Lochinvar 399, 999 - 750, CF-CH(E)-i&s-08 service manual Troubleshooting Guide

Hydronic Heating Boilers and Domestic Water Heaters

TROUBLESHOOTING GUIDE

399,999 - 750,000 Btu/hr Models

Step 1

Does the power switch	NO	Check the switch for proper
		operation. Check the line voltage.
provide power to the unit?

Step 2

YES
		Is there 24VAC at B2		NO
Combustion	NO	on the terminal strip?
air blower
comes on.			Check the flow switch
			Tekmar pins #15 and
		YES	for 24VAC.

	Check all safety limit
	devices, all connectors
	behind the control panel
	and voltage from the
	transformer to B2.
and	Exchange ignition
#16	module.

Step 3

YES

NO

Check 24VAC at TH (orange wire) on the ignition module.

YES

		Check staging
	NO	relay (S2). Is
		there 120VAC on
Does F2 on ignition module		the red wire to the
	YES	fan?
have 120VAC?
		YES	NO

Prepurge light comes on.		NO	Check air pressure
Status light does not			switch 24VAC on tan
blink 1 flash continuous.			wire (N.O.).
			YES	NO
YES
	24VAC at PS (tan wire) at ignition			Check air pressure
				switch for correct
	module and/or connector plug for
				pressures.
	proving relay secure.
Step 4
Trial for ignition completes					Is air switch
		Check amp draw		YES	bouncing?
and gas valve(s) opens. Does	NO
		for 3.1 amps.
not go into flame failure.

	Replace fan.	Replace
		relay.
	Replace air pressure
YES	switch.
NO	Correct air settings.
	May have to clean
	burners/heat
YES	exchanger.

NO

Step 5

YES

Replace igniter if less than 2.75 amps.

Unit is running.	NO	Gas valve(s) stays open	YES	Is the flame sense signal to the
		and is getting 24VAC.
				ignition module 5uA dc or greater?

NO

Is 24VAC present at main unit connector (3x3 amp plug) red wire?

NO

Check ignition module pin #05 (replace RLY2402 if no voltage).

NO

YES Replace gas valve.

Check inlet gas pressure both static and dynamic. Check manifold pressure. Check draft. Check air pressure.

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