CO levels in flue gas

[retch]

I been doing some startups on some Natural Gas fired Power Flame burner type steam boilers recently and have been have a little trouble getting real low CO readings with my electronic Bachrach kit. I'd like to see zero PPM with CO2 about 9.5 or more and 02 at 4 or less. Sometimes I seem to have trouble getting less than about 25 PPM CO. I guess I can live with anything under 50 as long as CO2 and O2 are acceptable. Of course, with High/Low fire or modulating burners you often have to sacrifice a little on one end to get better readings at the other.

I wonder what numbers some of you guys might be looking for or any other thoughts you might have on the subject?

[hvacpope]

9.5 CO2 with 4 or less O2 is as good as it gets with natural gas,less than 100ppm of CO is good enough for me.
Power flame burners are hard to fine tune, you could play with them for hours and set them really good and a few days later they are out of whack again, they don’t hold the air to fuel settings over time and are sensitive to changes in combustion air temperature and pressure, in my opinion, is better to increase the excess air above 15% just to be on the safe side.

[retch]

Yeah, if I can get 9.5 CO2 and 4.0 O2, I'm pretty happy, but like I say I want to keep the CO as low as possible. 100 ppm seems a tad high to me. Again, those modulating burners can be a real bear to keep happy across their firing ranges.

Power Flame and Gordon Piatt are about the only burners of this type I ever see so I guess I have nothing much to compare them to, but they do seem to be pretty touchy. But 15% excess air? Wow, that's pretty good. If I can get it down to 20 I'm happy and often have to settle for something in the 30 to 40% range.

And what about stack temps? What is the minimum you need to avoid condensation of the flue gases in the stack? About 300 F isn't it?

[hvacpope]

The stack temperature varies depending on the application, for example I seen a Boderus boiler running on high fire with stack temp. of 277 F (after adjusting the fuel air ratios to factory specifications), that’s considered normal in the other hand another boiler made by Burnham same situation but stack temp. all the way in the 500F, no much we can do about lowering it without creating another problem.

[bobby m]

On power flame burners with "damper rod" style linkages you can set them up fairly well as long as you understand that the correct way to adjust mixture is use the damper knuckle where it attaches to its arm (as opposed to sliding the arm up and down on the rod)this way you can fine tune the ratio thru its travel.you can get good readings in high fire than crap in low fire than you readjust the rod and go back to high fire and than those readings are crap,the key is using the linages to adjust the"speed" of the valves im not very good at explaining this but i hope it helps.

[tim fox]

Pope, Bobby,retch, I have a few bryan boilers w/ gordon piatt power burners that I repair/maintain and was wondering what proceedures you fallow to do your set ups. I've been able to keep them within spec so far by adj. linkages and monitoring exhaust conditions with my analyzer according to manual.But have not been formally checked out on setting up these units. I work at a company that doesn't belive in training and spend my own money yearly for seminars.I'm searching for a power burner set up class but for now, I'm still expected to keep these babies running.As I said so far so good but I'll take all tips I can get.

[hvacpope]

Originally posted by tim fox
Pope, Bobby,retch, I have a few bryan boilers w/ gordon piatt power burners that I repair/maintain and was wondering what proceedures you fallow to do your set ups. I've been able to keep them within spec so far by adj. linkages and monitoring exhaust conditions with my analyzer according to manual.But have not been formally checked out on setting up these units. I work at a company that doesn't belive in training and spend my own money yearly for seminars.I'm searching for a power burner set up class but for now, I'm still expected to keep these babies running.As I said so far so good but I'll take all tips I can get.

Tim, the maintenances procedures of those burners are about the same, keep it clean specially the combustion air blower assembly and the scanner, then plug the analyzer close the breeching and adjust the fuel/air ratios till the CO2 levels are 9 or higher and the CO under 100, some of them boilers come with a breeching damper you could play with it and lower the stack temp a bit by closing the damper allowing the combustion byproducts to give more heat, this will throw the rest of the setting out of whack and will drive you nuts going from one end of the boiler to the other adjusting one and messing the other, so I don’t get too anal with the stack temperature, if everything else is sound and the stack temp is a bit higher I'm good to go. One more thing put a few marks on the links and arms helps to put everything back together and don’t get too fuzzy with low fire adjustments sometimes high and low fire will fight each others, you get one right and screw the other, I fine tune the high fire setting and sort of get the low fire on the ball park, that’s one thing that drove me nuts about those burners.

[heatingman]

It's damn near impossible to maintain a 0ppm co level , b/c any time the wind blows or the pressure changes so does combustion in the real world. on paper it's easy to get the results you want. co is too easy to make, any kind of flame to metal impingment, bam co, blower wheel picks up some dirt a week after you clean it bam, co. just keep it under 50 ppm and your good to go.

[boilernazi]

weil mclain boilers require the breeching damper to be set to a positive pressure of.01,,check overfire pressure to see if it matches what the boiler was designed for ,,this will find section blockage usually caused by some idiot not citting the rope wicking and sticking it in between the section tabs,,,,if boiler draft is not set and WIND is effecting the fire the BURNER is NOT SET UP RIGHT,this is a critical setting,,it must be set in the high fire position!!!!!!!!!! good luck,,,,,,,,,,jim

[flange]

less than 40 ppm is appropriate for nat gas power burners.

[JT911hvacr]

Yea I just picked up a multigas analyser today...Called the manufactuer to get there specs on a power flame burner. They told me "3.5-5 o2 on low fire 5-7 on high fire under 50 co ppm also said co2 didnt matter if takeing o2 readings because it was a direct dirvetive of the o2 reading (guess he means you use o2 to calculate co2?)

[slimwoodie]

Yea I just picked up a multigas analyser today...Called the manufactuer to get there specs on a power flame burner. They told me "3.5-5 o2 on low fire 5-7 on high fire under 50 co ppm also said co2 didnt matter if takeing o2 readings because it was a direct dirvetive of the o2 reading (guess he means you use o2 to calculate co2?)

you misunderstood ..

should you be working on Power Burners ..??

[slonergan82]

Flue gases condense at 127f anything above 200 i say