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
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
**62 degrees. Why does that feel cold indoors when it feels warm
When you replaced the electrodes you should have replaced the insulators
as well, more than likely they have a pinhole crack in them.
If they are new and you are /positive/ they are not defective then you
somehow installed them wrong.
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
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
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.
As I said, I was looking for a problem that would let it run for 2 or
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.)
Thanks, and thanks Clare.
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
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
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
I wasn't complaining. I'm grateful for your help, and to all who
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
If you read to the bottom of the last post, I said I would, and I
Sounded good, but I remember now that one of the two mornings I woke
up cold, I reset the furnace and it ran, about 40 seconds with no
fire, until it tripped again. The transformer must have been
plenty cold at that time. Yet I think it worked later that day.
Tomorrow I'll measure the resistance of the old one. Then maybe
I'll warm it up on top of the oven while I make a pie, and see if that
IF the observation door is open and I'm standing right there, should I
be able to hear the sound of the electric arc? 1/8 inch in one case,
a little more with the other setup?
But it ran 10 minutes ago, running for 24 hours now since I changed
Quit throwing things at it. Yes, you should hear the "arc".
Regardless: Isolate the problem. If you do not know how to do this,
find someone who can.
If you really want to know how to do this, it *will* put your ass in
Just to fuddy duddy the situation:
My neighbor's truck is having an issue. It's a 1973 Found On Road Dead
truck. Shift it to third and the engine dies. He and his son want to
do "things" by "the well if" thought process, rather than the eliminate
the obvious and go forward with what is really going on. Sort of like
combating old wives tales, and still wanting to get some.
I know that sounds wrong, but...Stop!
Start over and observe. Be patient.
To tell it true: I am reticent to tell you how to find things out.
Just because the system fails at one point does not mean that there
is not something else going on. The stupidest things happen.
My regrets for not paying more attention to this thread. My past two
days have been busy, and today has been rather chaotic.
I'm not, really. I changed the nozzle, then changed the
nozzle/electrode/holder combination. And since the second didn't
help, that means it's something other than the nozzle/electrode.
So I changed the transformer.
(I had a spare xformer from the burner a neighbor threw away.
Originally I just wanted a spare latching relay, a 1" cube with a
clear plastic cover, because mine gave me trouble and I was sure it
was going to fail. Then I thought a whole control board would be good
to have, but now I have a spare everything that's on the burner.
But I didn't even when there was no fire. Another reason to be
suspicioius of the transformer.
That's what I've been doing. That's why I had problems for two days,
but I've had heat for 4 days.
I rarely need anyone to come and do it. Sometimes I need advice.
(But I fix many other things without even posting here.)
You've not obliged to read every thread, not even the threads you have
Sounds like a candidate for an aux. muffin fan. I mount them on most
anything that runs very like stereos, dvr's, large-capacity battery chargers
or anything similar. It seems to have extended the life of a few pieces of
equipment that before fan cooling experienced capacitor failures and other
maladies on an all-too-regular basis.
If you know that your transformer overheats when running too long and that's
happened more than once, it needs some sort of cooling mechanism - perhaps
even the old heat sink from a PC CPU.
On Sun, 22 Dec 2013 00:05:22 -0500, "Robert Green"
Not a bad idea.
Not a bad idea.
I don't have a feel for how much heat the CPU makes, or how much heat
the fan or the heat sink would remove. Maybe if I hold my hand in the
air stream from the CPU (this one has a shroud and all the air comes
out one place) I'll get a feel.
But I've changed the transformer now so until this one starts giving
the same problem, I'll probably not be able to test your idea.
If the insulators are oil fouled they can semi-short and overload the
igmition transformer. Too wide gap can also overload the transformer
and stress the insulators. The insulators can sometimes be cleaned by
removing them, placing them on a clay tile, and heating them with a
propane torch until the oil/carbon all burns off. Only do this if you
have spares in case you damage them trying to clean them.
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