[BDPNA]

My Ducane gas furnace is refusing to light, and it's getting COLD in here! Would love to call a tech but all are on emergency-only service for the holidays and I just can't afford that right now. Any suggestions on getting it to light, even just once would be great!

Some background - 13 year old natural gas furnace, brand new with house. A couple months ago I noticed that the pilot was kicking on and I heard flame/heat for about 2-3 seconds, then I'd hear another noticeable click and it would shut off. Main circulation fan would never start. After disconnecting some cables and troubleshooting, it just sort of started working again. Fast forward to today...

The unit turns on but only the small fan in the middle, and I don't hear the honeywell ignition unit (upper center in photo) clicking or trying to fire at all now.

Last night, a friend advised that I look in the exhaust hose trap from that smaller black fan inside the unit (that t-junction down on the lower right), sure enough, sucker was full of water! I siphoned that all out of there and re-connected but still, no luck -- After that last night I did hear it attempt to fire up once again (the pilot) but now, when I turn the power back on, the inner fan runs, but I don't even hear the pilot attempting to light/click at all anymore.

Anything safe I can try to get some heat going for Christmas? I'd be most grateful.

Oh another question as well - Am I potentially doing harm to myself or the system to leave it running without the pilot lighting and heat flowing? Any gas risk by this happening? I don't smell gas but I assume it's flowing and without it being lit I'm not sure about the safety risk.

I'm not sure if this would have had any effect on why the igniter isn't even trying to start anymore, but a couple times I got lazy when I wanted to unplug a few things and shut off the unit using the red emergency shut off switch on the wall next to the unit. I've got it back on now, and am using the breaker to shut off power to the unit now when I am messing with it, but is it possible I have to reset something elsewhere since I had used that red emergency shutoff switch? Or a particular order I need to power/switch stuff back on? It's peculiar because yesterday, the Honeywell auto-ignite was at least trying to fire from the sound of it, today, it's not even trying at all.

Any help during this holiday weekend would be most appreciated!!!

B.

 

[yuri]

1) No danger and gas flowing when the pilot does not lite, there is a flame sensor to stop it. No harm by using that red wall switch

2) Shut off the power and CAREFULLY unplug and replug in those 2 wire connectors on the gas valve. One is for the igniter and the other supplies power to the valve. That gas valve had a bad history of failures and may be the problem. There may be a red led on the circuit board which gives you an error code when the problem happens. The code is on the back of one of the furnace doors and may be the lower ones.

3) About a dozen problems can occur to cause your situation and you may really need an experienced Pro to fix it. Not something I can talk you thru and you need special tools to check the pressure switch etc.

 

[BDPNA]

Yuri,

Thanks so much for the response. I agree this is a tough one to troubleshoot via internet. From what I am reading it could be a million different things and it's one of those "you have to be there" situations for a tech. I have no problem using a tech, it's just that they're all on vacation through Wednesday so I'm sort of stuck this time, so I appreciate the troubleshooting advice sincerely.

If you mean the two connectors that are going into the beige Honeywell box at the top there (the one with the purple and yellow wires, and the other with the light blue wires), I have carefully unplugged and reseated those wires a few times now. I have also tried toggling the on-off switch that is on that beige Honeywell box as well.

If you meant different wiring, though, of course let me know. I don't seem to recall a red error led but i'll check again.

Thanks for letting me know it was at least safe to use the wall switch and that I'm not doing damage letting the unit run without the pilot lighting. The last time this happened I had to sometimes let it run 5 minutes or so before the "click" started and I heard the gas light up.

The big confusion for me today is that yesterday, it would at least pretty regularly attempt (and briefly ignite) the gas, before shutting it down. Since I cleared the water backup out of the white pipe junction at the floor there, it hasn't tried to even fire back up once.

 

[jagans]

Thats because the trap is supposed to have water in it. Its a trap. Without water, your pressure switch is not closing due to no drop in air pressure. Turn off red switch. fill the trap. Carefully pull off, clean and tighten if necessary all spade connectors everywhere. Loosen (Dont Remove) screws on main control board where wires attach one at a time clean and put back, CRC QD electronic cleaner is great here, and usually available a wally world spray and retighten wires. Try all this then turn on switch and have somebody else turn up stat while you look through that site glass there. If the same thing happens, come back and tell us exactly what happened. Turn off lights while you look and listen for clicks and other indicators, and when they occur. Then come back and tell us what you observed. Yuri is correct, of course, but you sound stuck, so we will try to help till you can call in a pro for a complete check up.

 

[BDPNA]

Thats because the trap is supposed to have water in it. Its a trap. Without water, your pressure switch is not closing due to no drop in air pressure. Turn off red switch. fill the trap. Carefully pull off, clean and tighten if necessary all spade connectors everywhere. Loosen (Dont Remove) screws on main control board where wires attach one at a time clean and put back, CRC QD electronic cleaner is great here, and usually available a wally world spray and retighten wires. Try all this then turn on switch and have somebody else turn up stat while you look through that site glass there. If the same thing happens, come back and tell us exactly what happened. Turn off lights while you look and listen for clicks and other indicators, and when they occur. Then come back and tell us what you observed. Yuri is correct, of course, but you sound stuck, so we will try to help till you can call in a pro for a complete check up.

Thank you jagans, you gave me a lot to try here. I already had some of that cleaner so that was easy, removing and tightening the wires in that lower area there.

I also can control my thermostat via phone so can shut it on/off easily right from the unit. Though if I leave it set to "heat" and turn the red switch on, that should have the same effect, right?

I refilled the trap with water and it's at least trying to fire again now. I watched through the window...Heard the first click and then a metal plate inside there glowed red hot, then the gas kicked on and I saw flame for about 3 seconds until a louder click and it cut off.

I was able to take a photo of inside the viewfinder and may even be able to get a video of what happens when it fires and kicks right off, though I'm not sure that will tell you anything.

I have the filter out of it for now, that wouldn't case it to kick off would it? Running it without an air filter?

So, basically, what happens is:

1. Red switch on.
2. Turn themostat on to heat mode via remote on phone.
3. Black fan turns on immediately.
4. About 1-2 minutes later, a single click is heard.
4. Inside viewfinder, plate glows red.
5. Gas begins to flow and flames seen/heard.
6. 3 seconds later, 2-3 clicks and gas/flames stop.

 

[jagans]

Sounds like a dirty flame sensor. Yuri posted a picture of what it looks like on the post that has Nordyne in it.

Are all of your burners lit off and burning a nice blue controlled jet? If so, clean that flame sensor that looks like a finishing nail with steel wool or emery. Use a Brillo pad in a pinch. Re-install and hook up after spraying the connection with that cleaner and come back let us know what happens. Make sure that plug is fully seated.

Im amazed you did all that so fast!

 

[BDPNA]

Hey, a man in desperate need of heat will do anything...Though I am stuck with dinner plans so I might have to quit in a bit. I actually never knew all you could see through that viewfinder in the dark. Very cool. I tried it one more time, turned off the lights and watched.

It takes about 1 minute before the Honeywell box (igniter? - sorry not up on all the terminology) clicks and then I see things light up red/blue in there, then the gas, and yep, I see a steady stream of about 3 or 4 rows of blue flame (coooool) in there flowing nicely, before suddenly a few more clicks (I can't be certain where these are coming from) and it cuts off the gas.

I'll go look up that post with Nordyne so I can make sure I have the right part -- Is there any trick or danger in removing it? Electric off, obviously, does the gas need shut off or is turning off the red switch enough? Just want to make sure I am extra careful.

 

[BDPNA]

Okay, I see the part, but have no idea where to look for it in my unit, do I need to take more apart or (gasp) go up into the windowed area where the flames are?

Just want to make sure I am looking/working in the right spot, first of all, and second, doing it safely (can you tell I hate working on gas appliances)? Makes me nervous.

I did smell a quick whiff of gas I think when it flamed on but I suppose that is normal.

Thanks.

 

[jagans]

Nothing wrong with being careful. No you do not have to turn off the gas unless it would make you feel better. Just make sure that the flame sensor is in the flame patch when you put it back in. It should auto-locate by the screw and an alignment pin. Dont forget to spray and check the plug for soundness, and proper insulation. (No bare wire grounding etc.)

 

[BDPNA]

Okay, so I am correct in assuming I need to take apart the area behind the window to find this part? Is that where it is? Just want to make sure I am looking in the right place.

Sorry for all the dumb questions.

 

[yuri]

NO you don't that easily with that unit. The flame sensor is very tiny and not like a conventional one in my pic and is built into the pilot burner assembly and VERY difficult to get at on that unit. VERY easy to break the HSI hot surface igniter (glowing red part) when working with it. That is a very difficult job to do so you may get in over your head and break something but if you want to try go ahead. Check your venting outside for obstructions. Does it have a seperate intake and exhaust pipe outside or a round donut shaped one piece concentric unit? Either way check them carefully for blockage and if you have the concentric then you need to stick your fingers behind it and check for debris, spiders webs.

 

[jagans]

If thats where the burners are, Thats where the flame sensor is. Do yourself a favor. Take a break and your model number and google that model number. Give it to us too. We may be able to look at a service manual and see where the flame sensor is. Your picture cuts off the top of the furnace but it looks like you need to back out those 7/16 or 1/2 inch tapping bolts to get that cover off.

 

[BDPNA]

If it's as difficult as Yuri suggests for my unit, and that's most likely the issue, it sounds like I am too in over my head unfortunately. I will check for obstructions outside but I don't expect any issues, this is a residential home and the vents go right out on the lower level, I can easily access them. There are 2 pvc pipes that go out from the unit and out the back of the house.

 

[jagans]

See I told you Yuri would know. My unit is a Carrier and really easy to get to. I guess good engineering costs. Do what Yuri tells you from here on out. Im sure he has forgotten more than I will ever know about furnaces.

 

[yuri]

Unfortunately that unit is difficult to work on and I usually just replace the entire pilot assembly with the sensor and igniter as it gets rusty and corroded and it will take forever here to tell you what else goes on. Sounds like somethng is choking the flame/burner or tripping the pressure switches and that could be venting related or a dozen other problems.

 

[yuri]

See I told you Yuri would know. My unit is a Carrier and really easy to get to. I guess good engineering costs. Do what Yuri tells you from here on out. Im sure he has forgotten more than I will ever know about furnaces.

Done my share of roofing work, dealing with leaky flat roofs on a hospital etc and hated it, we had a fabric roof on the Convention Centre I used to work at . Can't imagine how long that will last compared to a conventional roof.

 

[jagans]

Yeah Yuri,

Roofing is kind of a Black Hole. (Pun Intended) Not sure what a "Fabric" roof is, Maybe a reinforced single Ply. They will be OK for 20 or so years if it is Fibertite or another good membrane.

The thing with commercial roofing is that once you bag a couple of decent sized projects $500,000.00+ its hard to walk away. :whistling2:

Have a Great Christmas and NY

 

[yuri]

I think the tech guy said it was good for 20 yrs but what do you do after that. Rip it off. Didn't seem very durable to me.

 

[jagans]

Well it sure as heck isnt 16, or 20 oz. Copper, DAS-A-FA-SHOE!

Of course with all the acid rain the US sends up to Canada they would have been better off with LCC. :huh:

 

[BDPNA]

Knowing that you just replace the whole thing, Yuri, says a lot. I guess I got an extra 2 months out of it somehow but the timing just was the unfortunate part here, having a cold house for Christmas is a bummer but what can ya do. I really appreciate all that you guys did to try and help, thank you so much.

I may take one more panoramic shot so you can see the entire system and the outtakes but most likely this 13 year old furance just needs a part or two.