be increased.
d. Turn the spring adjustment screw slowly to increase spring tension until the
pressure on the down stream side of the valve has dropped to “0” and there
is no sound of flow through the valve. Do not turn spring adjustment past
this point.
If the valve will not open with air on the diaphragm, spring is adjusted too
tightly.
(1) Release all air pressure from the valve diaphragm.
(2) Apply steam pressure to the valve.
(3) Loosen tension on the spring until steam begins to seep through the
valve.
(4) Slowly, tighten spring tension until flow stops.
(5) Do not turn spring adjustment past this point
.
4. ADJUSTMENT OF 3-WAY AIR OR WATER OPERATED VALVES
a. Turn thermostat down so that no air pressure is on the valve diaphragm. If
unit continues to heat, valve spring tension needs to be increased.
b. Shut off heating medium.
c. Disconnect stem coupling (A).
d. Lift lower stem (B) and hold against upper valve seat.
e. Turn adjustment screw (C) until there is approximately a 1/16-inch gap
between the two stem halves.
f. Apply air pressure to valve diaphragm so that stem halves are aligned and
re-connect stem halves.
g. If valve will not open with air on the diaphragm, spring tension should be
decreased.
h. Adjustment is essentially the same as if spring tension were increased except
the adjustment screw is turned in the opposite direction.
5. ADJUSTMENT OF PILOT OPERATED VALVES
a. Pilot operated valves such as Spence or Spirax/Sarco are not
fail safe. These
valves have a liquid or gas filled thermo-static bulb and if this bulb loses its
charge, the valve will go to its full open position and cause overheating of
the water heater. This situation should be considered before attempting to
adjust these valves.
b. Spirax/Sarco Valves
are completely pre-set at the factory and there is no
spring adjustment. Set the thermostat at the desired temperature and no
further adjustment is required.
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