Johnson Air Rotation unit

[HvAckid82]

Hey guys,
Got a good one for you. This one is driving me nuts. Unit locks out, why still on the fence.
Johnson Air Rotation unit M# AR-105EP-10-MG S#K27-8964-5
Power Flame burner M# CR3-G-25 S# 118947109 Invoice # 73147
Honeywell Primary control/Flame control Type R4140L

Natural gas
Combustion results
CO2 9.75%/
CO 0PPM/
stack temp is 441.0 degrees/
82.9 eff/
3.5% O2/
17.9% excess air.
ambient temp is 58 degrees
gas pressure at tap before burner(tee for HGP switch) is 2 " w.c./ This is high fire readings and low fire is the same but gas pressure is 1"w.c.

Pilot gas pressure is 2" w.c.+ 1/2" w.c. air from burner = total pressure 2.5" w.c. Pilot lights right away and reads 6 microamperes and holds steady and low fire starts.

Now the issue, once a day (never the same time) minimum it locks out. Now this is the old honeywell control. I have swapped the flame safe guard with another one on site which was fine, swapped pilot gas regulator and solenoid valve from another unit on site and their maint guy installed a new UV eye.
I have taped all sight glasses into the combustion chamber to make sure no light could interfere with the UV eye.

While I was there, it only happened once, while the unit was in "pre-purge" and just about to go into ignition mode I had a spike in the flame rectifier of like 8 microamperes and dropped (but it WAS NOT in ignition mode, pilot was not activated) and the controller saw this and skipped ignition went thru post purge and went into alarm/lockout.
I hit reset and the damn thing cycled 12 times for me and it was late so we left. WTF? any ideas?
Thoughts?

[HvAckid82]

Anyone want to take a stab at it? I can't seem to find info on the curent honeywell safe guard. I was just thinking about this on my way home but if I remove power to terminal 3 would the controller go into lockout or would it recycle and try the process all over again?

[BKS60]

I saw your post yesterday and frankly I dont think I have ever even seen one of those units so I just stayed quite.

Since you added "if anyone wants to take a stab" it seems like your stack temp is a little on the high side and I have never seen a unit with that low of a manofold pressure.

Any chance the low pressure switch is cutting it out?

[HvAckid82]

The low gas pressure switch is located after the regulator and before the gas valve. Gas pressure before the inlet of the burner is 2" at high fire and there is a high gas pressure switch located just before going into the burner. The low pressure switch is before the first gas valve and is a constant 7"-8" w.c. Now my pressure readings for the burner are after the modulating gas valve which has the linkage for the combustion air. There is a pot for the firing rate of the burner. I made my low fire adjustment with the top shutter and I set my high fire to the correct settings and it will modulate. We set the firing rate at low fire so it runs continuously and if they "feel" they need to increase the rate of fire they can(which they do). I appreciate the response

[Freezeking2000]

Install the new blue honeywell control and a display so you can work on it.

Most likely the contacts between the control and sub-base are shot. You could try to clean them. Most likely the conections are loose and will fall apart. Time for a control upgrade with diagnostic display.

[HvAckid82]

dude you have no idea, these people think this equipment (which is approx 24 yrs old) is in perfect condition. They look at me like I am crazy when I say replace the controller.

[emcontrols]

Have you confirmed the replaced UV scanner is a proper match to the flame safeguard??

[HvAckid82]

yep, correct. dont have the part numbers on me, but that was one of the first thing I checked. wrote everything down and talked to power flame to confirm. They said they are not sure how we could get a stray signal like we are getting esp since this is not an electronic safe guard

[HvAckid82]

yep, correct. dont have the part numbers on me, but that was one of the first thing I checked. wrote everything down and talked to power flame to confirm. They said they are not sure how we could get a stray signal like we are getting esp since this is not an electronic safe guard

[emcontrols]

Im sure you have already checked this but the UV scanner wires are factory all the way to the flame safeguard controller(no field extensions). If so how about any freyed wires at controller terminal block, loose solder connection, etc...

[HvAckid82]

wires look good to the eye. Cant say i saw solder points and uv is only a week or so old and is continuous wire. I have the unit on low fire and it has stayed on the entire time. I raised the temp on this unit and set at low fire so it will not shut down. So now I know there are no issues during the firing stage which is telling me it is in the ignition stage.:limb:
i never use those

[emcontrols]

wires look good to the eye. Cant say i saw solder points and uv is only a week or so old and is continuous wire. I have the unit on low fire and it has stayed on the entire time. I raised the temp on this unit and set at low fire so it will not shut down. So now I know there are no issues during the firing stage which is telling me it is in the ignition stage.:limb:
i never use those

Agreed, how about spark electrode(s). Have you pulled them out to see if tips are burnt off, checked gap (Manufactures spec) and leads for cracking??

[Freezeking2000]

dude you have no idea, these people think this equipment (which is approx 24 yrs old) is in perfect condition. They look at me like I am crazy when I say replace the controller.

The problem is you will have 3K in labor before you replace the 3K control and display. Tell them they need to update the 24 year old POS control, after all you are the boss. Most likely a control issue. I have changed the exact control on the exact Johnson Air rotation unit before. We played with it for 2 years and spent 5K in labor before they broke down and said ok to the new control.

[HvAckid82]

i get it but these controllers have been swapped so it is not thecontroller

[HvAckid82]

i pulled electrodes and it was set incorectly, so many techs set the electrode to spark to the gas nozzle when it is supposed to spark to the metal right in front of the air hole. I get a great reading right away 5 microamperes +- .5

[zw17]

Ok, let's look outside the box...

Have you checked your burner for cracks?

Is the gas line to the unit sized properly? Is the unit getting the volume needed? Any new units on a old existing line that are causing the unit to get starved of fuel?

[HvAckid82]

heat exchanger does not have a crack and the gas line is sized properly. My question is why do I get a quick signal(microamperes) from the amplifier while the unit is cycling from pre purge and just about to go into ignition I will get a quick and sudden spike and the controller sees this and will lockout and go through post purge. Keep in mind when this happened to me the unit was off for a period of hours so there couldnt be a glowing hot spot reflecting light. I call it the "phantom" signal.
The unit didn't even try to light since it saw this signal before trial for ignition. And since I swapped out controllers from another unit the problem still occurs with this one.

[emcontrols]

heat exchanger does not have a crack and the gas line is sized properly. My question is why do I get a quick signal(microamperes) from the amplifier while the unit is cycling from pre purge and just about to go into ignition I will get a quick and sudden spike and the controller sees this and will lockout and go through post purge. Keep in mind when this happened to me the unit was off for a period of hours so there couldnt be a glowing hot spot reflecting light. I call it the "phantom" signal.
The unit didn't even try to light since it saw this signal before trial for ignition. And since I swapped out controllers from another unit the problem still occurs with this one.

Ohm (good ohm meter) the UV scanner, to make sure there is none of the leads to ground.

[HvAckid82]

I have talked to the building manager and they are tossing around the idea of finally going through each unit and upgrading the controller, starter, ing transformer, scanner, electrode, pilot solenoid/gas regulator. So this is positive. They want the controller that can plug into the old sub base without having to rewire everything, this also gives them the ability to use the rm7800 to help diagnose other units with issues

[normally_closed]

outside the box again.....I had an older clever brooks boiler giving me all sorts of trouble. Had the new honeywell control with display module. control would alway's lock out after pre purge during trial for ignition. But would sometimes light and go into high fire after being reset numerous times. I spent a few hours checking everything we all know to check. Turns out the boiler was recently cleaned and the tech that cleaned it didn't tighten all the bolts on the door, both front and rear, air was being pulled in during prepurge = no pilot. Probably not the issue in your situation, just saying it's not always the most technically complicated reason we all try to look for in a malfunctioning piece of equipment.

[spyder00087]

Is there a good ground to the unit?

[HvAckid82]

I didnt trace all the wire, everything seems ok in the unit.

[Freezeking2000]

i get it but these controllers have been swapped so it is not thecontroller

I did not know you had done that. Electrodes are very critical.

[OhioTech]

You said while in " pre purge " it then locked out. I had a Gordon Piatt that drove me nuts. Intermittent failures. I found the auxillary switch in the Honeywell gas valve sticking. I was actually standing beside the unit and seen it through the window, in the valve actuator, I do not know if your burner has this. I have also had the same issue with other safeties connected in the circuit. I was taught at the Gordon Piatt Factory to set Low fire with you butterfly valve and high fire with the regulator. Setting the air shutters effects both high and low fire. The readings that you stated ,looks as though it needs a bit more excess air. Was the readings in High or Low fire. Do you have a digital display that shows a fault code?

[tom number one]

you might try checking to see if you are getting a relection back from the ignition spark.On some of these powerflame burners this can happen and give you a quick false reading. I have had this intermitant problem in the past . Most all of your combustion readings are not out of line. To correct this I have sprayed a flat black paint on the inside of the blast tube to eliminate the problem. This might not be the problem but it's a possibilty.