Honeywell Y8610U Product Data page 15

STEP 3: Check spark ignition circuit. You need a short jumper wire
made from ignition cable or other heavily insulated wire.
Close the manual gas valve.
Disconnect the ignition cable at the SPARK terminal on the
module.
WARNING
When performing the following steps, do not touch
stripped end of jumper or SPARK terminal. The
ignition circuit generates over 10,000 volts and
electrical shock can result.
Energize the module and immediately touch one end of
the jumper firmly to the GND terminal on the module.
Move the free end of the jumper slowly toward the SPARK
terminal until a spark is established.
Pull the jumper slowly away from the terminal and note the
length of the gap when sparking stops. Check table below.
Arc Length
No arc or arc less Check external fuse, if provided.
than 1/8 in. (3 mm) Verify power at module input
terminal. Replace module if fuse
and power are okay.
Arc 1/8 in. (3 mm) or Voltage output is okay.
longer.
STEP 4: Check pilot and main burner lightoff.
Open the manual gas valve.
Set the thermostat to call for heat.
Watch the pilot burner during the ignition sequence to see if:
• ignition spark continues after the pilot is lit;
• pilot lights and the spark stops, but main burner does
not light.
Action
15
Y8610U INTERMITTENT PILOT RETROFIT KIT
Ensure adequate flame current as follows:
• Turn off the furnace at the circuit breaker or fuse box.
• Clean the flame rod with an emery cloth.
• Make sure the electrical connections are clean and tight.
Replace damaged wire with moisture-resistant No. 18
wire rated for continuous duty up to 105°C (221°F).
• Check for a cracked ceramic insulator, which can cause
short to ground, and replace the igniter-sensor, if
necessary.
• At the gas control, disconnect the main valve wire from
the TH or MV terminal.
• Turn on the power and set the thermostat to call for
heat. The pilot should light but the main burner remains
off because the main valve actuator is disconnected.
• Check the pilot flame. Make sure it is blue, steady, and
envelops 3/8 to 1/2 in. (10 to 13 mm) of the flame rod.
See Fig. 20 for possible flame problems and their
causes.
• If necessary, adjust the pilot flame by turning the pilot
adjustment screw on the gas control clockwise to
decrease or counterclockwise to increase the pilot
flame. Following adjustment, always replace the pilot
adjustment cover screw and tighten firmly to assure
proper gas control operation.
• Set the thermostat below the room temperature to end
the call for heat.
Recheck ignition sequence as follows:
• Reconnect the main valve wire.
• Set the thermostat to call for heat.
• Watch the ignition sequence at the burner.
• If spark still does not stop after the pilot lights, replace
the ignition module.
• If the main burner does not light or if the main burner
lights but system shuts down, check module, ground
wire, and gas control, as described in the
troubleshooting guide, Fig. 19.
68-0133—2