CO levels from oil burner

John McArthur_2

I just got a new testo 330-1. i was using a dwyer wet type analyzer.I have a customer with an oil fired boiler.this burner is making about 300ppm of CO with abt 11percent CO2
whats normal? Ive never had a tool that I could read this with.I just know the other burners Ive had the testo on are running CO in the single digits.Am I seeing flame impingment?
thanks mike

Dave Yates (PAH)

missing

What's the O2 reading? Sounds like you're on the fuel-rich side of the CO2 scale.

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jim sokolovic

11% CO2 = 6% Oxygen...

for oil - that's slightly lean or diluted for most applications?

Jim Davis_3

CO Oil

Mike the CO readings at Light-off and Shutdown are necessary to identify the actual problem and your meter may not pick these up. It is impingement of some sort. Your CO2 reading indicate you are close enough to proper fuel/air mixture, but your flue temperature would also be helpful. Could be a bad nozzle or an underfiring problem for starters.

John McArthur_2

oil burner CO

the burner is underfired the boiler is a valiant f100-55 with a carlin e66 burner.the boiler is way too big.so in an effort to reduce short cycling. instead of being fired with a 1.75@ 45degree nozzle I have a 1.00@ 45 in there.The customer insist on a 100 degree water temp adding to my problems(temp runs on reset its about 140 degrees at zero outside] when I pull a smoke test the best i can get is abt a #1 and sometimes I get a yellow spot.the stack temp is abt 450

Jim Davis_3

Underfiring is definitely a cause of high CO on some burners. Just had one recently and by using the same nozzle and increasing pump pressure the problem was eliminated. My second choice if that doesn't drop it below 100ppm would be to see if that Carlin can use a 60 degree nozzle. Hopefully you are using a solid nozzle. The last thing before you change the nozzle would be to adjust the drawer assembly but without being able to check light-off & shutdown this adjustment is more difficult.

Dave Yates (PAH)

CO2 reading

can be identical on either side of the scale: fuel or O2 rich

Fuel-rich side will see much higher CO readings

Here's a link to why:

http://www.bacharach-training.com/combustionzone/advantages1.htm



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John McArthur_2

nozzle

I have an A nozzle in there because the customer said it was too loud that was a misguided effort on my part to quiet the thing down.
Mr davis I need some info on how to get in touch with you about combustion training .
thanks mike

Jim Davis_3

Go to www.nationalcomfortinstitute.com for our information and phone number and call anytime.

jim sokolovic

Quite a while back there was a discussion on this here...

but I would believe that certain characteristics of the flame would clue you in that you are not on the right side (lean fuel) of the air/fuel relationship. I would think that being rich on fuel past the stocio point would produce a tremendously hazy flame with heavy smoke with oil that would be hard to not notice?

Dave Yates (PAH)

sometimes, but not always

I've seen units that supposedly had been tuned and cleaned for seasonal service that were on the fuel-rich side and smoke testing delivered a #6 or higher. Flame "looked" ok.

A recent one I inspected had run great for 14 years until an inexperienced tech adjusted the flame - by eye. Less than a month later,it was clogged shut with soot. No O2 test or smoke test had been performed. The job ticket listed CO2 and a net stack temp that equaled 81% efficiency. The only problem? That unit isn't capable of achieving 81% and the manufacturer's literature specifies the best you can get is 75%. The real net stack temp (which was much higher) when combined with the actual CO2 equaled exactly 75% once the air was adjusted to a trace smoke. O2 was 7.5%, which also was within the range specified in that manufacturer's 1990 literature. BTW, the correct nozzle was in place acording to the annual service sheets.

All of the components (CO2; O2; net stack; draft over fire & in breech; smoke)are necessary for a complete picture. If you're not testing for O2, you're taking one heck of a chance for producing large quantities of CO.

A combustion analysis done prior to the annual clean & tune, followed with one done afterwards works wonders for convincing owners to have that annual check.

My old "dumbbell" combustion analyzer sets served me well, but the newer electronic analyzers we now use are almost too easy and the printout is a great CYA (cover your assets) plus the HO likes to get a copy instead of just a verbal OK.

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jim sokolovic

So does the Oxygen reading...

stay at zero when you are fuel rich beyond this point? Or does it start climbing once past it, as the CO2 starts to drop again. Most combustion analyzers calculate CO2 from the Oxygen reading (if they only have an Oxygen sensor). Isn't the relationship always maintained? If a tech isn't using a smoke gun at least, I don't know what to say about their practices!

Dave Yates (PAH)

news to me

Jim,

That's news to me that the CO2 is derived from an O2 sensor, but I don't make the equipment & can't answer that question. Man, I hope that's not the case. Looking at the charts indicates the O2 should read zero at best if on the fuel-rich side, yet the S-chart indicates CO2 can be mirrored on either side of the chart.

Next time out, I'll have to adjust the air band into the fuel-rich zone and test our equipment to see if we get any O2 readings with a mirrored CO2 percentage. It'll be interesting to see how high the CO percentage goes as smoke gets worse. I'll want a second test instrument measuring CO in the room while fooling with the fuel-rich side.

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jim sokolovic

Well, what type of instrument(s)...

do you use? If the analyzer gives you an Oxygen reading, it has an Oxygen sensor. Does it also have a CO2 sensor that takes a direct reading? Other than chemical or infrared type analyzers, I am not familiar with any that read the CO2 directly. Maybe Jim Davis will rejoin this thread, I remember he had some disagreement with the theory behind the chart we are discussing, and knows the various analyzer methods of measurement well.

Dave Yates (PAH)

analyzers

We have several Bacahrach and one UEI. They give readouts for net stack temp, CO, CO2 & O2. We've replaced (sent out for service and calibration) the O2 sensors several times. The Bacahrach does all on one screen & you can scroll through the UEI screens.

Some day I hope to attend Jim's classes.

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Randy_12

normal CO readings

we get range from a low of 6 to 50+/-. 300 sounds like incomplete combustion. We use Testo analyzers. Old burner?? Wrong nozzle??

Dave Mayer -3 Sons Heating

CO

Hey Mike:
Normally I see levels oc CO ppm between 30-45 on properly running equipment. This is once they have achieved solid state running. I looked up the specs for the boiler burner combo you have. 1.50 x 45b is the norm according to Carlin. If you want to quiet it down etc. I would try a .85x45W Delavan nozzle make sure your pump is @150 psi. Where this boiler is rather long your flame might be "drifting off" as it does not entirely fill the chamber. There is nothing wrong with bringing several nozzles in the basement with you and "playing". This is where I learn the most. Shut off the cell phone so nobody can desturb you and enjoy. Just relax and enjoy your trade. Best of luck, Dave

Glenn Harrison_2

Dave,

According to all the electronic combustion analyzer brochures I have read, CO2 is a calculated number based on the O2 reading and the fuel your are measuring, which you must enter into the meter before measuring. I believe this is due to the extremely high cost of an electronic CO2 sensor.

Ken D.

Checking for CO

An easy way to be sure you are on the propeer side of the curve is to check CO2. Close down air. CO2 should increase. If it decreases, you are on the wrong side. you can also open air and the CO2 should decrease. If it increases, you are on the wrong side. Hope this helps. Ken D. with a capital K.

Dave Yates (PAH)

if so

then I'd expect to see zero CO2 on the fuel-rich side while CO should be greatly increased? Does this render the O2 reading obsolete?

Maybe it's time to get the dumbells out of the archives, replenish the chemicals and go back to pumping!

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Glenn Harrison_2

To the best ofmy knwledge...

the calculation just allows the CO2 to go up as the O2 goes down, but the CO will go up so you know you've gone to far down on the O2. That is at least how my Testo works.

Quite honestly, I don't have anything to do with the manufacturing of these units. Your best bet with any further questions is to contact Rudy Leatherman of Bacharach training @ rudy@eurekanet.com

Jim Davis_3

CO2 & O2 exist on both sides of the combustion chart. Using bottles is like using a polaroid camera to film a movie and provide less accuracy because a flue has to be traverse to find the correct location to do the test in the first place and I don't think this was ever done with bottles.

jim sokolovic

Jim, can you tell us then...

is the relationship of CO2 to Oxygen the same on both sides of the chart? When fuel rich - does the CO2 start going down and the Oxygen starts going back up, or stays at zero, or would you say "it depends"? Why can't we develope a very general chart that shows all this, if the one we now refer to is not complete or misleading? I know we touched on this before, but can you humor the topic a little more?

Firedragon_4

Jim, although

it wasn't done by many, it has been done with bottles and orsats! Learned how to do that in the USAF, but it's a lot easier with electronics, FACT!

Jim Davis_3

O2 & CO2

Not sure if it is the same curve but I don't think it would be something that really needs to be setup because it is a dangerous place to be and to get out of as quick as possible. I have seen O2 readings on the Fuel Rich Side as high as 6%. As fuel input was reduced the O2 fell to 0% and then started back up the excess air side. At one time I had a CO meter that could read over 100,000ppm. By watching the CO drop from over 100,000ppm back to less than 100ppm as fuel was reduced and O2 dropped to 0% & then back up I was really amazed!

jim sokolovic

O.K. , so the Oxygen does not...

stay at zero on the fuel rich side. Seems like that's good to realize for this discussion, and not be misled. "Get out as quick as possible" seems like good advice, too. Notice that I didn't offer to verify this myself!

Jim Davis_3

Just for the record

The 3 or 4 times I have seen this situation has always been on commercial equipment not residential.

Unknown

Jim Solokovic

I have a chart developed years back by Honeywell that goes on both sides of the excess air curve. What is your e-mail address I will send it off to you.

jim sokolovic

Timmie, can you...

post it here, for everyone? I think there are enough others here that are interested in this. If not, my E-Mail is:

jsokolovic@slantfin.com

And to Jim Davis - Thanks for the info., our discussion is very general on relationships of readings - so commercial vs. residential should not be a factor?

jim sokolovic

O.K. Timmie, I received the chart...

Still Oxygen is not shown on the fuel rich side, it stops at zero (at zero % excess air). CO is shown, but there is no question of where that goes here. Dave brought up the subject of what happens with the Oxygen reading as we go fuel rich, but we still have not settled on this fully?

Dave Yates (PAH)

and that's

what I'm wondering about.

With my old "dumb-bell" chemical set, I tested for O2 and CO2 separately. I was told way back when both of the Wilson brothers were alive and running our local Sid Harvey branch that without the O2 test, I wouldn't be performing my work correctly. In reading the Bacharach literature, their advice was confirmed & I spent the extra bucks for the O2 tester.

Now comes electronic testing & a decided improvement in accuracy as well as eliminating the need to play with poisonous chemicals in order to refresh the dumb-bells.

Looking at the chart, it appears CO mirrors, or nearly so, the O2 if you run over onto the fuel rich side and according to their posted literature, it's entirely possible to be on the wrong side without a sooty fire.

So, I'm guessing the chemical CO2 tester would measure to either side, but the electronic units will only give a positive O2 and CO2 reading if on the excess air side of the psych chart?

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Firedragon_4

CO2 is CO2 and I heard

Peter Cullen from Bacharach say that all summer (Carlin U).

Peter said at every session (and I agree) that if the fluid and the instrument are dead nuts then there is no difference in accuracy from an electronic to a 'bottle'. The biggest difference is the need-for-speed, FACT!

The last I heard the DOE was still requiring that final AFUE readings be done (for certification purposes) with an orsat which is a stationary 'bottle', but I've got enough to do and don't stay on top of lab-rat testing.

There is no difference in CO2 and O2 reading in regards to excess air, excess air is excess air. I've plotted CO2/O2 in a lab and in the field before creating the infamous 'Lanthier Scale'.

Although you may be on two sides of zero smoke (trace of smoke/fuel rich, or trace of zero air/rich) excess air will show by percentage of CO2/O2.

The fastest way, IMO, to set a oilburner is with an ohmmeter first, backed up by a smoke tester and verified with an electronic tester. But, after you do enough tests you quickly realize that CO2/O2 testing is just that, verification of the chemistry taking place.

jim sokolovic

In our lab...

we use an orsat to measure the CO2 during an AFUE certification test. Our Bacharach usually gives the exact same reading (to the nearest 0.1 %) as the orsat. If the Bacharach uses an Oxygen sensor to calculate a CO2, and we can see CO2 drop as we go further into a fuel rich mixture - then the Oxygen % must be also rising proportionally in this area. Why all the various charts neglect to show this, and no one seems to be able to 100 % verify this is the mystery here?

Firedragon_4

Regretfully Jim,

I think there's too much assumption out there and so I'll jump in and tell you that many years ago a mechanical engineer who was also a chemist told me there was no difference.

As smoke goes up CO2 goes up and O2 goes down, that's all there is to it, I really think that's all folks!

jim sokolovic

Grrrrrrroooooaaaaan!!!!!

What am I missing here? How can so many people and these charts be in complete disagreement? Dave brings up something that I agree there should be a definitive answer to!

Firedragon_4

Sorry on my part!

Dave Yates (PAH)

Thanks Jim

I completely agree. Seems to me this should be a black or white issue with little fudge room - if any.

If O2 hits zero as shown on the chart and we move over onto the fuel rich side, the CO rise pretty much mirrors O2 percentage wise. O2 should remain at zero until the fire extinguishes itself from a sufficient loss of combustion O2. I'd expect to see a sudden jump in O2 when the flame dies out. CO2 should also remain at zero, which only applies if CO2 is really being calculated on percentage of O2 in the electronic test instruments.

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Dave Yates (PAH)

Unless......

The Oxygen % in the flue gases is being measured with CO too, which would allow for an increase of CO2 being "seen". But that begs the question (in my feeble brain) - wouldn't the percentage of Oxygen in CO be 1/2 that of O2 as excess air? If the instruments are designed to give CO2 percentages based upon O2 readings, wouldn't they be off the mark on the fuel rich side of the scale?

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jim sokolovic

Obviously, our discussion is leading...

toward some "evil dark forest", that no one is supposed to speak of or enter. As I alluded to at the beginning of this thread, there should be certain immediate tell-tale signs that your adjustments are way off. That's why nobody can provide complete analysis of this area. If you ever go there again, and can gather all the readings we are so perplexed about, then please do reactivate this discussion - IF you do return, that is!

Firedragon_4

Jim,

I went over all of my stuff and came up in the same place, so I went searching for a layman's view to simplify it for all of us. No luck and that was even going through the member's archives of the Combustion Institute, go figure!

Then I tried another approcah and found this:
http://www.planet-equipment.com/index.html?gasanalysis.html

jim sokolovic

Grrrrrrrrrrrrroooooooooooooooaaaaaaaaaaaaan!!!!!!!!!!!!!!!!!

O.K. - Went there and read the "Exhaust Gas Analysis" section. Here are some excerpts:

"From this point on (past stociometric), even if we keep enrichening the mixture, O2 will read zero"

"Here's a little secret. O2 and CO should generally be about equal. Tell your friends about this"

"CO2 is inversely proportional to O2. In other words, if one goes up, the other goes down"

Obviously, none of these statements supports the others. The second one is a real doozy - so, at zero% O2, we should expect zero% CO?

This site is for analysers of automobile emmisions anyway, so maybe the same rules don't apply - I still find it contradictive and dangerously misleading!