Fye on my Foul-Functioning FUBAR Furnace!

[toxcrusadr]

We have a 1989 York Stellar Plus 90+% efficient gas furnace. It has a separate combustion air blower. It’s in pretty good shape for its age because we use the woodstove daily. A couple weeks ago it started acting funny – the startup cycle would hang up and it wouldn’t fire up. I had the guy out on a Saturday (don’t ask me what that cost - ). He said the flame sensor was dirty, cleaned it with emery cloth and it started right up. 2 minutes with sandpaper. Dammit. Anyway now it’s doing it again.

The startup cycle is as follows:

Combustion air fan (vent fan) on
Hot surface igniter glows
Flame comes on
Big blower starts up
Igniter turns off

There are interlocks, pressure switches etc. at every stage of course. What I couldn't make sense of the first time around is that sometimes the igniter would glow but the gas wouldn’t start up, and other times it wouldn't glow at all, and it would just sit there with the vent fan blowing forever. But, when he cleaned it, it ran consistently for a couple weeks, so I put that little inconsistency behind me.

So it's doing it again, this time no igniter glow at all. Now that I know how to clean the sensor, I’m doing that right after work today. Possible the sensor is bad and needs to be replaced, or the furnace is not burning cleanly and it's gunked it up again.

But it seems to me that if the flame sensor is bad, the igniter would still come on, and maybe the flame should even light up. The sensor is not really doing anything until the flame comes on, right? So I wonder if there isn’t a bad pressure switch. There are two pressure switches, maybe the one that senses that the vent fan is running is not working, so it doesn’t proceed to light up the flame?

Suggestions happily considered. The wife wants me to just call it in, but I'm not confident they're going to fix it this time either, and/or might soak me again to get it done.

Should I have to pay a second service call fee since the repair didn't stick?

 

[Chip Chester]

If you have through-the-wall air supply and exhaust, they are sensitive to things being in front of, or even near the openings. I think 18" or so is the spec. If items are placed near it, or bushes have grown close to it, it may not operate due to sensors acting correctly, not incorrectly.

It's likely that all the sensors can be bypassed for testing purposes, but of course not for daily use. Do you have the manual for it? That would be crucial to informed troubleshooting.

Chip

 

[toxcrusadr]

Air inlet and outlet are free from blockages both inside and out. In fact, earlier this fall I ran a vacuum hose at least 15 ft back from the ends, almost to the first right angle in the pipe. The inlet had a small mud dauber wasp nest so that's cleaned out. I might take a peek in case a bird flew in there, or a small colony of dwarves, in the last couple weeks.

I do not have a manual, think I could get that from York? I've never looked for it. EDIT; I have the owner's manual, probably has a schematic, what I mean was I don't have any kind of service manual.

 

[devnull]

The apartment I had in WI had a gas furnace that did this exact same thing. As I recall, there was some sort of blockage in the gas line feeding the furnace.

It would cycle over and over and over, just like you mention.

Hope this helps.

John

 

[SolderIron]

I was studying up on one before. I recall it is a few switches that must be closed electrically for it to work. You may have to chase it down without a schematic on the switches and see who is open. With a manul at least you know how many there are. Without, follow the wires from the contro board. I would try very hard to find one on the web before I do anything.

 

[SolderIron]

The apartment I had in WI had a gas furnace that did this exact same thing. As I recall, there was some sort of blockage in the gas line feeding the furnace.

It would cycle over and over and over, just like you mention.

Hope this helps.

John

Check gas pressure witha water column meter.

 

[Erik Tracy]

It's a clinkerrrr!!!!

 

[fredcohiba]

Does the main board show a code, LEDs blinking? Mine did the same thing and it was the flame sensor. Got that off the LED code.

 

[Fisherdude]

I apologize in advance for the hijack, but at a quarter century old, you need to just replace it. You will not believe how much your heating and AC bills will go down.

 

[cloudchaos]

I had a brand new furnace do the same thing there is a little relay box that starts the igniter I would tap that and it would kick on I think the part was something like $20 or $30.

 

[Blast]

I apologize in advance for the hijack, but at a quarter century old, you need to just replace it. You will not believe how much your heating and AC bills will go down.

I'm going to have to go here, also. I just had similar problems a couple years ago and spent repair money that I should have just thrown at a new one, instead.

 

[Ed in Tx]

I had the guy out on a Saturday (don’t ask me what that cost - ). He said the flame sensor was dirty, cleaned it with emery cloth and it started right up. 2 minutes with sandpaper. Dammit. Anyway now it’s doing it again....Should I have to pay a second service call fee since the repair didn't stick?

I don't think you should have to pay for a second service call, only the right part to fix it this time since it's been just a few weeks since his first attempt.

The startup cycle is as follows:

Combustion air fan (vent fan) on
Hot surface igniter glows
Flame comes on
Big blower starts up
Igniter turns off

Exactly the sequence mine does, so I will be watching. I've wondered how long the electrolytic caps and relays on the control board will last. Anyway you need to get it fixed soon in the next couple of days, a major cold front's coming.

 

[KingBubba]

I had a York gas furnace and my problem was ants in the igniter unit. You could hear the cycle for the igniter to strike but it never would.

 

[whitey]

I've got a 96% some thing or other....you know the guy who wears the overalls. Any who, it keep coming on and off rapidly and I turned out to be a blocked line that drained condensation from the furnace. Cleaned the line and everything is great.

Sent from my Nexus 4 using Tapatalk 4

 

[toxcrusadr]

"The most feared furnace fighter in the tri-state area!" :thmbsp:

Thanks for all the responses. The guy came yesterday while I was out of town on a road trip. Of course, it worked PERFECTLY while he was there so he could not find the cause. He did some checking - condensate drain is OK. He told us to leave it powered on if it fails (even though the fan will just run and run) so he can come back and diagnose it. I suspect it's a failing pressure switch, or the relay/control board.
Mrs. Tox, bless her heart, let him replace the ignitor - which was WORKING - just because it 'looked old'. Did we keep the working spare then, in case it fails some cold winter night? Uh, we don't know. He was kind enough to not charge us for the service call, but only for another hour of labor (which found nothing) for $68. Plus the new ignitor. We're in for $240 now and no repair yet.

As to the age of the furnace, I believe I pointed out it gets a fraction of the use of an average furnace because of daily use of the wood stove. Our gas bill in very cold months is $60-$75, and that includes hot water, for a 2900 sf house. Just to give you an idea. It is a 90%+ efficient furnace. Just reaching the age when it needs some work, but hopefully it's not dead. If I can fix it for $300-$400, that's 10% of the cost of a new one.

 

[SolderIron]

If it doesn't fire after a try or two, I believe most model will lock in shut off mode for an hour or so or remain in shut off until reset by a power shut off. For your protection of course .

 

[SolderIron]

Jst the other day the water drain to the yard was frozen. Water level got too high in the condenser cause it to stop working. letting water drain off (2 seconds activity)fixed the problem. Wonder what the gas to water conversion ratio is.

 

[toxcrusadr]

I've been dinking around with it for a few days. It fires up sometimes, other (most) times it hangs in the vent fan stage. It does not lock out and will sit there with the vent fan running forever if you let it. So I shut off the main power cutoff switch.

Seems like it is more likely to run when it's been sitting a long time. So in the morning I can turn on the power and get it to run, heat the house up very warm while we get ready for work. Then shut it down so that vent fan doesn't try to run during the day. Woodstove has kept up along with a couple small heaters around the upstairs.

Now, I learned two days ago that one of the pressure switches (it has two, this one is for the condensate side) is not closing when the cycle hangs up. So one of two things is going on: the pressure switch is bad, or it's doing what it's supposed to and there is a different problem.

I found and ordered a pressure switch, should be here today or tomorrow. I've checked all the condensate lines and the trap. I can blow air through the trap and hear bubbles, and water poured into one of the inlet hoses does come out the bottom drain pipe into the floor drain. It's still possible there is a condensate backup somewhere, and shutting down for an extended time allows it to drain out. I don't know where this would be, everything looks clean as a whistle.

The other possibility is that the heat exchanger is rusting through, maybe there are pinholes or cracks that 'close up' when it cools down fully and that allows it to start up.

If this new switch doesn't do it, I'm calling the furnace guy back and see if I'm right. It may be time for a new furnace.

Suggestions welcome, I'm learning as I go and I'm slow at it.

 

[SolderIron]

With the new switch you will know one way or the other. I would have jumped the switch to simulate a good one then open for bad. Then pull it out for on hand checking with car hand vacuum or what ever. I am not good with patience .

 

[jdurbin1]

Just be thankful it isn't one of the defective furnaces mfd by Consolidated back in that same time period (1983 to 1992 or something like that) under a bunch of different brands. Those like to catch fire eventually and burn down your house, caused by overheating & cracking of metal parts in the burner area. York wasn't on the list of impacted brands, though.

Unfortunately, mine was. Had to rip the damn thing out and have it replaced or they were going to turn off the gas (not that I would have kept using once we knew).

John