Furnace burner ignites and stops every 5 secons


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Old 03-29-10, 07:50 AM
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Furnace burner ignites and stops every 5 secons

My 10 year old comformaker furnace ignites for few seconds and there is click sound and goes off. This cycle repeats continuously.
I tried to clean the flame sensor. I am not sure which part should I clean it.
The sensor looks like the
HONEYWELL Q345A1065 FLAME RECTIFICATION SENSOR 88882 - eBay (item 200404907136 end time Apr-10-10 11:11:30 PDT)

Is it easy to take the parts out by unscrewing the gas connection pipe and the electric wire?

Advance thanks for your help!
 
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Old 03-29-10, 09:25 AM
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The flame sensor wire goes back to the controls where the lone wire plugs in and should say Flame Sense, or something like that.

Not sure if your flame sense capability is at that pilot or if you have another flame sense rod at the right side burner. If you have a separate flame sense rod, you would see another wire head over to right side of the burners and also see a wire between it and the ignition module where on the module would say Flame Sense(or to that effect) on it. If it does not say that, but only has the word Ground and Burner ground, then likely you only have the pilot assembly sensing the flame.

If you do not have a separate flame sense rod, then it is done either through the spark electrode or a separate green? burner ground wire, that goes back to the ignition control module. If the former, polish clean the electrode rod. If the latter, make sure such metal parts that the flame can hit, like the flame hood area, is polished up and that the wire connected to the burner assembly is making good ground.

Some furnaces are easier to remove the pilot burner assembly than others. It is a see and do project that should be straight forward, if you are at all mechanically inclined. You unscrew anything you have to, to be able to remove it. Kind of like with cars. Some cars you can remove an alternatior in a few minutes. Others you have to dismantle half the car first.
 

Last edited by ecman51; 03-29-10 at 09:44 AM.
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Old 03-29-10, 10:09 AM
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If you have that Honeywell pilot burner, there is no separate flame sensor. The rod in the center is the high voltage spark cable, and the cage behind and above the spark electrode functions as the flame sensor.

Frankly, I've never seen that Honeywell pilot quit working because it needs the cage cleaned, although anything is possible I suppose.

I suppose it might be worthwhile to leave the pilot burner in place and clean the cage with some fine sandpaper or a wire brush.

You really need to measure the DC microamps flowing from ground to the ignition module to find out what is going on.

Do you have a multimeter that measures down to 1/2 microamp or so? If so, what is the model of the Honeywell ignition module?

(note: 1000 microamps = 1 millamp.)
 
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Old 03-29-10, 12:09 PM
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Thank you both for your answer.

I tried to cleanup the metal frame (with split) that is just above the spark without removing from the unit. Still the same issue.

The following are the links to the video and photo of the furnace issue

YouTube - Furnace Flame sensor issue
Picasa Web Albums - FurnaceIssue


I am scared to remove the blue wire. Do I have to pull the blue wire? I don't know whether it will damage anything?
 
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Old 03-29-10, 03:44 PM
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Blue Wire

You can trace the blue wire to the other end & unplug it there. If those photos are of your furnace, somebody has used steel wool on the pilot burner. A major mistake. Steel wool can easily get into the pilot orifice & partially or completely block it. It can also cause the microamp current S/P spoke of to be grounded out & not get to where it needs to be.
 
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Old 03-29-10, 04:06 PM
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From your video, the spark turns on properly. There is a notable delay before the pilot lights the first time, but it lights promptly on successive trials.

Once the pilot lights, the spark shuts off properly, indicating that the pilot flame has been correctly sensed.

But then the pilot burner shuts off, rather than staying lit and the main burners lighting. That shouldn't happen unless the 24 VAC to power the ignition module is being lost, which seems unlikely.

After that, it repeats this sequence several times except that the pilot burner lights promptly on these later trials.

I would call that erratic operation of a defective ignition module.

Replace the module.
 
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Old 03-29-10, 06:40 PM
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Good Point

S/P is correct in his saying the spark shuts off as would be normal having sensed a pilot flame. Once pilot is sensed the ignition control should energize the MV terminal. It seems your control is not doing that. My question is "why is the pilot going out?"
Once ignited the pilot should stay on, should it not S/P? Unless the control is loosing 24v? You know WAY more 'bout this gas stuff then I. Just asking questions in hopes of learning more.
 
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Old 03-29-10, 07:48 PM
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Oops. Yes,It is my furnace. I have used the steel wool.

How much would it cost for the module? Can I do it myself or call technician?
 
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Old 03-29-10, 08:10 PM
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Yes, the pilot should stay lit and once the flame is sensed (VERY rapidly with this module) the pilot should remain lit and the main burner gas turn on.

There are a variety of things you could check, from verifying that the gas pressure remains good when the main burner switches on, for example --- that kind of thing would cause this symptom.

But I don't know that a DIYer is going to have the skills for that.
 
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Old 03-30-10, 04:58 PM
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Testing

There are some things a DIYer can check if you have a volt meter & know how to use it properly. But I'm not so sure about messing with the gas side. A "small" mistake could lead to some no so small, no so good, results.

I found a Honeywell S8610U-3009 ignition module (replacement for the S8600M) online here:
Patriot Supply - S8610U3009
 
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Old 03-30-10, 06:33 PM
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I had to put one in days ago. Paid $115 for it at one of our several supply houses. Symptom of the one I took out was - spark, but no pilot, and of course no burner. I first tested and found 24 volts at the ignition module with a call for heat. (But that was already expected since I had spark, and since there is no other source for line voltage coming into that ignition control module).

Then, after making sure the gas valve was on, and that the pilot was burning on the gas water heater, I tested voltage at the 3 wires on the gas valve (PV, MV, and C),and my digital meter went wild, with blinking of 4 digits, then I got a 120 volt read (on the 24 volt line!!) and 87 volts a few seconds later! So then I disconnected all 3 wires from gas valve to test again,........testing the wires themsleves during my furnace reset call for heat (especially between PV and C), to eliminate a short in the gas valve solenoid which then maybe could have been bleeding off the current from my meter. Nope. Same goofball readings. Then I knew it HAD TO be the module.

Then after I installed the new Honeywell S8610U, I got a steady 28 volts from PV-C and she lit right up.

Note that you have to read the thick booklet to see how to convert from your current ignition control module to the universal S1886U. You want to read about the 2 dip switch settings. You also want to read about the jumper wire that is over on the right side of the new module. The one wire that might be the trickiest for someone that does not know where to hook it up is the 24 volt wire that goes through the THermostat and activates the 24 volt safety circuit. That one gets hooked to the spade marked TH.

On mine, I had the 3 gas valve wires to hook up and those are perfectly identified. Then the burner ground wire, and that is identified as such, also. And the last wire was that stat/safety circuit wire and that one had to be decided between going to the terminal marked "ground" or to TH. TH it was.

I did not require to put anything on the "ground" terminal, per their drawing, for my application. But for the fun of it, I cracked open the cover of the old module to see if the brass ferrules, where the mounting screws went through, were attached to the circuit board, and completing a ground circuit through the circuit board = no. So I felt better.
 
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Old 03-31-10, 03:40 PM
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Revision to post #11!

Went to that house today(vacant right now) to be certain that what I said yesterday was correct. It wasn't. Here is the correct hookups I required:

MV, MV/PV, PV are the 3 wires that go to the gas valve.

GND is the ground wire from the pilot assembly and is also grounded to the furnace by virtue of how the pilot assembly is screwed to it.

24V(gnd) is the 24 volt safety circuit.

24V is not used for my applciation.

TH-W has a white wire that goes from it to the C(common) terminal on the furnace's 24 volt power strip that the thermostat wires hook to.
 
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Old 04-01-10, 08:44 PM
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I am not good with this electrical connections. So I did not have choice but to call the service. They identified the issue is with the ignition module and replaced it.
They charged parts $290 and service call $65.

Thanks everyone for your help on this issue. Hopefully I can do it myself next time.
 
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Old 04-02-10, 02:01 PM
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Well, at least that was the problem. You didn't really get gouged, either.

You read what I paid for one. But heh, they got to make a living: Training, certification, tools, truck-repairs- tires -gas, insurance, retirement, bookkeeping/office, estimates, expediting, advertising expense etc. (and that be just for the repairman with no employees/no company building, working out of his house!) So you can't really feel bad in thinking they "cleared". $2 hundred and some dollars on you for work that maybe took them 1/2 hour, or whatever.

It might serve you well though to try to learn enough basics where you are not that intimidated by say change-out work. Albeit, this changeout is not THE most straight forward when you go from factory OEM part to some universal part that must be retrofit.
 
 

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