In the course of using a trap, if you encounter a non-drain condition, whether it is a cold or hot trap, it may result in a loss of system efficiency. The following is a detailed troubleshooting guide designed to help users better understand and solve trap problems.
Cold Valve Not Draining Possible Causes:
Design or pressure problems:
The original design pressure may be inaccurate or the valve seat holes may have become enlarged through wear and tear with use.
pressure reducing valve has failed, resulting in actual pressure being higher than design.
Boiler pressure gauge reading is low and does not reflect true pressure.
High vacuum in the return line increases the differential pressure beyond the operating range of the trap.
Fluid path is obstructed:
The strainer in front of the trap may be clogged.
Other valves in the pipeline are damaged, or the pipeline or elbow is clogged internally.
Mechanical failure:
Mechanical parts inside the trap are worn and need to be repaired or replaced.
Dirt Clogging:
The trap body is clogged with dirt. It is recommended that a strainer be installed and drained periodically.
Problems with specific types of traps:
For inverted bucket type traps, the float bucket air vent may be clogged with dirt and a strainer should be installed or the air vent enlarged.
Air blockage can occur if the air vent of float type traps is not clear.
In thermostatic traps, the bellows element may be damaged by water shock, causing the valve to close.
Disc type traps may be installed in the wrong direction.
Possible reasons for a thermostatic trap not draining:
No condensate flow to the trap:
Trap may be installed on a leaking bypass valve.
Siphon discharge line cracked or damaged in dryer drum.
Vacuum in water heater coil preventing discharge, vacuum breaker may be installed between heat exchanger and trap.
Loss of steam:
Valve will not close, possibly due to scale clogging seat holes or worn parts.
Inverted bucket type traps do not operate, possibly due to sudden or frequent changes in steam pressure. It is recommended that the trap be installed below the collection point.
The thermostatic element of float-type traps may be damaged.
Continuous Discharge Problems:
If an inverted bucket or disc trap discharges continuously, or if a float-type or thermostatic trap discharges fully open, the trap may have been selected too small or the water supply conditions may be abnormal. Consider replacing the large valve, installing another trap in parallel, or changing the water supply conditions.
Slow heating problem:
If the trap is working properly but the heating unit is not heating properly, this may be due to part of the unit being shorted out, the trap selection being too small, or insufficient air handling capacity. It is recommended to install one trap on each line, try a larger trap, or use an auxiliary air vent.
Other troubleshooting:
If the trap discharges normally at atmospheric pressure but has problems when connected to the return line, check to see if back pressure is reducing the trap’s discharge, the return line is clogged or there is an excess vacuum.
Trap Troubleshooting Guide
