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SYMPTOM
Steam trap is not functioning properly.
The header P-traps are not draining.
The steam line has been taken from
the bottom of the steam source or is
not sloped properly.
The steam main is overloaded with water.
Water is spitting from the
discharge manifolds
Vertical discharge manifolds are not plumb.
Horizontal headers are not level.
Vertical discharge manifolds are
installed upside down.
Check valve sizing to maximum
manifold capacity.
Valve is not open.
There is no steam available.
Steam does not
There is a change in steam pressure.
discharge from the
manifolds when the valve
is open
Steam is not visible.
Y-strainer may be clogged.
There is no power.
There is no control signal.
Control polarity has been reversed.
Steam valve will not open
Actuator is not working.
There is high steam pressure.
Valve has been installed incorrectly.
There is no control signal.
Control polarity has been reversed.
Actuator is not working.
Steam valve will not close
There is high steam pressure.
Valve has been installed incorrectly.
Control signal is not at full range.
Control polarity has been reversed.
Steam valve is leaking
Actuator is not working.
There is high steam pressure.
LEGEND
AHU — Air-Handling Unit
Table 50 — Humidifier Troubleshooting
POSSIBLE CAUSES
267
POSSIBLE REMEDIES
Clean or replace non-functioning steam trap on the valve/trap
assembly.
Clean and check that plumbing runs to gravity drain. Check that trap
height exceeds the static pressure of the duct/AHU, especially if it is
under negative pressure.
Change line to take off from the top and check proper slopes.
Locate cause and correct problem.
Make manifolds plumb.
Make headers level.
Reinstall correctly.
Resize valve within manifold capacity.
Open valve.
Verify that steam is available.
Verify that the steam pressure has not changed. Excessively high pres-
sure could jam the valve.
Carefully place a mirror or metal object close to one of the steam dis-
charge slots. If it fogs, steam is discharging, but evaporating very quickly.
This is not a problem. NEVER PLACE YOUR HAND OVER OR NEAR
THE STEAM DISCHARGE SLOTS.
Clean or replace Y-strainer.
Verify and, if necessary, correct power or air pressure to the valve
actuator.
Verify and, if necessary, correct control signal or pressure range to the
valve actuator.
Verify and, if necessary, correct control signal polarity to the valve
actuator.
Remove actuator to verify that it is operational. Clean or replace jammed
valve.
Verify that the steam pressure has not changed. Excessively high pres-
sure could jam the valve.
Verify proper valve orientation. Electric valves must face upward.
Verify and, if necessary, correct control signal to the valve actuator.
Verify and, if necessary, correct control signal polarity to the valve
actuator.
Remove actuator to verify that it is operational. Clean or replace jammed
valve.
Verify that the steam pressure has not changed. Excessively high pres-
sure could jam the valve.
Verify proper valve orientation. Electric valves must face upward.
Verify and, if necessary, correct full-range control signal to the valve
actuator.
Verify and, if necessary, correct control signal polarity to the valve
actuator.
Remove actuator and test to verify that it is operational. If not, clean or
replace jammed valve.
Verify that the steam pressure has not changed. Excessively high pres-
sure could jam the valve.
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