Powers 595 Series 11 Self-Operating Temperature Regulators - Type WM 3-Way Water Mix - Manual (Page 9)

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• Temperature of discharge water too low
1. Temperature adjusting nut assembly set too low. Refer to
Adjust Set Point.
2. A radical drop in the hot water supply temperature or pres-
sure. Check supply waters.
3. Valve cannot close against cold inlet. Foreign material may be
caught between the disc and the valve plug seat. Refer to
Replacing the composition disc for disassembly. Clean.
• Temperature of discharge water too high
1. Temperature adjusting nut assembly set too high. Refer to
Adjusting Set Point.
2. Thermal system failure. Refer to Testing the Thermal
System.
3. Incorrect piping to valve. Refer to Operation and/or
Installation.
4. Bulb is poorly positioned and/or oriented, and will not control
the actual temperature of the heating/cooling medium. Refer
to Install Bulb.
5. Incorrect type of bulb is being used. See Table on page 11.
6. Pressure differential is greater than allowable pressure drop.
Refer to Water Mixing Capacities tables.
7. Disc is worn. Replace disc (refer to MAINTENANCE).
8. Valve cannot close against hot inlet. Foreign material may be
between the disc and the valve plug seat. Refer to Replacing
the composition disc for disassembly. Clean.
9. Packing gland assembly is too tight, locking valve stem.
Loosen packing gland assembly and lubricate if desired.
10. Bent valve stem; need to replace. Refer to Maintenance for
disassembly instructions.
• Chattering of Valve
1. Regulator installed with the flow of the control medium in
reverse of arrow direction on valve body.
2. Pressure differential too high, refer to Water Mixing
Capacities tables for correct pressure differential range.
• Constant rise in mixed water temperature
1. A constant rise in temperature may indicate the thermal sys-
tem is leaking charge and/or the valve has failed with the port
for Hot water fully or partially open.
6. The distance between the marks is the valve plug travel. This
should correspond with the TRAVEL value in the VALVE
DIMENSIONS table on page 10. No movement or only par-
tial movement indicates the thermal system is defective
and should be replaced with a new system.
PREVENTIVE MAINTENANCE
Once every three months, inspect the Regulator as follows:
1. Visually check for leaks from the valve body joints, piping-to-
valve connections, packing and stem areas.
2. Visually check for excessive corrosion on the regulator, includ-
ing the bellows, capillary, bulb, thermal system legs, bridge,
and yoke. Also check for excessive corrosion on the valve
body.
3. Perform the instructions in Testing the Thermal System.
Less than full valve travel may indicate a leak in the bellows,
capillary, or bulb, or other problems. This may result in exces-
sive temperature in the process.
4. Test the temperature adjusting nut assembly for freedom of
movement (see Adjust Set Point for instructions).
5. Remove bulb from the process fluid and check for excessive
corrosion, or erosion that may weaken the bulb and/or cause
thermal system failure.
TROUBLESHOOTING
• Erratic temperature control (valve cycles too hot/too cold)
1. Highly fluctuating supply pressures.
2. Sticking stem caused by packing gland assembly too tight,
locking valve stem. Loosen packing gland assembly and lubri-
cate if desired.
3. Sticking stem caused by bent valve stem or valve stem not
properly lubricated. Refer to Maintenance for replacement.
4. Valve sized incorrectly. Verify valve selection.
5. Regulator is controlling at incorrect set point. Refer to Adjust
Set Point.
6. Bulb is poorly positioned and/or oriented, and will not control
the actual temperature of the heating/cooling medium. Refer
to Install Bulb.
7. Incorrect type of bulb is being used. See Table on page 11.
WARNING: Failure of the thermal system will result
in a constant rise in temperature (or constant high
temperature) of the fluid which you are trying to
control.