"Burner Off Delay" goes on forever!

billh

Have a Honeywell R7284U-1004 primary on a Beckett AFG oil burner, with the burner off delay set at 2.0 minutes. Once a week it gets stuck in the "burner off delay" forever, with that message flashing on the display, and the fan continuously blowing air through the burner non-stop (no fuel, no ignition). After waiting a long time (5 to 20 minutes), and nothing changes, shutting the electric power switch off, returns the display to 'Standby," and the burner works for another week normally. No soft or hard lock-out messages on display, or error messages in history. Had the same problem with an 18 year old Honeywell R7184P primary on the same burner (only no display, just flashing LED). Same fix corrected it for another week. Could I be unlucky enough to get two primaries in a row with sticking relays, or am I missing something important?
Note: replaced tank filter, pump strainer, nozzle, all twice (all clean second time), checked wiring (got internal circuit diagrams from Honeywell) and all voltages, both inputted and outputted, for the primary and Honeywell L81148A Aquastat/limiter. They are all correct. In particular, valve on delay turn-on voltage is correct. Igniter throwing good 3/4 inch spark. Pump delivers good quantity of clean fuel out bleeder port during testing. Burner burning real clean and smoke free. All 3 thermostats and circulators working fine. Everything works perfectly for a week till it gets stuck in perpetual "burner off delay."

STEVEusaPA

I'd do some electrical investigation. Specifically a nicked wire, and check neutrals and grounds.
Two things screw up electronics on oil burners (and other things), poor ground, and heat. How hot are the components getting during the run cycle? The correct answer should be 'not at all'.

-2 minutes post purge on the burner motor is usually way too much.
-2 minutes post purge on a power venter is usually not enough.

billh

Did not mention, as space limited, but:
#1. no heat on primary, at temperature of cold cellar. Aquastat on boiler, so gets slightly warm.
#2. Voltage and visual check shows everything grounded, all neutrals also at same voltage, and tied together.

SuperTech

How is the system vented? Do you have a chimney or is it a sidewall power vent? Typically you don't want that long of a post purge if you have a chimney. If you have a power vent the post purge should be longer than two minutes. Usually the power vent assembly will include a post purge control that operates independently of the primary and will energize the burner motor and power vent motor at the end of every burner cycle.
How long was the post purge with the original primary control?

billh

It is vented through a 2-story brick chimney. Both the original R7184P control and new R7284U control are set for 2.00 minute post purge.

SuperTech

I doubt that the chimney or the boiler needs a two minute post purge. Air will draft naturally from the the air band and shutter on the burner as well as the barometric damper.
The R7284U doesn't come pre-set for 2.00 minute post purge! I install several every year and I have one at home. They come with the post purge off, you have to enable it through the configuration menu.

Steamhead

@billh , where are you located?

gerrytheoilman

Love this control have never seen this issue, agree with the others 2 minutes on a chimney is to long unless its a triple pass boiler sometimes the idea to cool the end cone during post purge. Is the boiler grounded? Not saying the control is hung up but if its stuck in post purge past 2 minutes then the control is no good. you could check orange burner wire for the 120v to confirm? Pull off control and see if there is more then one wire on orange lead from Honeywell control. Pictures help alot

BDR529

Follow the wires to the aquastat make sure the B1 and the L1 go to the correct terminals. WM gold oil had some of them reversed.

rick in Alaska

BDR529 said:

Follow the wires to the aquastat make sure the B1 and the L1 go to the correct terminals. WM gold oil had some of them reversed.

I learned that the hard way when I put a gas conversion burner on and wired it to the color code off the factory molex plug. Got the burner running and was fine tuning the mix when the boiler started dancing around on me like it needed to go to the bathroom! Steam was starting to come out of the air vents. I looked at the aquastat and it was at 240 degrees. I turned it off and ran out of the basement as fast as i could. I was able to cool it off by slowly running domestic water, since it had a coil, and went back after it did. That is when I determined the molex plug was miswired from one side to the next. Re-wired and all was good.
That was scary.
Rick

Steamhead

For some reason, pretty much everyone except Carlin uses the black wire to the primary as the "always hot" one, and the red as the "limit" which can actually shut off the burner if a limit control opens. Carlin reverses them. So, we always have to check.

BDR529

Molex!! yup, Can never remember the name of that doobly-doo.