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PV500-34 05/03 6 Section 34
STEAM WITH SINGLE-WALL / DOUBLE-WALL (con't)
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.