PVI Industries U-TUBE SINGLE-WALL PV500-34 Manual De Usuario

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b.  Cause:  Steam valve(s) not fully opening 

Solution:  Check steam pressure before and after steam valve. The pressure drop should not 
be more than half of the inlet pressure. Check valve for blockage. Check linkage for adjustment. 
Check modulating signal (if applicable). Check the supplied voltage to the valve coil. 

 
c.  Cause:  Piping flow restricted. 

Solution:  Calculate the flow velocity and expected friction loss. If excessive, larger inlet and 
outlet piping are necessary. 

 
d.  Cause:  Main valve malfunction. 

Solution:  Refer to the valve manual for instructions on main valve repair. 

 

e.  Cause:  Main valve undersized. 

Solution:  Check steam pressure before and after steam valve. Check valve capacity against 
the load. If insufficient, increase trim or valve size.  

a.  Cause:  Insufficient recovery  

Solution:  If the thermostat or controller is always open, then the outlet temperature will vary 
with load. See above for causes of insufficient recovery. 

 
b.  Cause:  Malfunctioning thermostat  

Solution:  Measure the tank temperature near the thermostat and compare to setpoint. The 
thermostat should turn on and off within 5°F of setpoint. 

 

a.  Cause:  Flashing condensate  

Solution:  Pinging, rattling or banging noises are usually the result of condensate flashing to 
steam. Condensate not draining properly. Check that there is not excessive condensate lift. 
Check the sizing of the trap.  Check that the condensate receiver is not pressurized.  Check that 
there is no blockage in the condensate line from the trap to the receiver. Unclog any strainers in 
the system. 

a.  Cause:  Plumbing connection loose  

Solution:  Check and tighten plumbing connection. 

 
b.  Cause:  Double-wall heat exchanger tube leak  

Solution:  If one of the tube walls is breached, a double-wall heat exchanger will leak at the 
joint between the tubesheets. Isolate the heater and replace the heat exchanger.