Weird Beckett AFG burner problem...........(Starch)

captbuderus_2

is on that AFG? Is it the L or v head?If you establish flame and loose it the control will go into recycle. If you establish flame and the cad cell does not see enough light it will lock out, 4000 ohms is alot, and I'll assume you cleaned/tried a new eye. If the higher pump psi fixed it I would run it. Was the co in line (low) with the other readings you got?

John Starcher_4

Yesterday I installed......

...my very first Honeywell AQ251 ODR control. The boiler is a Burnham V83 hot water, powered by a Beckett AFG burner.

The control is a dream to install and set up. My only gripe was lack of instruction in the I/O manual regarding the stat. I was told I needed to use the AQ1000 thermostat for this controller, but could not get it to work. Turns out that for a single zone system, a conventional stat is used. I suggested to H-Well tech support that they add this verbiage to their manual.

Any-hoo, once the wiring was complete, I fired 'er up. The burner ran for 30 seconds and quit - dropped out on flame safety. I double, then triple checked my wiring, and found nothing wrong. I quickly deduced that the problem was NOT the new ODR control, since the boiler was definitely seeing a call for heat, and the circulator was running. The L8174 was showing a flame failure lockout. This burner is using a .6 gallon 60 degree nozzle, running 140 pump pressure for an equivalent firing rate of .75. A low fire baffle is installed per factory instructions.

I reset it, and it did the same thing, so I pulled the nozzle assembly. All dimensions, including "Z" were set properly, air shutters were in the proper position, fuel filter was new, oil tank was full, etc, etc.

I changed the nozzle just for the heck of it, but same problem. At this point I disconnected the cad cell wires from the primary control and read the resistance. I installed a new cell, and it responded to light. Once the burner started, I jumpered the cad cell terminals to allow it to keep running. Resistance on the cad cell was around 4K ohms. It just wasn't "seeing" the flame!!!

Oh, and I had verified the pump pressure was a steady 140 psi, too. At this point, I was pretty frustrated. I called Beckett tech support and relayed to them all the steps I had taken. He said that the flame was not "locking on" to the end cone, and that's why the cad cell wasn't seeing the flame. He suggested increasing the pump pressure to 170. I did, and magically the cad cell now sees the flame. Resistance was around 1300 ohms!!

Just for fun, I backed the pressure back down, and could see the ohm reading increase as I did it. I put it back to 170, reassembled all components, and did a flue gas analysis. I had to readjust my air shutter a wee bit to get my CO2 to 11.5%, and smoke was at zero.

What's weird is that this boiler has been in service for four years, and has run flawlessly since we installed it. I have never seen a case where I had to increase pump pressure to 170 pounds. It's working now, but I would love to have an understanding of why I had to do what I did.

Any suggestions??

Starch

Paul Fredricks_9

Did the draft change? Too much draft can pull the flame off the retention head.

Other than that...ow no.

John Starcher_4

Hi Paul,

I forgot to mention that one of the VERY first things I did was to check the overfire draft. It was rock solid at -.02, exactly per manufacturer's specs.

walnuts

it sounds like you had too much air, is it possible that the air band was adjusted by mistake? seems like a big coincidence that the burner would lock out while a tech was on the job. or possibly were any wiring connections made at the burner where possibly a knock out in the electrical box may have been left open allowing in excess air?

Mark Custis

John

Starch is not just a tech.

He is one of the best oil guys in the state of Ohio.

I am not used to the new Oil stuff, as I hav gone radiant/geo.

Hey John I need a digger in Castallia.

walnuts

no offense intended, but you have to admit if a burner is running properly before you touch a system the first thing to question is what you may have adjusted. if when i'm digging a ditch it caves in i don't blame the shovel

John Starcher_4

None taken, John.

I appreciate the response. Your question is valid, but alas the air shutter position was not the problem. I had verified that the air band and shutter were in the proper positions.

I agree - it ran fine until I touched it, but I honestly have no explanation for what "changed." There are no electrical knockouts, etc that were open, and no other source of air into the burner chamber besides the air band and shutter.

Mark - thanks for the kind words, but I would hardly consider myself one of the "best" oil men in Ohio!!! I'm not even sure I'm the best one in Marblehead :-)

What kind of dig job do you have going on in Castalia??

Robert O'Brien

There are

oil guys in Ohio?

Mark Custis

I am sure you will get it fixed

We are looking at taking a home to geo/radiant, depth of the limestone permitting.

John Starcher_4

I'm not sure...

...how much bedrock you'll find in Castalia. I know that here in Marblehead it's pretty severe.

Try Jeff Kuras at 419-262-7232. If he can't help you, he might be able to recommend someone.

Mark Custis

OK Thanks

Castallia trenching is going to take a look. I will call to get Jeff's thoughts.

BTW pull and inspect the end of the air tube if you have not.

Mark

Erich_3

Nozzle and Electrode Gap

Is the nozzle the correct make and type that is specified? Did you set the 3 electrode gaps using the Beckett tool?

John Starcher_4

Yes, and yes!

All dimensions are correct, the nozzle is the proper size and type. Gaps are set using the beckett tool.

And Mark (from above) the end cone was pristine.

don_185

Odd

That is odd.If no adjustemnt was done to the air or fuel pressure then what could cause a flame to be lean enough that the eye can no longer see the flame.

Is this a two pipe system?Could it be pump cavitation?

Sometime you will find that you may have to go away from a spec nozzle.I would think by raising the oil pressure from 140 to 170 you may now be overfired.

Makes you wonder if it was not running to lean for all those years.

I wonder does the outdoor reset have its own transformer?
If so does it have a dry set of contact for the oil boiler control.

John Starcher_4

This boiler....

...can be fired up to, I believe, 1.05 gph, so I'm not concerned about it now being over-fired. Single pipe oil system, tank is maybe 20' away. Pumping the oil into a bucket from the bleeder showed no air bubbles, and the oil stream was steady and strong. Also, with the pump gauge installed the pressure was steady - no fluctuation at all. I am tempted to go back there and install the .85 nozzle (specs call for either the .60 w/ low fire baffle, or .85 w/ no baffle), and back the pump down to 140 again to see if there is a difference.

The ODR control has a dry contact output to fire the boiler, and it seems to be functioning properly.

Real head scratcher!!

Fred Harwood_3

AFG

I recently had a puzzler on an AFG at 0.85 GPH. Would not stay lit and gave hard starts until I gave up on the Becket setting tool and increased the electrode distance above centerline by a calibrated Goddamnit. OK now. I posted here on this more than a year ago, and some replies noted a changed setting tool? Don't remember now.