Submittal Sheet

L408J VAPORSTAT
®
CONTROLLERS
65-0287—01 6
Fig. 7. L408J operating points.
Fig. 8. Setting a VaporStat
®
Controller.
Checkout
After the controller has been installed, wired, and set, it should
be tested with the system in operation. First allow the system
to stabilize. Then observe the operation of the controller while
rasing and lowering its setpoint. Pressure should increase
when the setpoint is raised and decrease when the setpoint 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.
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
main scale range.)
2. Turn the main scale adjusting screw (see Fig. 8) until the
main scale setting indicator on the controller
corresponds to the boiler pressure gauge reading.
3. The L408J should make the R-W and break the R-B
circuit automatically when the boiler pressure gauge
reading equals or slightly exceeds the controller setting.
4. If the controller is operating properly, turn the main scale
adjusting screw (see Fig. 8) until the main scale setting
indicator is at the desired setpoint.
If a Controller Seems to Operate Improperly
If the controller is suspected of operating improperly, it may be
checked further as follows (see Fig. 9):
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 setpoint 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. (See Table 1.)
If it makes, the ohmmeter will read zero; if it breaks, the
ohmmeter will read infinity.
5. Raise the setpoint of the controller (simulating a
pressure decrease) through a range greater than the
differential. The switch should break or make, just the
opposite of the result in step 4.
Fig. 9. Checking a VaporStat
®
controller.
M23112
MAIN SCALE
SET POINT
B-R MAKES
(R-W BREAKS)
DIFFERENTIAL
(ADJUSTABLE)
B-R BREAKS
(R-W MAKES)
CONTROL
SET POINT
B R-W
B-R
SWITCH ACTION ON
PRESSURE RISE
INDICATES CLOSED SWITCH CONTACTS.
W
B-R
SWITCH ACTION ON
PRESSURE FALL
W
B R-W
DIFF.
MAIN
OZS kP
IN
4
0
.1
2
8
6
10
14
16
7
6
5
4
3
0
16
12
8
6
2
1
2
3
4
5
6
7
DIAPHRAGM
ASSEMBLY
MAIN SCALE
ADJUSTING
SCREW
DIFFERENTIAL
ADJUSTING
SCREW
SCALEPLATES
DIFFERENTIAL
SETTING
INDICATOR
MAIN SCALE
SETTING
INDICATOR
M22693A
R
W
B
12
4
2
4
14
10
DIFF.
MAIN
OZS kP
IN
4
0
.1
2
8
6
10
14
16
7
6
5
4
3
0
16
12
8
6
2
1
2
3
4
5
6
7
R
W
B
12
4
2
4
14
10
ZERO
ADJ
SET POINT
DECREASE
OHMMETER
INFINITY
(ZERO OHMS WHEN R-W MAKES)
M22694A