7284 U Oil Primary

RayH

I replaced the primary on a warm air furnace. It runs now and the blower comes on OK.On the next call for heat the control shows trial for ignition and locks out. I replaced the cad cell and the control again and adjusted the air. It has been cleaned 2 months ago. Any ideas guys?

mgdesrochers

Igniter? Electrodes clean with no cracks in the porcelain and properly adjusted? Oil pump pressure? Solenoid valve operating properly? Oil line clear and leak free? Could be any of those or could be something else but I would start with these things first...

Ironman

You may be running too lean. Have you done a combustion analysis?

Robert O'Brien

http://s3.supplyhouse.com/product_files/R7284-INSTALL.pdf

You should be able to use the stored data to troubleshoot

EBEBRATT-Ed

plugged nozzle, filter

newagedawn

how old is the ignitor? does it have a solenoid? those go bad also, i agree with eberatt, ive seen bad nozzles also,

RayH

It has an electronic igniter. So far I changed the primary, complete cad cell, motor, nozzle. Also adjusted the air. I have a company Rep coming out this afternoon.

Ironman

Does it have a Becket CleanCut oil pump? If so, the solenoid may be bad.

Otherwise, look at your air/fuel mixture being too lean which would cause the flame to give of less light output and that in turn would cause the flame signal from the cad cell to be too weak.

That's why I asked about a combustion analysis. You won't get it right by fiddling with the adjustments. You've gotta use instruments. It's not your grandpa's oil burner. The new controls are very finicky.

RayH

Bob, So far I have changed the Primary twice, motor & coupling, complete cad cell wiring, nozzle. Air has been adjusted. the unit starts and runs fine. When it attempts to start the 2nd time, the primary counts down trial for ignition. The motor never starts and the primary goes immediately to a hard lock out. pressing the reset it starts right up and runs full cycle.

Ironman

Have you tried bypassing the limit switch?

RayH

Where is the limit switch on a warm air furnace?

Harvey Ramer

So the next question would be is the motor getting power on the second try. If it is, It's not the primary. Next step, check for continuity between the motor leads. If they are open, the motor is off on THERMAL. This can be caused by either bad bearings in the motor or the fuel pump. Likely the fuel pump if the motor was replaced.

Another thing, does it have a power Venter? If it does, the installer may have wired the power to the motor to be interuppted in the event that the power Venter doesn't make the VACUMM switch.

It's also possible that you may be hitting a high limit switch that disconnects power to the motor. That is unlikely, however.

RayH

Harvey, Thanks for your reply. This is a warm air furnace in a trailer with no power vent. The fuel pump holds 100 psi.

Harvey Ramer

So the thermostat is likely wired directly to the T1 T2 terminals on the primary? If so, the limit switch will likely disconnect power to the motor.

Time to get busy with your multimeter. You have to do further diagnostics before your problem can be identified.

Steamhead

Call a pro.

RayH

I'm waiting on a factory rep

rick in Alaska

If the motor is not getting power on the second call, it sounds to me like a bad primary. Even new ones can be bad.
Rick

HVACNUT

Is this a Miller down flow furnace?
You mentioned that on the 2nd cycle the primary counts down to ignition. That tells me there is a delayed oil valve on the pump and a prepurge. You say the motor doesn't run during this countdown phase. The motor should DEFINITELY run during prepurge.
What brand and model primary.
Can you post a pic of the burner?
I think the primary might be set up for prepurge, but you don't have a DOV.

RayH

I do have a DOV w/ a Beckett burner

HVACNUT

Ok, you have a DOV. I guess the Beckett Clean Cut Pump. And you're using the Honeywell 7284U? In the installer setup, it's programmed for prepurge? How many seconds? Programmed for interrupted ignition?
The motor should definitely run during prepurge.
L1 and limit spliced to incoming power.
Orange - motor
Blue- igniter
Violet - DOV

Aaron_in_Maine

Doesn't sound like your getting power to the motor. I would check for power on the orange wire during the countdown. It could also be your programming is not right.