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Effective: August 2015

4

F-35-63

TROUBLESHOOTING

Note:

During a fault condition, the LED will flash on for 
1/4 second and off for 1/4 second as needed to 
indicate the fault code. The code will repeat every 
3 seconds. Removing power from the control will 
clear the fault code.

Internal Control Failure

If the control detects a software or hardware error, all outputs 
are turned off and the LED displays a Steady On condition. If this 
condition persists after an attempt to restart, then the control 
must be replaced.

Proper Electrode Location

Proper location of electrode assembly is important for optimum 
system performance. The electrode assembly should be located 
so that the tips are inside the flame envelope and about 1/2-inch 
(1.2 cm) above the base of the flame as shown:

Notes:

Ceramic insulators must not be in or close to the flame.

Electrode assemblies must not be adjusted or 
disassembled. Electrodes are NOT field adjustable.

Electrodes should have a gap spacing of 0.125± 0.031 
in (3.12± 0.81 mm), unless otherwise specified by the 
appliance manufacturer. If spacing is not correct, the 
assembly must be replaced.

Exceeding temperature limits can cause nuisance 
lockouts and premature electrode failure.

Electrodes must be located where they are not exposed 
during normal operation.

Flame Current Measurement

Flame current is the current that passes through the flame from    
sensor to ground. To measure flame current, connect a True 
RMS or analog DC micro-ammeter to the FC+ and FC- terminals. 
Readings should be 1.0 µ

A

 DC or higher. If the meter reads 

negative or below "0" on scale, meter leads are reversed. Re-
connect leads with proper polarity.

Alternately, a Digital Voltmeter may be used to measure DC 
voltage between FC+ and FC- terminals. Each micro-amp of 
flame current produces 1.0 VDC. For example, 2.6 VDC equates 
to 2.6 µ

A

.

A good burner ground that matches the control ground is critical 
for reliable flame sensing.

Troubleshooting Guide

Symptom

Recommended Actions

1. Control does not start

A. Miswired
B. 24 VAC transformer fault
C. Fuse circuit breaker fault
D. Faulty control, check LED 

for fault codes

2. Thermostat on - no spark

A. Miswired
B. Faulty thermostat, no 

voltage at thermostat 
terminal TH/W

C. Faulty control, check LED 

for fault codes

3. Valve on - no spark during 
TFI

A. Shorted electrode - 

establish 1/8-inch gap

B. Check high voltage cable
C. Miswired

4. Spark on - valve off

A. Valve coil open
B. Valve wire disconnected
C. Faulty control, check 

voltage at gas valve 
terminals PV1 or MV1 and 
V2

5. Flame okay during TFI - no 

flame sense after TFI

A. Check electrode position
B. Check high voltage wire
C. Poor ground at burner
D. Poor flame, check flame 

current

Fault Conditions

LED Indication

Fault Mode

Steady On

Internal Control Failure

2 Flashes

Pilot flame without call for heat

3 Flashes

Ignition Lockout

Summary of Contents for 35-63

Page 1: ... MH8817 Design certified to ANSI Z21 20 CAN CSA C22 2 No 199 M89 CE Approved to EN 298 2003 Code Compliant to AS 4625 2008 AS 4622 2004 Input Power Control 18 30 VAC 50 60Hz Class 2 Transformer Input Current 300 mA 24 VAC with main and pilot gas valve relays energized control only Main Gas Valve 2 0A max continuous Pilot Gas Valve 2 0A max continuous Operating Temperature 40 F to 176 F 40 C to 80 ...

Page 2: ... additional ignition trials before de energizing the pilot valve and entering lockout The LED will indicate the fault code for ignition lockout FLAME FAILURE RE IGNITION MODE If the established pilot flame signal is lost while the burner is operating the control will respond within 0 8 seconds by de energizing the main gas valve and energizing the H V spark for the TFI period in an attempt to reli...

Page 3: ...oper and dangerous operation A functional checkout of a replacement control should always be performed WARNING This product uses voltages of shock hazard potential Wiring and initial operation must be performed by a qualified service technician WARNING Operation outside specifications could result in failure of the Fenwal product and other equipment with potential for injury to people and property...

Page 4: ...urement Flame current is the current that passes through the flame from sensor to ground To measure flame current connect a True RMS or analog DC micro ammeter to the FC and FC terminals Readings should be 1 0 µA DC or higher If the meter reads negative or below 0 on scale meter leads are reversed Re connect leads with proper polarity Alternately a Digital Voltmeter may be used to measure DC volta...

Page 5: ...X 3 750 250 3 250 010 5 000 010 2 250 250 164 010 DIA 450 MAX 015 031 062 4 MOUNTING GND TH W V1 P1 IND V1 V2 S1 475 HOLES 500 MAX 2 000 MAX 475 2 MOUNTING HOLES 187 010 DIA 2 250 S1 V2 IND V1 V1 P1 TH W 5 688 5 000 010 359 3 250 010 344 1 750 MAX GND DS1 FC FC 3 375 010 1 125 063 3 375 010 3 968 2 MOUNTING 234 010 DIA HOLES Note All dimensions are in inches ...

Page 6: ... of Flame 2 Standard CE Approved Model 3 Special CE Approved Model 5 Re ignition After Loss of Flame 9 Special Configuration Pre Purge Time 0 None 1 15 Seconds 2 30 Seconds 3 45 Seconds 4 4 Minutes Number of Ignition Trials Flame Sense Method and Lockout Reset Method 0 Single Try Local Sense 1 Single Try Remote Sense 2 Single Try Local Sense 3 Single Try Remote Sense 5 Three Tries Local Sense 6 Th...

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