Dwyer 38R - Manual (Page 21)

Series 38R ••• Self-Acting Temperature Control Valves Operation, Installation & Maintenance Manual
Page 21
TROUBLE SHOOTING GUIDE
PROBLEM: TEMPERATURE REMAINS BELOW THE DESIRED CONTROL POINT
CAUSES CORRECTIONS
1. Adjusting setting too low. 1. Raise setting.
2. Bulb at hot location. 2. Relocate bulb to more representative
average temperature location or add agitation.
3. Stem adjustment too long. 3. Readjust. (See Figure 6)
(Closes with temperature increase)
4. Valve size too small. 4. Replace valve with larger size.
5. Valve inlet pressure too low. 5. Increase supply pressure.
6. Heat exchanger not large enough. 6. Replace with proper capacity.
7. Faulty or undersized steam trap. 7. Install trap of proper capacity.
8. Stem moves into body to open valve. 8. Change to stem moves into body to close valve.
(Opens with temperature increase)
9. Foreign material under seats holding 9. Heat the bulb to open the valve and allow it to
the valve open. larger size.
10. Erosion of seats with resulting 10. Repair or replace valve body assembly.
high leakage.
11. Pressure drop across the valve 11. Reduce pressure drop or replace single seated
is too high. valve with double seated.
12. Stem moves into body to close valve. 12. Change to stem moves into body to open valve.