Problem with Carlin 60200-02 Primary Control

ericwill

I have a Carlin EZ-1 burner with a Carlin 60200-02 (Rev C) Primary Control. The control goes into a mode where the pre-purge is very long (20-30 seconds rather than the normal 8-10 seconds) and the post-purge is also much longer (> 30 seconds) and the blower cycles on and off rapidly during the post-purge. The duration between off cycles seems to be random - 1 to 10 seconds. The controller will remain in this mode until I cycle power on the unit.
I spoke to Carlin on two occasions and both times they said the issue was EMI. If so, I can't find the source. I have cleaned the contacts of the igniter and the back ends of the electrodes. There is no evidence of arcing there. I have twisted to CAD cell leads to make them more like twisted-pair. I even went so far as to put a small ( .05 uF) cap across the CAD leads to no avail. I have thus far avoided diving too far into the burner so I haven't checked the electrode gap. I don't want to make a marginal situation worse.
Any ideas? The cycling can't be good for the controller and probably isn't doing the burner motor any favors either. I am on the verge of swapping in a Honeywell controller.
Any advice would be greatly appreciated.
Thanks,
Eric

SWEI

Grounding issue?

ericwill

Carlin mentioned grounding. Are we talking grounding for the controller or for the entire burner/boiler? How should the controller be grounded? I suppose it's possible a ground strap/wire has come loose or corroded.
Thanks,
Eric

SWEI

Testing the effectiveness of an earth ground requires specialized equipment, but you can start with the low hanging fruit:

Are the boiler and burner on the same circuit? Is anything else on that circuit? Measure the AC voltage between the white wire and the green wire at the last junction box serving the boiler and burner.

ericwill

Thanks again for the guidance. I'll check it out.
The boiler and burner are on the same circuit. I don't think there is anything else on the circuit but I'll check.
I'll also check the resistance between the ground coming into the junction box and earth ground. The distance between them is short enough that I should be able to rig a low-resistance "extension" to my ohmmeter probe.
Eric

SWEI

First check to see if there's any voltage between white and green. Check the resistance if the voltage is zero.

BTW, how will you know what "earth ground" is?

ericwill

I always check both AC and DC voltage before switching the meter to resistance. I've learned that the hard way.

I'm taking as earth ground the point where the copper spike goes into the ground next to the house. Maybe that's an incorrect assumption. Should I be using a different reference point?

What I haven't seen in any of the wiring diagrams is where the 60200 control picks up ground. The control is mounted to a plastic plate which, in turn, mounts to the j-box on the burner, so no connection via the case. The neutral is brought out and connected in the box. I didn't notice a ground wire. Any ideas?

northernboiler

I have seen this problem with the post purge cycle before. Plus other "similar" issues with this control.
The only reason I have ever been able to explain it is that control has a problem on the circuit board.

Sometimes "problems" like these just cannot be explained. Because there is nothing outside of the primary control that wrong or causing the issues.

Simple answer, replace the control.
I install the carlin pro-Maxx 70200 controls exclusively now. And have never had one problem with any of them for two years.

ericwill

Hi northernboiler,
I'm inclined to agree with you. I wanted to do a reasonable amount of troubleshooting before pulling the trigger on replacement. I also was not eager to substitute a new set of unknowns for my current known problem.
I'm curious though. Despite the problems you observed with the 60200 you stayed with Carlin. Any reason? You could have gone with a Honeywell 7284u.
Eric

northernboiler

I like the 7284 control. The reason I prefer the carlin 70200 is because it offers more features and diagnostic capabilities.
For example the LCD screen displays more information than the 7284. It provides more power terminals for added options (nozzle line heater, blocked vent switch) and has alarm contacts (which are used more in commercial applications, but I am beginning to see more in residential applications).

I also have a good relationship with Carlin/Hydrolevel.
I find their tech support and local representative to be knowledgeable, helpful and supportive.

Also as part to have in stock, it is considerably easier to have one universal part that can handle the majority of residential and commercial applications and for various reasons.

One last thing, I have seen, on more than a few occasions that the LCD screen on the 7284 has stopped working. The control works fine, but not screen info, it is blank.

This is only my opinion, in the end, either control will solve your issue, and operate correctly.

ericwill

Wow. All good reasons. I, too, have had good experiences with Carlin tech support. As an electronics engineer with 40 years of experience with microprocessor based design, I'm a little skeptical about the EMI diagnosis, but I'm willing to be proven wrong.

BobC

I've had difficulty with low level circuitry when it is sensing high voltage areas that are subject to arcing. There are many things that can go wrong if you don't guard the inputs just so. An arc can cause ground bounce that can drive the input of the sensing circuit negative and when that happens all bets are off.

That causes the system to do all sorts of weird things and the military does not like weird things happening in their fighters cockpits.

Bob

ericwill

Very true, Bob. Perhaps "EMI" is not quite the right term. You describe a combination of input susceptibility and power line susceptibility. If I had to guess, I'd put my money on input power. As you say, big inductive loads are being switched nearby. That will definitely put spikes on the power lines. If the power supply on the control brick droops during these events or ground bounces, then that could cause all manner of weirdness. As to inputs, there aren't many - the CAD cell and "limits" 120VAC input in my case. Both can easily be isolated from or conditioned for the low level electronics, but are they?
Perhaps if or when I replace the control, I'll tear open the old one and be able to stop speculating.
Eric

ericwill

Ok. Here's a status report.
I pulled the combustion head assembly out to inspect it. The igniter electrode points were spaced about 3/16". Spec is 1/8" to 5/32". I put them back closer to 1/8". The retention ring was a bit sooted up. More than I would have expected. I cleaned the soot off with a rag. I will ask about it when I get the boiler professionally serviced/tuned.
After re-assembly and watching a few cycles I am happy to report that the pre/post purge timing has stayed rock solid for the last 3 days. The boiler sounds smoother, less rumbly, in operation. I suspect the soot was affecting the turbulence of the air in-flow.
Thanks to all for the great suggestions and advice.
Eric

ericwill

Hi All,
Here's a status update one year on.
Still pursuing the EMI theory, I narrowed the ignitor points gap to spec last year. It was slightly too large, but not outrageously so. I convinced myself that my problem with post-purge cycling was significantly reduced if not cured.
Fast forward to this heating season.
I had no problem with p-p cycling until about three weeks ago. This coincided with a cold snap that saw the duty cycle of the boiler increase significantly. As before, cycling power on the boiler clears the problem. Shutting off power to the boiler for a few minutes seemed to keep the cycling at bay for longer. My new theory is that the 60200 Controller has a bad solder joint on the circuit board or a bad wire bond inside a chip that becomes intermittent as the board heats up.
I am replacing the 60200 with a 70200. I can't have the Controller putting the motor at risk, or worse, running in some unknown state that could call for oil without the ignitor running. I will take another last look at ground potentials as SWEI suggested last year. Maybe I missed something. Chances are, though, that my next report will be on my experience with the new Controller.
Thanks again for the sage counsel.
Eric