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Looking for help with a intertherm Oil Furnace.
QUESTION:I have a Intertherm oil Furnace Model 461340 with a single blower. The
problem I'm having is that after cleaning the system out last winter it
wouldn't run and after 4 visits by our local HVAC company which installed
the unit not 3 years before showed that not everyone how owns a fleet of
trucks can do a Professional job. Well it's easy to say they will never get
my business again, that's why i'm looking for someone in this group who can
help. Here's the problem the Furnace will run for a period of time but
when the thermostat turns the furnace off it would start back up. The
filters on the furnace have been changed so has the injectors and hitting
reset only makes a spark in the fuel chamber but doesn't start the blower
or create a flame that's remains burning. If you have seen this problem
before I would love to hear how you work it out .
ANSWER: What starts back up? Does the burner motor come on and the ignition
transformer or do you mean that the furnace's blower comes back on. I need a
little more detail to understand what is going on.
Which blower are you talking about? the main furnace blower or the combustion
air blower? I assume that you mean the combustion air blower that is driven by
the burner motor that also runs the oil pump. Normally the ignition transformer and the burner motor are energized at the
same time by the cad cell relay [the primary control that has the red reset
button on it.]. I assume by this that you mean the burner does not come on. Most of the cad
cell relays have three leads coming out of the back and the one ignition
transformer lead and one burner motor lead is wire nutted to the orange lead.
A minority of the cad cell relays have four leads coming out of the back and
with the 3 standard colors [black, white and orange] plus the 4th which is
usually blue. It has been so long since I've worked on a 4 wire cad cell
system that I can't remember for sure but I think that one burner motor lead
goes to the orange and one ignition transformer lead goes to the blue [could be
the other way]. The 2nd burner motor lead and the 2nd ignition transformer
lead are the commons [neutrals] and should be wire nutted with a couple of
other white wires.
If I am reading this correctly [and with your brief explanation of the problem
I might be out in left field], your furnace is going into lockout. Then the
main blower turns off because it is controlled by a temperature switch that
senses heat from the heat exchanger and since the burner is out, then it turns
off shortly.
Since the burner is in lockout, the wall thermostat has no control over the
furnace because the cad cell relay is in lockout.
When you push the reset button on the cad cell relay, both the burner motor and
the ignition transformer should be powered. The burner motor will drive the
oil pump and the combustion air blower. The ighnition transformer will produce
the high voltage that arcs between the ignition electrodes.
If you are getting spark but the burner motor is not coming on then: 1. if it
is a 4 wire cad cell relay, the cad cell relay is probabally bad or the wiring
to the motor is not making good connection. or 2. if it is a 3 wire cad cell
relay, then either there is a motor problem or a wiring problem to the motor.
Does the burner motor have to be reset. The burner motors have a red reset
button on them. If this motor is going off on the manual reset button, then
the motor is going bad or the pump is going bad and dragging so much that it is
overloading the motor.
The above description is NOT a recipe for doing it yourself [in other words, I
don't have any liability for your actions]. It is meant as education on how
your system works. With this knowledge, now you can determine if the
professional service tech you call knows anything about oil furnace
troubleshooting. You seem to imply that the dealer that put it in could not
troubleshoot your problem. To properly set up an oil burner requires having
about $500 worth of test equipment to "tune it up" correctly. CO2 annalyzer,
smoke test instrument, draft gage, etc. Call around and find a heating
contractor that has the proper equipment to tune it up once the problem is
solved. If they have been jacking with it, it probabally really needs tuned up
properly. Most guys that don't have the proper test equipment to set them up
will put to much combustion air to the burner. This will force too much heat
up the stack---- like dollar bills going up the chimney.
LIKE I SAID, OILBURNERS ARE NOT FOR THE NOVICE OR HOMEOWNER TO PLAY WITH. You
can blow one up or pump a bunch of oil into the combustion chamber and then get
it ignited and watch the furnace jump around on the floor.
Hopefully this makes you an informed homeowner that will now know how to
recognize a tech that knows oil. I hesitated giving this much detail because
you really do need a good pro to do the work for you.
Might as well finish the education. The cad cell relay senses flame thru the
cad cell eye that is a photocell. If the burner doesn't light within about 45
seconds [common timing period], then the photocell never gave the proper signal
to the cad cell relay and it goes into lockout.
Do not hit the reset button a bunch of times if the burner motor is running and
the burner isn't igniting. All you accomplish is filling the combustion
chamber with a lot of oil. This is dangerous. Dancing oil furnaces are not a
pretty sight [see above a couple of paragraphs].
Hopefully I interpreted your problem correctly. Have fun finding a "real" oil
furnace tech in your area.
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