Vulcan-Hart MHB24G, VHX24G5 manual Boiler blowdown solenoid valve clogged and not fully closing

VHX SERIES STEAMER - TROUBLESHOOTING

SYMPTOM		POSSIBLE CAUSES
Boiler Slow to Pressurize	1.	Low water supply pressure, inline water strainer clogged or fill
(over 15 min. to achieve operating		solenoid valve malfunction. See "INLINE WATER STRAINER
pressure)		CLEANING" and "FILL AND COLD WATER SOLENOID
		VALVES" in "SERVICE PROCEDURES AND
		ADJUSTMENTS".
	2.	Boiler blowdown solenoid valve clogged and not fully closing.
		Check for a slow leak out of steamer drain. If not able to verify,
		then proceed to step 3. If blowdown solenoid valve appears to
		be functioning properly, then proceed to step 4.
	3.	Turn power switch OFF, disconnect lead wires from blowdown
		solenoid and remove it for inspection.
	4.	A heavy build-up of scalants has coated the interior of the
		boiler, creating an insulating effect. Examine interior of boiler
		as outlined under “BOILER” in "SERVICE PROCEDURES AND
		ADJUSTMENTS".
	5.	Low incoming gas pressure is reducing BTU output.
		A. Verify gas supply line to the steamer is a minimum of one
		inch diameter (ID).
		B. Check incoming line and manifold gas pressures as
		outlined in "GAS MANIFOLD PRESSURE ADJUSTMENT"
		under "SERVICE PROCEDURES AND ADJUSTMENTS".
	6.	Gas valve malfunction.
		A. Check incoming line and manifold gas pressures as
		outlined in "GAS MANIFOLD PRESSURE ADJUSTMENT
		under "SERVICE PROCEDURES AND ADJUSTMENTS".
Boiler will not heat or build pressure.	1.	Gas not on.
	2.	Power/reset switch assembly malfunction.
	3.	Boiler not filling - check fill solenoid for power, clogging or
		malfunction.
	4.	Gas pilot and/or gas manifold pressure low. See "GAS PILOT
		PRESSURE ADJUSTMENT" and "GAS MANIFOLD
		PRESSURE ADJUSTMENT" in "SERVICE PROCEDURES
		AND ADJUSTMENTS".
	5.	Cycling pressure switch open or set too high. Steamer is
		cycling on high limit.
	6.	High limit pressure switch open and not re-setting
		(malfunction).
	7.	Water too "pure" for probes to properly conduct electricity.
		NOTE: Items 8 & 9 see "WATER LEVEL CONTROLS TEST"
		in "SERVICE PROCEDURES AND ADJUSTMENTS".
	8.	Water Level Control malfunction.
	9.	Aux. Water Level Control malfunction.
Pressure relief valve(s) opening or	1.	Pressure overshoot on initial startup or long burner on times
leaking.		under heavy usage.
	2.	Pressure relief valve malfunction.
	3.	Cycling pressure switch set to high.
	4.	High limit pressure switch not set correctly or malfunctioning.

F24700 (October 2001) Page 64 of 68