Furnace blows but does not heat (intermittent problem)

We have a "York Diamond 90" gas-fired furnace that was working well until today.

There seems to be something wrong with the gas flow/valve, burner, or sensor.

I can see the electronic ignition element turning white hot, then hear the gas valve click on, then see the blue gas flames light for a second or two before sputtering out. This cycle repeats itself several times until, the system "gives up" (or I guess locks out) at which point the blower just continues to blow cold air forever and no further ignition attempts are made. The blower continues to blow even if I shut off the thermostat

Interestingly, if I cycle off the power (even just for a second or two), the furnace will start up normally and ignite the burners properly. The burner will continue to fire for a *couple of minutes* before blowing out at which point it goes into the (failed) cycle of trying to relight a couple of times before finally giving up and again leaving me in the stuck state with the blower blowing cold air.

Sometimes in the cycle of trying to re-light it will burn for a few seconds before sputtering out. Also, sometimes, I hear the valve clicking on-and-off a couple of times in rapid succession.

Now the other two gas furnaces are working properly, so I don't think it is a supply problem. Also, I don't think it is a ventillation problem because it seems to burn fine for a few minutes with a nice blue flame before suddenly sputtering out.

When I opened up the bottem panel (overriding the disable switch), I noticed that after it locked up in the continuous blower position, the diagnostic LED exhibited a pattern of 8 short (red) flashes -- I believe this simply indicates that the flame is lost 5 times within a heating cycle which according to the online manual indicates either: Low gas pressure (unlikely since other two gas furnaces in the house work fine, right?) Faulty gas valve Dirty or faulty flame sensor Faulty hot surface igniter (unlikely because the flame does ignite, right?) Burner problem

Any idea what might be wrong and how to fix?

Even if this is not a DIY fix, I would like to have some idea of what the potential problems could be so that I can intelligently engage the service person and make sure that I am not being taken :)

Thanks!

Reply to
blueman3333
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I believe there may be a flame sensor. Its failure could cause the symptoms you describe.

Reply to
CJT

One interesting additional (but probably unrelated fact)... The only recent change to the system is that two days ago I installed a condensate pump since previously all the condensate was just dripping vertically down a 2-story 3/4" pvc pipe onto our crawl space floor. I connected a short length of 5/8" clear flexible tube to the end of the pvc pipe which then hangs over the basin of the condensate pump. The condensate pump seems to be pumping the water fine.

Not sure how this could be related to my problem since the water is draining by gravity into a basically open reservoir so I don't see how it can be backed up two stories to the height of the furnace. However, the timing is strangely coincidental...

Reply to
blueman

Could you have bumped an electrical connector on the controller board while installing it?

For instance, one for the flame sensor? :-)

Reply to
CJT

Bad thermostat.

Change to a digital thermostat and upgrade the wiring too.

Reply to
Oscar_Lives

Would this be consistent with the fact that initially the flame burns for a couple of minutes before shutting off?

Also, if it is a flame sensor, how difficult/advisable is it as a DIY repair? (I am very experienced in electrical, electronics & mechanical, reasonably experienced in plumbing, but have minimal experience in gas).

Reply to
blueman

Nowhere near the controller -- I was just down in the crawl space... unless somehow manipulating the pipe downstairs somehow moved the other end on the second floor bumping something electrically...

Reply to
blueman

Why exactly is it that you homemoaners think you need to "engage" the service tech? All that does is run your bill up while we waste time chit chatting on your dime. A good tech really doesnt need to hear a word from you other than, "the heat doesnt work and its down there in the basement". If he needs any more than that then he isnt much of a competent tech. If you want to fix it yourself, pull all the parts off the working furnace and start putting them on the inoperative furnace one by one till you get it. Whats the worst that can happen? Your burn yourself, you asphyxiate yourself or your family, you burn your house down or you electrocute yourself. and maybe, just maybe, you might get it right. Bubba

Reply to
Bubba

Get which part right? The burning, asphyxiation, arson, electrocution, or the part about calling someone who doesn't have to guess, actually knows where the basement is?

Reply to
Mo Hoaner

I once had similar symptoms (I have since moved).

I had a condensate pump, and it filled with "gunk" over time. I had a contractor confirm this was the problem. He removed the pump, took it outside, took a hose to it, reinstalled, and the problem resolved. Don't actually know what the failure mechanism was, but this resolved it. It happened again a year later, but I just cleaned the condensate pump again. When I moved, I left a note for the buyers, and included a description for them to rinse out the condensate pump about twice a year.

Don't know if this is the same problem as yours, but thought I'd share my story.

Reply to
Dimitrios Paskoudniakis

Minutes? I thought you said "a second or two."

It's entirely consistent with "a second or two" multiple times over a span of minutes.

I've never seen your particular furnace. It might just be dirty. Look for a little gadget with a window facing the flame and a couple of wires coming out of it. Make sure the window isn't sooty and the wires are still connected to the control board. Judge for yourself how hard it would be to change it.

Of course, it could also be the associated control board electronics. Less likely, IMHO, but possible.

Reply to
CJT

You guys just hate it when a service call is avoided, don't you.

Reply to
CJT

Actually was looking at the wrong manual before. According to the right manual for my model, the two possibilities are: 1. Low gas pressure 2. Faulty gas valve

Does that make sense and sound right relative to the symptoms I have described?

Reply to
blueman

Bubba is big enuf to answer for himself, but actually us guys LOVE to be called in after a homeowner has f***ed things up royally.

go right ahead and buy all the parts you want and install them yourself. try getting a warranty on those parts, especially after you f*ck them up installing them yourself.

see, this particular ho cant get his story straight. first it fires for a few seconds then dies, then he says it runs for several mins then dies. which is it?

Personally I think the best part is the f***ed up design of the York piece of shit furnace, running the blower 24/7 non stop when the system goes into fault mode. A real genius at work there.

Reply to
gofish

It initially burns for maybe 2-3 minutes without interruption. Then it starts cycling with each subsequent flame lasting typically for 1-2 seconds or often even less (though sometimes I have seen it last as long as 10 seconds).

Reply to
blueman

I suppose anything is possible, but given that the burner starts, neither seems terribly likely (to me).

Reply to
CJT

What a waste of response. If you don't want to help, then don't respond to posts. If you hate engaging with customers, then you shouldn't be in the SERVICE business.

The good service techs I know really appreciate it when a knowledgeable homeowner has done his/her homework. At a minimum it saves some diagnosis time. It also very often saves a return trip back for parts.

Engage your brain for a second and just think -- if I can diagnose the problem or at least narrow it down in advance, then the service tech may be able to actually bring the right replacement part on the first visit. This save me and the tech time and money.

Also, at least in the world I live in, there are many service people who are only too happy to swap out parts until they get it right rather than spending time on diagnostics -- whether this comes from lack of knowledge, laziness, or greed, I will leave up to you.

If you actually READ my post rather than just frothing, you would see that I SPECIFICALLY asked whether this was likely to be a DIY fix and did not claim that I would go off fixing things beyond my level of expertise.

Is business so bad for you (or is your reputation so poor) that you need to beat down customers in order to drum up some business? Again, the good service people that I know are happy to help customers help themselves because they know that at the end of the day, the best customer is an informed and satisfied one -- those are the ones that keep coming back, particularly when they need to spend big bucks on a new install...

Name is pretty much consistent with the intelligence and mentality expressed in your post.

Reply to
blueman

Apparently I misunderstood. That doesn't sound like a flame sensor.

I think you'll need somebody familiar with your particular furnace (and its controls) to sort this out.

Good luck.

Reply to
CJT

Obviously, depends on the skill of the homeowner DUH. I save thousands every year by DIY and almost never have to call in a repairman for anything -- certainly, I have never had to call a repair person in to fix my own mistakes.

I think the problem is you can't read straight... I pretty clearly stated that after cycling the power, it burns for a few minutes the first time. Then after the flame extinguishes, it enters a cycle where the flame only burns for 1-2 seconds (or less) before sputtering out.

Please let me know what your business name is so I can be sure NOT to use you on account of: 1. Your screw-the-consumer attitude ` 2. Your inability to read a clear diagnosis of the problem

Actually, even as a "non-pro" ho (as you say), I think it could make sense. Keeping the blower running probably helps disperse and dilute small concentrations of dangerous gasses that could accumulate in a fault condition...

Reply to
blueman

Keep working on it.

Nice and warm here.

Reply to
Oscar_Lives

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