PVI Industries PV500-25 - Manual (Page 13)

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Steam Heater
13
PV500-25 06/12
8 TROUBLESHOOTING NOTES
Problem:
1. No hot water at even low flow
a. Cause: Steam valve(s) not opening.
Solution: Check that electrical coils are energized. If not, trace wiring problem. If so, the valve may be
faulty, the steam pressure inadequate to open the valve (< 5 psi depending on the valve), or the linkage (if
applicable) is out of adjustment.
b. Cause: Condensate flow is blocked.
Solution: Float-type traps will not open if the inlet steam pressure exceeds the trap rating. Check steam
pressure against the rating stamped on the trap. Check that there are no valves or clogged strainers
between the heat exchanger and the condensate receiver.
c. Cause: PGM system tripped.
Solution: The pressure gradient monitoring option prevents the steam valve from opening if the water
pressure in the tank is within 10 psi of the steam pressure. Correct water pressure problem.
Problem:
2. Heater recovery is slow or outlet temperature is below setpoint:
a. Cause: Steam supply insufficient.
Solution: Loss of steam delivery pressure, see below.
b. Cause: Condensate not draining.
Solution: Check that there is not excessive condensate lift. For low pressure steam, any lift at all may
affect performance. 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.
c. Cause: Condensate trap not operating.
Solution: If the condensate temperature near the heat exchanger is considerably less than the steam
temperature, then condensate is being backed up into the heat exchanger. Check that the supply steam
pressure does not exceed the trap pressure rating. Check the trap for blockage or mechanical failure.
Check that the trap is sized sufficiently for the load.
d. Cause: Heat exchanger is breached.
Solution: If excessive condensate is draining, the heat exchanger may have a leak and be filling with
water.
e. Cause: Heat exchanger is fouled.
Solution: Inspect the heat exchanger for excessive scaling or fouling on the water side.
f. Cause: Abnormal operating conditions.
Solution: The water temperature has a significant effect on the efficiency of the heat exchanger. Check if
the setpoint is higher than specified. Confirm the measured flow rate with meters or by volume and rate.
Check that there are no other loads on the heater.
Problem:
3. Steam delivery pressure to heat exchanger is low or drops off:
a. Cause: Low supply steam pressure.
Solution: Unclog strainer. Check for blockage or restrictions in the line between the boiler and the water
heater. Check for low boiler output or upstream blockage and make necessary corrections.
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.