard control, and any others required by the
burner and boiler manufacturers.
Fig. 12—Checking controller operation using
an ohmmeter.
MAIN SCALE
ADJUSTING SCREW
DIFF.
MAIN
50
3.5
3
12
40
.8
10
2.5
.7
.6
30
2
8
PSI
DIFF. IS
SUBTRACTIVE
OUTPUT
0
.5
1.5
6
.4
20
.3
4
1
.2
2
.5
.1
0
KG
KG
2
CM
2
CM
B
10
0
PSI
R1
W
1
ZERO OHMS
(INFINITY WHEN R-B BREAKS)
R2
W
SETPOINT
DECREASE
R
B
M8944
DIFFERENTIAL
SETTING
INDICATOR
MAIN SCALE
SETTING
INDICATOR
OHMMETER
INPUT
ZERO
ADJ
1 AN L604, WITH JUMPER INSTALLED BETWEEN R1 AND R2, IS SHOWN;
AN L404F OPERATES SIMILARLY (SPDT SWITCHING). AN L404A, B, C
OR D HAS ONLY TWO TERMINALS (SPST SWITCHING); AN L404A
OR C BREAKS AND L404B OR D MAKES WHEN THE SETPOINT IS
DECREASED FAR ENOUGH.
9 60-2150—10
Page 10
L404A-D,F; L604A,L,M
SERVICE INFORMATION
Service Inf ormation
CALIBRATION
The controller was carefully calibrated during manufacturing and should not require recalibration. Most calibration errors are caused by improper leveling. The controller
should be level when the pointer on the leveling indicator is
directly over the index mark (Fig. 11). In some cases, the
leveling indicator may not be accurate enough. The pointer
may be over the index mark, but the controller still may not
be operating within the tolerance of its scale setting. In this
case, carefully bend the steam trap (siphon loop) until the
controller switches properly.
MAINTENANCE
The cover of the controller should be in place at all times
to protect the internal components from dirt, dust, and
physical damage. Routine maintenance should consist of
occasional inspection and blowing or brushing away any
accumulated dirt and dust. To ensure proper functioning of
the controller at all times, perform an operational check of
the entire system during routine maintenance checks.
60-2150—10 10
Page 11
11 60-2150—10
Page 12
Home and Building Control Home and Building Control Helping You Control Your World
Honeywell Inc. Honeywell Limited—Honeywell Limitée
1985 Douglas Drive North 740 Ellesmere Road
Golden Valley, MN 55422 Scarborough, Ontario
60-2150—10 12
Printed in U.S.A. www.honeywell.com/bbc
M1P 2V9
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