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Aerco Benchmark 2.0 boiler

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Hamp4208

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Discussion starter · #1 ·
Hey everyone looking for someone with some experience with these boilers my company services a school district with about 15 of these boilers in it. The one that im working on has a serial number of G-04-0587. The boiler goes into flame failure few times a week. I pulled the burner off the top but didnt see anything unusual. I go to do a combustion test and with a 40% firing rate and 35 degree fresh air intake temp my o2 should be about 8.7%, at 16% firing rate should be 12% or less and 100% firing rate 6.2%. I cant get my o2 above 4% at anytime no matter how much I adjust my differential regulator or main regulator and my fresh air damper is wide open. Im thinking it might have something to do with the air/fuel valve. I recalibrated the stepper motor. Could the air fuel valve not be letting air by even though it says the correct number on the stepper motor at 100% fire stepper motor says 100. Thanks for your guys help!
-Rich
 
#3 ·
Their is an upgrade that is needed on some of these boilers. Like said before call your rep and they can take care of you.


The future isn't what it use to be.
 
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Discussion starter · #5 ·
Sorry guys been insanely busy past week I haven't even had a chance to go back to job they have 3 boilers there they don't need all 3 at once hopefully get back there this week but I'm gonna call aerco while I'm there and have them walk me through it... Our company had 90 service calls on wed whew I live in the NE temps below 10 degrees this past week
 
#6 ·
Hamp4208 said:
Sorry guys been insanely busy past week I haven't even had a chance to go back to job they have 3 boilers there they don't need all 3 at once hopefully get back there this week but I'm gonna call aerco while I'm there and have them walk me through it... Our company had 90 service calls on wed whew I live in the NE temps below 10 degrees this past week
Click to expand...
Have you find the culprit?
I have similar case where flame failure a few times a week.
 
#7 ·
I am master certified for aerco for whatever that is worth. Your O2 numbers can't be right. O2 over 10% will blow the flame out...that boiler is older then anything I have worked on but...

Does it have a external vfd for the motor or is it constant speed?

Tomorrow at work I will check that serial # and have some better advice...the boilers with the external vfd you have to set the voltage to the motor at different fire rates. I assume the is an older version of the c-more panel.:eek:
 
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#8 ·
I looked at the earliest manual I could find and it was a 2008 boiler that had the external vfd for the motor. On that machine the O2 range is like 5% at 100% fire rate and it goes to like 6.8% at 16% fire rate.

In the factory menu there is a point called ign position it is usually 29%...when I do startups I manual the boiler to 30% in manual then set the O2 to like 7% and see how it lights then I adjust down to 16% fire rate and start watching flame current. I then try to adjust the O2 at 16% to around 7 and 8% and see what gives me the strongest flame signal. Then go to 80% or 100 if your system will allow it and work down the calibration points to 16%. Then Your all set. All of this assumes your ssov gas pressure is adjusted and verified at 30 and 100% :eek:
 
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#9 ·
Have you ever experienced what I can only describe as a burp of the benchmark 2.0? The scenario is that sometimes in normal operation the boilers will have a big rattle or noise from the exhaust stack, and then it goes away. Almost like it's barking like a dog. It can happen once in a while and operation continues fine or sometimes it causes a flame failure.

I should point out that we are dealing with 07 vintage units that have likely not had their O2 calibration done in quite a while. I am currently having my guys look to be sure we are draining condensate well.
 
#10 ·
Mike Cherlow said:
Have you ever experienced what I can only describe as a burp of the benchmark 2.0? The scenario is that sometimes in normal operation the boilers will have a big rattle or noise from the exhaust stack, and then it goes away. Almost like it's barking like a dog. It can happen once in a while and operation continues fine or sometimes it causes a flame failure.

I should point out that we are dealing with 07 vintage units that have likely not had their O2 calibration done in quite a while. I am currently having my guys look to be sure we are draining condensate well.
Click to expand...
I would check you condensate first. They need to be cleaned regularly.


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#12 ·
It's all about combustion calibration, gas pressure and incoming air quality/filter...They modulate from the ignition position to 100%. Usually the lower fire rates, below 50% are touchy. :eek:
 
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#13 ·
Aerco used steel f and t traps for the condensate back then. Aerco has a upgrade or retrofit kit for it.
Also the air fuel valve butterfly would sometimes drop due to setscrew getting loose then stick on bottom of air fuel body.
turn power off and drive valve by hand it should move freely.
when tuning combustion always drive above then down to set point 40% adjust gas reg at 100% iris air damper.
also check flex hoses on inlet air if crushed or inlet not extended it will restrict air.
blower rotation?
good luck...
 
#14 ·
We have the new aluminium traps, but yeah I remember that being an issue. I think we are working to repipe the actual drains from the traps because the pitch may be insufficient. We have established that the air/fuel valve is fine, I stroked it a couple times, and then recalibrated the stepper motor. We can't get the thing to stay lit long enough to change the O2 calibrations.

I am really wondering if there is a way to get the CMORE controller to accept a lesser feedback from the flame sensor, and thus let the boiler run. If it did, then I can run it, redo the O2 settings, and then turn the sensitivity back up. Anybody know anything like that?
 
#16 ·
Factory menu has an ignition % point. Set it to manual at that point. Set combustion at the ignition point then adjust from there...If you can't get it to stay lit I bet the ssov is bad. Try swapping it from a boiler that works...:eek:
 
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#17 ·
we can't get it to stay lit past the point where it proves flame. You think the SSOV is shutting? Wouldn't that be a kind of abrupt shutdown? This shows the flame sense percentage dropping bit by bit and then out.

I can't adjust the combustion calibration if I can't run the boiler, it won't stay lit even in manual mode, and I can visually prove there is flame so I am confused. We are checking the grounds right now.
 
#18 ·
I have seen it before where everything is fine for a second or two and the boiler just goes out...If the flame rod is good and the grounds are solid and there is no voltage from neutral to ground I would look at the ssov. There should be constant 120v , but there is still a possibility the valve is screwed up...I had one last year do the same thing.

It's 4 Allen bolts and 5 wires to swap it and rule it out if all else fails.

One other thing I would try is change the ignition point from 29% to 35% in the factory menu and see what happens. The calibration points are probably 30% and 40%. You have to adjust both to get more or less air at 35% but it should light stronger...If that doesn't get it lit and the ignition system works correctly it points more to the ssov..

One other thing is what is the flame signal when it does run??? 100% on the front panel just means you have > 2ua but the machine should run 9 - 11ua normally...:eek:
 
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Mike Cherlow
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