Honeywell Furnace -- Pilot keeps going out


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Old 01-24-10, 09:40 AM
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Question Honeywell Furnace -- Pilot keeps going out

We own an older Honeywell gas furnace. I'm not sure of the model # but i did see VR8204A 2001 and Honeywell S860D Intermittent Pilot. The furnace has been working thus far but only today it hasn't been kicking in. The thermostat appears to be working fine.

What's happening is i can hear the furnace running (photo #2 -- the cylinder unit with the black cap. sounds like fan?) and after 30 secs i can then hear a click / electric spark (?) coming from the horizontal opening in photo #4. A flame appears within there but quickly extinguishes ( < 1 sec). The entire process repeats over and over every 30 secs.



The furnace automatically handles the spark / ignition. I've attempted to clean the flame rod with steel wool (cleaning may not have been perfect as i was unable to remove the unit from the furnace). I also disconnected the RED cord from the Honeywell Intermittent Pilot box, cleaned the end, and reconnected. I was unable to remove the RED plug from the back end of the flame rod.

Thanks for any advice.
 
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Old 01-24-10, 09:49 AM
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Without being able to see the pilot flame I will offer this: clean the pilot. If the pilot flame is not burning properly, the burner will not come on or will "short cycle". Please do this and post the results. before cleaning check if there is a yellow flame. If yes the pilot needs cleaning.
 
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Old 01-24-10, 11:36 AM
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There is a metal strip that runs from the pilot base , bends around the ignitor and ends close to the pilot hood. This strip of metal is used as a ground for the ignitor and also serves as a flame sensor. This needs to be cleaned well but use caution so the assembly is not damaged. Judging by the scale in the bottom of the furnace, I would say it is past due for a professional service.
 
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Old 01-24-10, 04:33 PM
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As mbk3 suggests, cleaning the pilot burner will usually solve the problem you describe. The best way to do that is to replace the pilot orifice, but you may find it difficult to get a new part.

You can try cleaning the existing orifice. That involves removing the brass ferrule at the bottom of the pilot burner that holds the pilot tubing in place with a 7/16" wrench.

Once that's removed, the pilot orifice may drop out on it's own if you are lucky, but you might have to dig it out using a miniature screwdriver, and sometimes it's corroded in place and wont come out, which would involve replacing the pilot assembly.

If it comes out you can blow it out with compressed air and hope that is sufficient. Replacing it is recommended.

You can clean the cage and ground as suggested by skip at the same time.
 
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Old 01-25-10, 02:49 AM
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Ok i was able to remove the unit from the furnace. I cleaned it and took some photos:



I'm still unable to pull off the red plug from the back of the flame rod.
 

Last edited by quantass; 01-25-10 at 03:45 AM.
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Old 01-26-10, 10:02 PM
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Ok a furnace expert came by and had a look while i wasnt around. He claims to have cleaned the flame rod unit that i removed and placed it back in. The issue persisted. He "thinks" the issue could be with the Honewell Intermittent Pilot control box (the board?). The flamerod connects to it with a rubber hose plug. +$300 to replace. He said if it isn't that then it might be the gas valve (+$200?).

I'm not happy with all the IFs. Isn't there a conclusive way to identify what exactly is the problem without having to purchase non-refundable parts?


The technician said they were able to manually jump start the furnace.
 
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Old 01-27-10, 02:16 AM
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Did you remove the pilot tubing and replace the pilot orifice? It doesn't look like it since all your pictures show the pilot tubing in place.

That's the first thing I'd do, which very commonly solves the problem.
 
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Old 01-27-10, 03:48 AM
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No i did not. Can the orifice and tubing replacement be purchased at Home Depot? I will call around and do that very thing. Will let you know...
 
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Old 01-27-10, 08:18 AM
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No, pilot orifices aren't available at Home Depot or even the typical good hardware store. You need to shop at a furnace distributor or froma furnace repair outfit for that part.


That Honeywell Part Number 390686-5 can be seen here:

honeywell pilot orifice - Google Product Search
 
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Old 01-27-10, 11:06 AM
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Originally Posted by quantass View Post
Ok a furnace expert came by and had a look while i wasnt around. He claims to have cleaned the flame rod unit that i removed and placed it back in. The issue persisted. He "thinks" the issue could be with the Honewell Intermittent Pilot control box (the board?). The flamerod connects to it with a rubber hose plug. +$300 to replace. He said if it isn't that then it might be the gas valve (+$200?).

[B]I'm not happy with all the IFs. Isn't there a conclusive way to identify what exactly is the problem without having to purchase non-refundable parts?
[/B]

The technician said they were able to manually jump start the furnace.
I can understand your frustration with "If's", however you are there and we are here and trying to help as best we can. Several of us has many years experience, but when you are not on site it can be trying. When S/P and I mention to clean the pilot, that comes from years of seeing what happens when pilots are dirty. It is also the least expensive repair. Usually a new orifice is not required if you have the knowledge and the proper tools for cleaning. Most people do not have the cleaning tool available, so a new orifice is needed. They type of pilot you have needs the entire hood portion of the pilot area cleaned in addition to the orifice area. Have you removed the hose from the inducer to the pressure switch and cleaned inside to two hose ports? This can be done with a paper clip. Sometimes water crystalizes or spiders make nests which then slows done or prevents the pressure switch from closing properly and may cause your situation. Also check the tubing for cracks. I am wondering what "they" meant by "jump starting" the furnace? Try disconnecting the thermostat red and white wires from the furnace and then install a jumper on those two terminals at the furnace, that will determine if the thermostat may be at fault. Whew I'm tired of typing
 
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Old 01-28-10, 08:46 PM
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SOLVED

Ok we got it fixed. We worked backwards replacing the ignitor / pilot unit. No go. Then we moved back to the intermittent pilot box. Bingo. That was the problem. Furnace is working fine now.

THANK YOU everyone for all your help with this new world. All the info was greatly useful!
 
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Old 02-12-15, 09:57 PM
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found this thread from google and signed up to chime in with my experience.

my furnace setup is very similar to the OPs. I'd go and look but it really doesn't matter in my situation. in the end it was the S860D pilot module.

my furnace started acting up in the past couple of days. i'd wake up freezing as the furnace seemed to have troubles staying on after a long period of downtime.

after having a look the symptoms were somewhat random.
exhaust fan kicks on, pilot lights, burners light, blower fan turns on and everything shuts off.
exhaust fan kicks on, pilot lights, burners light, everything shuts off.
exhaust fan kicks on, pilot doesnt light and sits there clicking for a minute. cycle repeats but it lights pilot and shuts off.

like i say, somewhat random.

after mucking around with the flame sensor and the pressure sensor for hours going crazy i found it was the pilot control.

im no expert when it comes to furnaces by any means (this is my first experience working on them) but i can safely say its the pilot module.

here was my method of testing:
get baseline for pressure switch and flame switch. to test these i removed them from the 24VAC circuit and checked resistance on their terminals. for the flame switch i held a lighter below it until it clicked and when it did it opened the circuit.
for the pressure switch i removed the hose and sucked on the opening and the circuit closed (normal, it will only allow the voltage across if there is a vacuum). the flame switch is normally closed until the heat gets to it and pops it open.

despite both of these being operational, the symptoms still occured. i then cleaned the pilot, the tip of the ignitor and all surfaces (with a steel brush on the dremel). same problem. i verified the pilot pipe wasnt clogged as well.

knowing all this, i still chose to bypass the switches anyways incase they were intermittently operating.

last thing to check was the pilot module (Honeywell S860D). I didn't get my scope out to record a log of the voltages going to the gas valves or safety circuit but it was pretty obvious. manipulating the spark plug wire after it had started the furnace properly almost instantly shut it off. the plug seemed kind of loose so i coompressed it a bit for a better fit. not making sense to me how this could fix it i did it anyways and still had issues.

what ended up working was pulling the PCB from its plastic case and taping it down with a certain direction of force prevented it from shutting off the gas valve/safety circuit. im going to guess one of the 3 relays on the board is failing which is causing it to shut down the burners and restart.

not worth looking into after spending so much time on it already i'm just replacing it.

hopefully this helps someone!
 
 

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