Vulcan-Hart MHB24G, VHX24G5 manual Board Layout and LED Legend

VHX SERIES STEAMER - ELECTRICAL OPERATION

RELAY BOARD

Board Layout and LED Legend

The relay board Provides a centralized location for wire harness connections and power transfer through board relays (K1-K7) to the other steamer controls. Also, provides a condition or component troubleshooting indicator by utilizing seventeen LED’S on the board to represent the status of the condition or component in the operating sequence. When the condition for the component being monitored is satisfied or activated, an LED will light to indicate its proper operation. If the corresponding LED does not light then the condition or component has not been satisfied or is not activated.

LED LEGEND

LED ON = Condition satisfied or component activated. 1 LED OFF = Condition not satisfied or component de-activated.

LED	DESCRIPTION	LED	DESCRIPTION
N1	Board powered (24vac).	N10	Auxiliary water level satisfied (LLCO) and reset switch
			activated.
N2	Auxiliary water level satisfied (LLCO).	N11	Boiler operating pressure condition satisfied and reset
			switch activated.
N3	High limit pressure switch closed.	N12	Combustion blower ON.
N4	Steamer is ready (ready light "green" is ON).	N13	Combustion blower air pressure switch satisfied.
N5	Auxiliary water level satisfied (LLCO) and reset switch activated.	N14	Ignition module pilot voltage (PV) to board level timing
			circuit.
N6 1	Low water condition exists (N2 LED ON) or previously existed. If	N15 2	Pilot voltage (PV) to pilot gas valve.
	water level condition is satisfied and the reset switch is activated
	then N6 LED will turn off.
N7	Boiler pressure condition satisfied and reset switch activated.	N16	Ignition module main voltage (MV) to low water level
			contacts (LLCO) on water board.
N8 1	Boiler High pressure condition exists (N3 LED ON) or previously	N17	Low water level satisfied (LLCO) and main voltage (MV)
	existed. If boiler pressure condition is satisfied and the reset switch		from ignition module is supplied to main gas valve.
	is activated then N8 led will turn off.
N9	Cycling pressure switch CLOSED “call for heat”.

NOTES: 1. At initial power on, N6 & N8 led’s will be ON until conditions are satisfied and reset switch is activated.

2. Board level timing circuit energized and powers pilot gas valve for approximately 15 seconds then de-energizes.

Page 43 of 68 F24700 (October 2001)