How does one go about testing a burner transformer?

Robert Fisher

New member
I've seen a piece of equipment that one holds up to the contacts... it seems to me that there would be tests that one could do with a multimeter or some other more common tool, no?



Scott Stone

New member
A screwdriver? Touch one contact, and watch the arc to see if it is firing. Be careful, because it can be dangerous.

Ron Musgraves

Exterior Restoration Specialist
Staff member
Yeah, you might DIE. is that a good enough warning. Don't ground yourself an use an insulated tool. I do not recommend you do it. Yes I do it all the time

Ron Musgraves

Exterior Restoration Specialist
Staff member
Jerry will have a meter to sell you, the point is just working on the transformer your self fatalities have happened. Guys have even shorted there washers out, because the hose is steel they grounded themselves an died.

Just fyi

Ron Musgraves

Exterior Restoration Specialist
Staff member
Trying to find the death threads, Robert you have been around awhile. 2004 it says, you must have read those threads?

Just be careful, do not leave bare wires touching the Metal, make sure you put new insulation over any wiring you work on so a short does not happen.

Sirocco Jerry

Active member
OMg !
if any of your spouses were to read threads like this,
.. they might not allow any of "their money" to facillitate a Man-cave. Eh?

A HV ignitor or transformer is a device which can work, but work "poorly" for a while before it actually dies..
if it doesn't throw a spark across a 1/2 to 5/8" gap easily, toss it.
a prolonged "downtime event" is more expensive than replacement cost.

Consider thhis..
Before you set-out to "safely test one"..
You should hinge the HV open, and remove the HV "electrode assembly" ..aka.. "J-tube assembly" (for the way it's shaped),
And make sure dirty or an out of adjstment electrode wasn't the problem to begin with,
as electrode problems easily over-stress your HV ignitor.
..Just be REAL careful not to break an insulator, but inspect them closely for cracks, and adjust them "my way" for reliability..
Click here, scroll down to the electrode adjustment diagram, and be meticulous.
your Electrode assembly should be cleaned and adjusted every year for reliability.
(now watch.. someone will chime-in here claiming he has gone several years without having a "proper" PM program. Just ignore his example)

AFTER you do that cleaning and adjustment, you prove the HV works or not, like this..
If you are lucky enough to have one of my "BullDogPro Tool Box"..
use the un-insulated alligator clip to bridge a gap across the HV terminals of about 5/8"
(Don't use your roach clip for this test.. it might flame-up and get you high in the middle of troubleshooting..
and forget what you were doing, or worse.. another chapter in 10,ooo ways to die.)

Otherwise, a 2" paperclip works o k too, just make sure that clip doesn't slip ..
Any larger gap will stress the ignitor, and possibly damage it, or finish it off !
Now the easy part..
Get into a position you can see the spark-gap safely, with fingers clear,
..and have your helper start the machine, turn on the heater switch, and open the trigger-gun.. just for a few seconds !
If no helper.. reach into that above described tool box, and grab the magnet..
wave it up and down against the top half of the flow-switch, and observe the HV works, or doesn't.
You should hear the fuel solenoid open and close at the same time, and/or the solenoid that powers the HV clicks on & off.
IF you have a pressure switch instead, it's a little more difficult..
you have to open the pressure switch, gently nudge the micro-switch out, and push the button without shocking yourself.
..or just open the trigger gun youself, and remember..
the control circuit opens the fuel solenoid as well as turning on the HV..
Fuel is dumping into the burner-chamber making a larger pool to burn out, or running onto the floor..
Maybe kids shouldn't try this at home.
..If you are not completely clear on how your system functions.. see or at least call a "qualified tech".
Not an electrician,
not a small-engine guy,
a qualified diesel-fired heater technician.

One last thing..
if there are 2 yellow wires connected in there..
be aware this indicates a time-delay shut-off circuit ..
These are less reliable than the HV..
frequently, the controller quits before the HV.. consult a tech that understands
Upgrading to use a remote relay with this delay-off control.
For more on this, you're going to have to come to my Pressure Washer Troubleshooting and BulletProofing class.


Jerry, are you having your Bulletproofing class at Paul K.'s training and certification event in Milwaukee? I think people would be interested, If I was there I would be interested.


New member
You can connect the ignitor to power and then look in through the blower or lift the lid just a little and look in there.


A test of the transformer like how many volts with a multimeter or other kind of testing equipment might be what the originator might have been asking.

Is there some kind of test equipment to show if the transformer is putting out enough voltage or is it like it is slowly dying then it dies?

Checking the spark jumping the gap is a good test but if we could see what the voltage is and see in voltage that it is dying and time to replace it, that might save some aggravation on a job and it would not take long to change it out if there is some kind of testing equipment that is affordable for most contractors.

Sirocco Jerry

Active member
Troubleshooting an HV ignitor ..Easily.

This is why my troubleshooting class is intermingled with BulletProofing..
If your system doesn't have easy-access test-points, indicator lights,
and properly placed gauges, it is not as "easy" to troubleshoot as it should be.
If the system isn't reasonably bug-free, you could be tripping over more than one symptom
whilst trying to identify a single failure.

The "cheaper is better" attitude.. is not a long-term sustainable relationship.
..and the guy that thinks there's an easier way than what experience has refined, is presumptuous and easily a "mis-leader".

Chris, the tester is certainly one way, to indicate pass-fail on the HV, but I figure..
..why own one if there's an equally fast procedure that facilitates other troubleshooting anyway..
The connector on the fuel solenoid usually proves power to both the HV and the solenoid at the same time.
the spark is best proven at the gap, so keep a alligator clip or big paperclip handy.
And to verify power to that end of the circuitry, there should be an indicator light on the control,
..after the pressure switch, after the relay, or whatever.

If the system was not "prepared" for troubleshooting, you mismanaged your investment,
as the jobsite requires the "Rapid elimination of downtime".

On one of my machines, you can test that HV ignitor and prove it has power, in about 60 seconds
..and without having to start the engine.
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