Janitrol natural gas furnace

dmh1263

Premium Member
Joined
Feb 27, 2008
Messages
32
Location
Wisconsin
Hey, I have a issue with my furnace..Occasionally, when the thermostat is asking for heat, the electronic ignitor will spark and spark and spark, but no ignition. other times it will light almost instantly. What is the procedure for correcting this?? Thanks in advance..
 

Icehouse

HVAC Tech
Joined
Nov 14, 2008
Messages
387
Location
Middle Island ,LI, NY

Icehouse

HVAC Tech
Joined
Nov 14, 2008
Messages
387
Location
Middle Island ,LI, NY
[FONT=trebuchet ms,arial,helvetica]We are dedicated to helping you solve your heating & air conditioning problems! [/FONT]


[FONT=trebuchet ms,arial,helvetica]Problem: Your furnace will not ignite the gas to produce heat for your home. When a furnace has a bad ignitor what I see most of the time is the following sequence of operation:


[FONT=trebuchet ms,arial,helvetica]1. Thermostat calls for heat.[/FONT]

[FONT=trebuchet ms,arial,helvetica]2. Draft inducer motor starts.[/FONT]

[FONT=trebuchet ms,arial,helvetica]3. Pressure switch attached by a small plastic or rubber tube senses the negative pressure produced by the draft inducer and closes the circuit. Please make sure that you check your draft inducer to make sure the opening where the tube attaches from the pressure switch is open. I have seen many of these holes get stopped up so bad that you have to drill them out with a small drill bit. Take the tube off the pressure switch end. Blow into the tube. If you can not get any air through the tube then the draft inducer hole is stopped up. Drill it out with a small drill bit to repair this problem. If you have a 92% condensing furnace that produces water in the winter time, please check to make sure the drain lines are open. A stopped up drain line will cause the pressure switch not to close. Thus, the ignitor will not glow, if the pressure switch does not close. I use a wet vacuum many times to unstop the drains on condensing furnaces. Below we have some pictures of a draft inducer and pressure switches.[/FONT]


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[FONT=trebuchet ms,arial,helvetica]Above Goodman Janitrol Draft Inducer: Above Goodman Flame Sensor:[/FONT]


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[FONT=trebuchet ms,arial,helvetica]Above are pictures of two different types of pressure switches.[/FONT]
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[FONT=trebuchet ms,arial,helvetica]4. Draft inducer runs for 30 seconds to a minute before you hear a gas hissing sound. The ignitor did not glow, the flame sensor (a small metal probe about 1/8" in diameter, with a white porcelain base) does not sense the flame, so after 8 to 10 seconds the hissing sounds stops with no ignition of gas to heat your home. Your furnace shuts down and goes into a lock out condition until you turn your power switch back off and on again. [/FONT]

[FONT=trebuchet ms,arial,helvetica]Solution: Sorry, but you need to purchase and install a new ignitor.[/FONT]

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[FONT=trebuchet ms,arial,helvetica]Below we have a picture of the Ignitor that many Janitrol furnaces have installed in them, with an opportunity for you to purchase.[/FONT]


[FONT=trebuchet ms,arial,helvetica]Below is a scanned picture of various Ignitor Ceramic Block Styles & Terminal Block Styles. Hope this will help you match up your furnace with the correct ignitor. If you have a Janitrol or Goodman furnace, then the ignitor pictured below should be the ignitor you need to purchase for replacement. Thank You![/FONT]

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dmh1263

Premium Member
Joined
Feb 27, 2008
Messages
32
Location
Wisconsin
Thanks Mr. Icehouse..Are you describing a hot surface ignition furnace in your replies? My furnace is 1990 vintage, it has a spark ignitor, not hot surface.when I said that it sparks and sparks, it sparks for at least 30 seconds before it locks out. Does this info change your thinking as far as a solution? Again, it is an intermittant non-ignition. Thanks again!
 

Icehouse

HVAC Tech
Joined
Nov 14, 2008
Messages
387
Location
Middle Island ,LI, NY
Then this should help:
Troubleshooting Intermittent Ignition

Timmie McElwain Gas Heat Institute


<TABLE align=right><TBODY><TR><TD><!--Features--><CENTER> </CENTER>
</TD></TR></TBODY></TABLE>“Why won’t my pilot stay lit?” If heating service techs have heard customers ask it once, they’ve heard it a hundred times. The procedures outlined in this article are for checking out all systems that use an intermittent pilot. (Some of the checks can also be applied to direct spark ignition systems.) These are things that techs should look at as preliminary checks before proceeding with troubleshooting charts and wiring diagrams.
Many checks are visual, or done with the power off and using an ohmmeter.
In order to understand the principles behind many of the checks, it is important for technicians to understand some of the terms that are used. We therefore include a set of definitions. (See sidebar, below.)
The definitions also include two important rules for replacement of existing controls. Under the definition of “time trial for ignition,” there is a rule for replacement that says, “You can replace a module with one with a lesser time”; the “prepurge” rule says that when replacing a module, you may go to a longer time; these two rules give some flexibility when replacing controls.




CHECK IGNITION CABLE

<TABLE width="100%"><TBODY><TR><TD><TABLE width=150 align=left><TBODY><TR><TD><TABLE cellSpacing=0 cellPadding=0><TBODY><TR><TD>
</TD></TR><TR><TD>Figure 1. Continuity check from the tip of the igniter to the ground; in this case there should not be continuity.</TD></TR></TBODY></TABLE>


</TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>One of the first things to check when examining a unit’s ignition operation is the condition of the cable itself.
Make sure it’s not touching any metal surfaces.

Make sure it’s no more than 36 in. long.

Make sure the connections are clean and tight. The “kanthal” sensing/spark rod should be cleaned with a soft, clean emery cloth.

Check visually to make sure there are no cracks or breaks in the ceramic; that the igniter cable is not dried out or cracked; and that the boot is in good condition. If there is a white, powdery substance on the cable that is the result of ignition cable “outgassing,” replace the cable.

The ignition cable has electrical continuity, so use a continuity tester or the Ohms scale on a multimeter:
1. Check from the tip of the igniter to the connector on the module with it disconnected from the module. You should have continuity. The resistance should be about 0.1 ohm. If you do not, replace the cable.
2. Run the test lead up and down the tip, looking for increases in resistance or breaks in continuity (sign of a breakdown). If you find this, the igniter should be replaced. The cable on a single-rod system may give you a spark, but will not return a microamp signal due to a break in the cable.
3. Go from the tip of the igniter to ground — this time you should not have continuity. (See Figure 1.) If you do, it is shorted to ground at some point. This would cause a no-spark or weak-spark condition. In order to narrow down what may be grounded, either the cable or something in the module, remove the cable from the module and check from the connector end to ground; if it shows continuity, the cable is grounded. If the previous test showed continuity and this one does not, then the module is shorted.

Check for the intensity of the spark:
1. Remove the igniter cable from the module connection.
2. From the module connection to the igniter cable, an arc should jump at least a 1/2-in. gap.
3. The spark gap on most systems, from the tip of the igniter to the ground connection, is 1/8 in. If the spark will jump across ½ in. with good intensity, it should be able to jump across 1/8 in. with no trouble at all.
(Note: Hold the igniter cable with insulated pliers and slowly move the connector on the igniter cable toward the high-voltage connection on the module, with the module energized. The spark should jump across the open gap.)
Nuisance shutdowns or no operation at all can be caused by a poor ground or erratic ground (GND) connection.




IGNITION SYSTEM GROUNDING

From the ground (usually the green wire) terminal on the module, check for continuity to some portion of the boiler or furnace. It is best to check on an unpainted, clean surface.
You should have continuity. If you do not, then the system could operate erratically or not at all.
It may be necessary to establish a good connection to ground by using a wire with a clamp onto the gas line or equipment chassis and connecting it to the ground terminal of the module. All connections should be clean, unpainted, and generally offer good metal-to-metal contact. When you look at the wiring diagram for the equipment, if you see a symbol showing the use of a chassis ground (Figure 2), be careful that you have a good connection.




CHECKING POLARITY

<TABLE width="100%"><TBODY><TR><TD><TABLE width=150 align=left><TBODY><TR><TD><TABLE cellSpacing=0 cellPadding=0><TBODY><TR><TD>
</TD></TR><TR><TD>Figure 2. This symbol shows the use of a chassis ground. Make sure you have a good connection.</TD></TR></TBODY></TABLE>


</TD></TR></TBODY></TABLE></TD></TR></TBODY></TABLE>This next check is the beginning of your electrical checks and is best done at the secondary of the 24-V transformer. Many transformers today have terminals on the secondary labeled “C” (for common) and “R” (for hot); this will assist you with this check. If this check indicates that in fact “R” is 24 V and “C” is 0 V, then the primary polarity is correct. If it indicates the opposite, then the primary wiring needs to be corrected.
 
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