My oil furnace, forced air, no boiler, just got a new nozzle and its electrodes adjusted etc., and when first turned on, it ran 90 minutes and stopped. In a little while it started up again for 20 minutes and stopped. And a little after that it started up again, but this time it never got going and tripped the circuit in it that's reset by the red button.
Now it's normal for it to shut off for 10 minutes and restart for 10 minutes or more, maybe 2 or 3 times. It sort of surprises me that it does that, but it does..
But this time, it stopped on startup, and even after I pressed the red button, it didn't restart. Didn't know what to do. (It's bad to press the button more than once.) Read stuff online for hours and pressed the red button 8 hours after it stopped. It ran fine at least until I went to sleep 2 hours later.
Woke up cold**. Didn't know what else to do, pressed the red button, it's been running for almost 3 hours, with 10 or 20 minute stops in the middle. But I think it's going to trip some time today.
Any idea what the problem is?
BTW, the red button connects to the top of a relay on the control board.
**62 degrees. Why does that feel cold indoors when it feels warm outside?
Thanks for replying. I didn't replace the electrodes, just bent them a little so they were a little closer to each other, per the spec (1/8")
Yet the burner ran fine for 2 hours. The next day it ran fine, turning on and off as normal, for 6 hours. And it had run fine with the same insulators for the entire previous year.
There's really no choice in how they are installed. They are horizontal, and 1/2 inch above the nozzle port. They point straight at each other and are 1/8" from reaching each other. Their ends are
1/8" forward of the end of the nozzle. They insulators stick out 1
3/4" from the metal circle, instead of 1 1/2, but I can't see how this style of electrode ever didn't stick out 1 3/4, if the electrodes ares to reach the proper place in front of the nozzle. I don't think the
1 1/2 inch dimension is important, just a place to start when first installing the insulators. And in addition, the furnace has run quietly and smoothly for 8 hours with this set of electrodes.
I had hoped one of you would have a cause of the particular symptom I first described. ??? Maybe it's better described in the next paragraph.
Christopher, the tech who did the work was me. I've been cleaning my furnace**, changing the nozzle and adjusting the electrodes for 10 or
15 years now, and doing a good job, after watching pros do it 10 or more times. Most times, after I put it back together, it runs for a year, no problem. What's different about this time is, as I said, it runs for 2 or 6 hours, stopping for 10 minutes or longer several times in the middle, as it has always done, and successfully restarting, Until at one point it runs for a 10 or 20 seconds, never lights, and thus is stopped completely by the timer/flame sensor.
It's only that symptom that I'm interested in right now.
The electrodes are set right or it woudln't run the first 2 or 6 hours. It can't be the filter because again, it wouldn't run the next time. It can't be a leak in the fuel line, for the same reason, and because I dont' smell oil in the laundry/furnace room.
Max, it's a Carrier 85HV085, 85 thousand BTU, 34 years old, starting its 35th winter. My next door n'bor's is the same age and there are other original furnaces in the n'hood. The new gas furnaces are much more efficient, but No, the new oil furnaces are barely more efficient for some reason, except for one special kind whose name I forget that costs thousands of dollars more.
**I had to buy a bigger shop-vac when I started doing my own cleaning, because they do not make soot-quality bags for the minimal size one I had. I guess if I had used it to vacuum the flue (or the fire chamber if that has soot) , it would have sucked up the soot and blown it right through the bag and right into the room with the exhaust ai. The foam filter is even more porous. The bigger shop vac was not that much money, it was cheapest at PepBoys iirc, and the bags take several years to fill, since only one furnace is involved and it doesn't run dirty.
*** and more importantly, it can't be the filter because there is no filter. There's supposed to be one but I've looked and there isnt', not near the furnace, not between the furnace and the tank, and not under the tank. Yet no nozzle has ever clogged in less than a year, and a couple times I've gone two years. The oil must be cleaner than when oil furnaces were first designed, just like gasoline was made cleaner after fuel injection was becoming common. .
As I said, the problem is in the ceramic insulators, there is a small hole in one or both .(Very small and possibly not easy to see) They only cost a few bucks...replace them both and get a few spares.
6 hours, but then fail, and I'm wondering if perhaps the ignition TRANSFORMER could fail when it gets hot enough?
At any rate, I replaced it yesterday afternoon, with one from my neighbor's old furnace, and its been running, with normal pauses, from
5:30 last night to 8:30 this morning, that's 15 hours. Maybe it will last all winter. So far no more changes to the nozzle or the electrodes have been required, but running 15 hours is not the same as running for 4 months.
OTOH, I thought about replacing the transformer a few years ago when I had some trouble getting the furnace to run after changing the nozzle. But I didn't change it and I wish I could remember what I did that time, since I had no more trouble, other than replacing the nozzle, for a few years.
One or two servicemen left behind old insulators, and maybe electrodes or the long copper part that touches the ignition transformer, but that's out of 10 or more servicemen who were here. As the years went on, the servicemen who came here did a worse and worse job. Specificaly, not using a combustion gauge, just their eyes if that, to adjust the fire, and one just taped up the barometric damper, which I read this week is a stupid thing to do.
I knew by the time they were done that they hadn't done it right but I thought it was too late to complain, because if I did, they'd just resentfullly stick the gauge in the flue, pretend to fiddle with the air, and leave.
I should have said what I wanted when I called the place for a cleaning, so they'd tell the guy not to do a sloppy job, but I ended up just doing it myself.
AFAICT only one oil company on the north or west side of this city has more than an oil terminal., actually has an office where they have parts, and maybe I'm too timid, but I've always felt lucky they sell them to me. Without trying to sign me up for oil or repairs.
I still don't think they have pinholes but they are oil-stained. It doesn't wipe off but would probably scrape off with a knife. I'm sure you'd say not to do that but to buy new, right???
I will get new insulators, before I replace the nozzle again.
(Actually I was going to replace the furnace about 2 years ago, but circumstances have interfered. I will when I can.)
The problem could be caused by a faulty transformer /or/ insulators that have broken down. I gave you what I thought was the most likely cause and certainly a very inexpensive option.
Part of normal maintenance on an oil burned is replacing the insulators...but a transformer replacement is not part of a normal PM.
Anyway, if the furnace runs normally for the next few days I'd say you should be OK...but as a precaution I'd still replace the insulators next time you work on the unit.
I was thinking, assuming the furnace works fine now, about whether to save the old transformer, and it suddenly dawned on me.
How come the transformer failed at the same time I replaced the nozzle? And the answer is almost obvious, even if it took me 2 days to think of it. For the last several years, the furnace has probably never run more than 20 minutes at a time, because I turn it on in the fall when it's cold but not that cold out, and from then on the house is 68 or 70.
It's only because the nozzle failed that the furnace was off for 16 hours or more and the house got down to 62 degrees that it took so long to warm back up, 80 minutes, plus soon after that 20 more minutes, almost 2 hours of running, enough to get the transformer hot.
And again after it failed, it was off for -- I forget -- 16 or even 20 hours, and the next day I started it up and it ran for maybe 3 hours with breaks or maybe 6 hours, and by that time it was hot and it failed again.
The "new" transformer is better than the old, but I could put the old back in now and it would work too, because the house is 68 degrees and the furnace only has to run for a few minutes to keep it that way, not enough time for it to get hot enough to fail.
So what I should have done is clean the furnace in the fall so it woudn't have to go without running on a 32 degree day like Tuesday was.
And if this transformer fully fails in the winter, and the house is cold, I can go back to the first xformoer by letting it warm the house
4 degrees, then letting the xformer cool for 4 or 5 hours, then warming the house another 4 degrees. etc.
It's almost as important to me to solve these questions as it is to have heat, and I think this one is solved.
Twice I've taken 2 month** working vacations, November and December, drained the pipes and turned the thermostat down to 50 or 45. It had no trouble warming the house up when I got back because the transformer was fine then.
**I take few vacations, not even one a year, but when I do they are usually long.
I wasn't complaining. I'm grateful for your help, and to all who replied.
Of course not. But I think it accounts for the problem If I had set the thermostat for 64, and then 12 hours after that, 68, it might have worked. If it didn't, I could start over by setting it to 63, then in 16 hours to 66, then in 16 hours to 68.
I'd actually enjoy the chance to try that some time. (but I know myself and I won't unless I'm forced to.)
The transformer is in a sealed metal box, so I can't look at it. I can measure the resistance of the secondary, about 20K ohms, but measuring the primary is more work and the transformer would be cooling off while I did it. Well, it's only 5 or 10 minutes and I should have done it. If it were open, I would have known the problem right away. Next time I'll do better.
(The transformer is probably easier and less dirty to change than the nozzle. And no chance of spilling fuel oil. Loosen one bolt on the right side, move the piece of metal that holds it shut, lift the xformer on the right side so the chamber underneath is uncovered, disconnect its two wires which are attached, each to two other wires, by wire nuts, slide out the electric eye/flame detector from its slot on the transformer base, Put the transformer back. Take out two more bolts on the left side that hold the hinges, and lift the whole thing out. Reverse to install. )
This also means it was a good choice to salvage the burner my neighbor took out.
If you read to the bottom of the last post, I said I would, and I will. :-)
Not one of the circuit board, which has about 30 parts, maybe including an IC, but I understand the wiring of the rest of it. It's pretty simple.
On the circuit board, there's a mechanical relay, with a clear plastic cover, that trips when it tries to run but there's no flame, or I'm sure, when the fire chamber gets too hot, etc.
You remind me that about 20 years ago, it tripped because I'd run out of fuel, and I couldnt' get it to reset. (The red buttom presses on something that goes through the top cover of the relay.) I think it seemed like it had reset, but nothing ran. I took out the circuit board and tried to clean the contacts, and couldnt' get the file in. Then I looked through all my relays for a replacment, then through all the relays in my catalogs, and couldn't find the right size in a latching relay. The next step was to use a relay that didn't fit and run wires to it from the circuit board. But instead I put it back together and it worked and it's been working fine for 20 years!!!!
That was the first reason I saved the neighbor's burner, to have a replacment relay, but I havent' needed it.
We had a problem with our oil fired water heater this summer. Turned out that there's a photo cell, a light sensor, in the combustion chamber that shuts things down if there's no flame. After replacing that, it worked fine.
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