Raypak 5042004 Heater Sequence of Operation, Ignition Module, High Limit-Manual Reset

Heater Sequence of Operation

If all limits are satisfied and there is a call for heat:

1.The heater pump is powered and begins circulat- ing water through the heat exchanger.

2.The blower is powered and goes through a 15 sec- ond prepurge beginning when air flow is proven by closure of the blower suction air pressure switch.

3.The igniter is powered, and once proven, heats up for 20 seconds.

4.The gas valve is then energized for a 4 second trial for ignition period. Trial for ignition is fixed at 50% input. The heater is allowed to modulate once flame is proven and the firing rate will adjust to match the load based on the configuration and set- tings of the temperature control or external input.

5.Once the heat demand is satisfied the gas valve will close and the blower will run a 30 second post purge. The heater pump will continue to circulate water for 0 to 10 minutes depending on the pump delay setting on the Raypak modulating tempera- ture control.

Ignition Module

When additional heat is needed, the combustion air blower starts to purge air from the combustion cham- ber for 15 seconds. On proof-o f-air flow, the air-proving switch closes and the igniter is energized. To ensure safe operation, the gas valve cannot open until the igniter is verified. The main burner is automat- ically lit when the device is powered and pre-purged. The heater performs its own safety check and opens the main valve only after the igniter is proven to be capable of ignition. The standard ignition module will attempt to light three times before locking out. To reset it, turn off power to the heater, wait 30 seconds and re- apply power.

The optional single-try ignition module will lock out after failing to light one time. To reset it, press and release the small, recessed black push button located inside of the cut-out on the lower right-hand corner of the ignition module case. Turning off the power to the heater WILL NOT reset the ignition module.

Code		Condition
On		System OK; No faults present
Off		Possible control fault; Check power
1 Flash		Low air
2 Flashes		Flame in combustion chamber;
		No call for heat
3 Flashes		Ignition lockout
4 Flashes		Low HSI current
5 Flashes		Low 24 VAC
6 Flashes		Internal fault; Replace control
		Table U: Ignition Module
	Diagnostic LED Flash Codes

High Limit—Manual Reset

This heater is equipped with a fixed setting manual re- set high limit temperature device as standard or it may have an optional adjustable setting manual reset high temperature device.

The fixed setting manual reset high limit is located on the In/Out header of the heat exchanger on the right side of the heater (accessible through the front door for reset as necessary).

The optional adjustable manual reset high limit is lo- cated inside the heater junction box. Push the reset button and adjust the setting to approx. 40°F (20°C) above desired outlet temperature.

Fig. 38: Ignition Module 37 Fig. 39: High Limit (Manual Reset)