10
Problem:
2. System Temperature High
a.
Cause:
Bypass gate valve is open.
Solution: Close the valve.
b.
Cause:
Capillary has kink. Sharp bend will
stop signal to pilot.
Solution: Replace actuator or work out by
hand.
c.
Cause:
Actuator range incorrect. The
actuator will not operate beyond
its range.
Solution: Check name plate for correct
temperature range. Replace if
necessary.
d.
Cause:
Temperature adjustment altered.
Solution: Readjust to desired operating
condition.
e.
Cause:
Oversized valve.
Solution: Check valve capacity against the
load. If excessive, install smaller
valve. Steam valves—install a steam
pressure reducing valve to reduce
capacity.
f.
Cause:
Improper stem adjustment.
Solution: Check stem travel by following
instruction no. 8 on page 7.
g.
Cause:
Improper thermostatic bulb location.
Solution: Bulb must be fully into the flow path.
Use reducing bushing instead of
reducing coupling and nipples. In
storage tanks install the bulb near
the center of the tank. There must be
flow past the thermostatic bulb, as a
rule of thumb a recirculating pump
should provide a minimum of 20%
design load at all times.
h.
Cause:
Poor temperature response.
Solution: On units with separable well use
high temperature grease between
the thermostatic bulb and well for
better heat transfer.
i.
Cause:
Thermostatic bulb installed upside down.
Solution: See Figure No. 5 and follow bulb
installation instructions on page 3.
Problem:
3. System Temperature Erratic
a.
Cause:
Thermostatic bulb installed upside down.
Solution: The bulb mounting flange has the
word top stamped in the O.D. This
must be in the up position. The bulb
may also be installed vertically with
bulb end down, flange on top.
b.
Cause:
Capillary has kink or defective
actuator. Sharp bend will stop
signal to pilot.
Solution: Replace actuator or work out by
hand.
c.
Cause:
Thermostatic bulb installed in
poor location.
Solution: Install as close as possible to
thermometer and heater coils in
instantaneous heaters.
d.
Cause:
Insufficient circulation through heater.
Solution: Check circulation system, and
insure sufficient circulation.
Steam Valve Only
e.
Cause:
Condensate not draining.
Solution: Check steam trap for proper sizing
and operation. Trap should drain by
gravity into a vented return line. Avoid
lifts in the return lines.
f.
Cause:
Improper stem adjustment.
Solution: Check stem travel per instructions in
this manual.
Summary of Contents for Bell & Gossett Hoffman Specialty 1140 Series
Page 11: ...11...
