WHEN INSTALLING THIS PRODUCT. . .
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous
2. Check the ratings given in the instructions and on the
product to make sure the product is suitable for your
3. Installer must be a trained, experienced, flame safe-
guard control technician.
4. After installation is complete, check out product
operation as provided in these instructions.
1. Disconnect power supply before beginning in-
stallation to prevent possible equipment dam-
age 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.
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), be-
cause mercury in the switch freezes at this temperature.
When used with steam boilers, always mount the con-
troller above the water line in the boiler. A steam trap
(siphon loop) must always be connected between the con-
troller 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 pres-
sure 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
Fig. 2—Right and wrong mounting of a steam
trap (siphon loop), with approximate dimen-
sions in in. (mm).
4-1/2 TO 5-1/2
(114.3 TO 139.7)
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.
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
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.
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
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.