Combustion testing of the oil furnace part 2

[@danielarnold6862]

I would try a different nozzle (smaller) to get the stack temp down. Also check the fan of the nozzle. May need a wider or narrower cone shape. Then your smoke and analyzer readings should come in better.

[@geojor]

efficiency is very important, healthwise and moneywise, thank you for this great information...

[@mgarozzo11]

I re-watch this video every couple years before doing my maintenance to refresh my memory. One thing I dont remember you mentioning is.... what is the ideal location to put the combustion analysis probe? I've tried a couple different spots and seem to get slightly different readings, I'm assuming somewhere between the draft vent and 90 degree bend I have coming from the furnace but always wondered if there's a way to figure out which is giving the most accurate readings.

[@grayfurnaceman]

As close as practical to the furnace, and before the barometric. That's the best I can come up with. GFM

[@mattfoley6082]

Can't thank you enough for your videos. By far the most informative I've found. I'm a homeowner with year 1990 Peerless boiler with tankless coil and AFG 2 burner. If you can answer some questions I'd really appreciate it. 1. What should I be paying for a complete tune-up? I live in Phila.suburb. I used to have an old guy come out and he charged less than $100. Since then I've had a few guys who charge $200 or more. 2. No serviceman I've used has ever done a combustion analysis or efficiency test or draft check. Is this normal or have I just been unlucky? How do I find a technician who knows what he's doing? What questions should I ask? (Many homeowners are quitting oil heat and switching to gas and I suspect it's harder to find someone who knows how to service oil correctly.) 3. Please explain function of air band and air shutter settings and how to find optimum setting for each. I can't find any info about these and I've been looking for years. I contacted Peerless but they don't have a manual for my unit. 4. What's your opinion on nozzle types (solid, hollow, etc.) effect on efficiency/clean burn? I plan to keep my current system as long as possible. Not interested in spending thousands on a new system just to improve efficiency by a few percent; would take many years to break even. Thanks in advance and I look forward to your reply!

[@mattfoley6082]

+Matt Foley Correction: my burner is AFG, not AFG 2.

[@grayfurnaceman]

+Matt Foley The $200 service is pretty normal. All oil furnaces should have a combustion analysis and smoke test during the service. This is for both efficiency and dependable service through the year. Ask if they do combustion analysis before the service. In most cases, the air band should be closed unless the furnace is over 200,000BTU. The air shutter is used for most applications. The setting is dependent on the combustion analysis readings. Nozzles are also dependent on service settings and the oil source. Hope this helps. GFM

[@erth2man]

It seems like the smoke test is the deciding factor. Even if you could get the O2 and Co2 readings to where you wanted, it would still come down to a final adjustment dictated by getting the smoke down to a zero reading. I'm starting to wonder why wouldn't you sneak up with tiny air adjustments taking smoke readings until you finally got just to zero smoke and simply leave it at that?

[@grayfurnaceman]

You could use smoke tests for the final. In fact, that used to be the way all techs did it. The 02 and C02 readings just get you closer. GFM

[@Deep_Divers]

Great Instructional videos! Keep up the good work!

[@grayfurnaceman]

Thanks. I will be doing some more on combustion efficiency as I get time. GFM

[@linandy1]

I like that gadget your using.

[@mainelyelectric]

Another question for you I am just wondering what your thoughts are about what’s the approximate btu output of my miller furnace in my greenhouse you helped me with. The nameplate says 85,000 but that is if you had the maximum nozzle size installed of .71gph but I have the .50- 579 nozzle installed at a pump pressure of approximately 135psi and it’s running great! I was thinking maybe 70,000btus??

[@exflow2000]

Hi, thanks for your super videos they help a lot of people. I see you use the fieldpiece for you readings. I know that instrument does not read co, what do you use for that reading. A Bacharach? Is so can you do a video on how it works and how to use it.

[@grayfurnaceman]

Its an SCM3 fieldpiece, and I will be doing a vid on it. Thanks for the thoughts. GFM

[@kathykoopman4168]

I have a 5 year old Burnham oil fired boiler coupled with a stainless steel liner in the chimney. Every year, I have the boiler serviced and I found over the past few months, that when the boiler stops the damper plate slams to a close. Your feedback on what could be causing the damper plate to close like this would be greatly appreciated. Thank you for your time - John

[@grayfurnaceman]

Has the damper changed in the way it closes? GFM

[@Samos12]

My stack temperature is a over 600 (thermometer stops at 570). My thermo-pride manual says I should have a temp below 500. My air intake has got me right at 0 on the smoke checker, and my draft is -4. My nozzle is .50-70A. Anything I can do to get my temp lower? is it "okay" as mentioned by Dan below to use a smaller nozzle? Any down sides to using a smaller nozzle? Thanks!

[@grayfurnaceman]

You are pretty close to as low as is practicable. A .4 is about as low as I would go. Smaller nozzles tend to plug easier and if the burner head is not sized for your nozzle, it won't be efficient. GFM

[@Samos12]

@@grayfurnacemanThanks! I ordered a gauge, so next I'll check my pump pressure...

[@simclardy5281]

great video.

[@mainelyelectric]

I was just curious what do you think the normal exhaust temp is for my miller furnace I have been working on?

[@grayfurnaceman]

I would think the lowest would be about 375F net. GFM

[@bigpardner]

Is the stack temp readout in that device net or gross? Also, given the boiler with the same setup; nozzle, pressure, degree of cleanliness; if you get the recommended draft and smoke at barest trace or barely zero, how much further can you tweak it using more technical devices? IOW if you have draft and smoke as good as you can, how much better can you get it?

[@grayfurnaceman]

+bigpardner It calculates net. You can get close with smoke patch and draft. But nothing beats the analyzer for accurate combustion analysis. GFM

[@Karnol428]

So you don’t go off of CO2? My school is texting me about the CO2% reading trying to get it in the parameters of CO2 is this wrong?

[@grayfurnaceman]

The meter reads oxygen and calculates CO2. GFM

[@Karnol428]

@@grayfurnaceman so when doing the analysis you want to watch your oxygen levels mostly but calculate to not have to high of CO2 to try to avoid soot build up?

[@grayfurnaceman]

@@Karnol428 The analysis must be coupled with a smoke reading of 0 for flame retention burners. You sometimes will have to compromise your adjustments to get that 0 smoke. GFM

[@Karnol428]

@@grayfurnaceman That makes sense. Get 0 smoke levels and try to get your analysis in the correct parameters the best you can with 0 smoke

[@electriccar3253]

@@Karnol428 You got it. GFM

[@mgarozzo11]

i have 2 identical beckett afg burners on identical furnaces, I set the o2/c02 the same on both ~5.8% o2, one reads 20 on CO and the other reads 100 on CO. I put new nozzles in both but cant seem to get the one burner under 100CO eventhough the analysis looks good otherwise. I know thats right on the border of being dangerous, could it be something simple like a bad or clogged oil pump? or something more serious like a cracked heat exchanger? Thanks!

[@grayfurnaceman]

First, replace the nozzle. GFM

[@mgarozzo11]

@@grayfurnaceman already did. No change unfortunately

[@grayfurnaceman]

@@mgarozzo11 Check gun depth, probably should be 1,1/8" back from end. Also be sure burner head is clean. GFM

[@mgarozzo11]

@@grayfurnaceman Looks like you were right! I ended up buying a beckett z-gauge for the gun depth and it was only off by a tiny amount but it made a big difference. at 495 stack temp, 6.2% o2 and a 1 on the smoke test I'm now getting 20 on CO and 29 on COa . I think its a little more air than I'd want but if i take out air I get more on the smoke test, CO stays low either way. I think I'm good with it like this, way better! Thanks again for the suggestions.

[@quimshtgclg]

Is that chart for oil burners only ,or could it be used for gas

[@grayfurnaceman]

That one is only for oil. GFM

[@quimshtgclg]

Thank you sir .

[@RonAmundson]

I've got an issue where I need to really add a ton of excess air in order to get the smoke numbers down. I can't get a smoke 1, until I drop the CO2 under 10.7%... which then drops efficiency down to the lower 70's. At a 12.3% CO2, my efficiency is running right at book value at 84%... but my smoke is running around 4-5. I'm assuming this probably means there is a flame issue, or something wrong in the combustion chamber? Its been 3 decades since I worked on oil furnaces, so no doubt I am missing something somewhere. I've got an inkling that my front to back nozzle distance is off, and or the guy who cleaned things missed something? Does this make sense?

[@grayfurnaceman]

I would be looking for impingement or combustion chamber problems. And certainly the gun depth with a flame retention burner. Also a dirty fan. Look for air leaks around the burner and burner head damaged. GFM

[@ghostridergr8259]

one more question is , how mutc deep i must put the burner into the boiller? if we dont have the manual wich is one right choice to not have problems ?

[@grayfurnaceman]

The end of the head should be about 1/2" back from the edge of the combustion chamber. GFM

[@ghostridergr8259]

+grayfurnaceman i am very sorry for my English you mean deeper in the boiler 1/2 or hide in the fireproof material?

[@ghostridergr8259]

OKKKK AFTER THE TEST on 3:44 WHAT HAPPEN WITH THE CO2? MAUBE gos down from 11,5 % so thats mean the maximun clean air with the maximun combasion is that?

[@grayfurnaceman]

I probably should have shown it, but the meter calculates CO2. It does not measure it. GFM

[@ghostridergr8259]

ok ... calculate or measure it for me seems the same , beacause i read we haft to have 12.5 or close to 12,5 , so some times its impossible to take 1 level smoke with 12,5? pls try to explaine me ! for this reason i ask you to put a video with the steps and what we got to do and what we can do!

[@grayfurnaceman]

First, have you watched all the parts of the combustion analysis? If you have and are still unclear, I will consider an additional video that will give an overview of the analysis steps. One thing I may be able to clear up is high efficiency in the oil furnace as tested by combustion analysis may yield poor smoke numbers and in the end, you must have good smoke numbers or the furnace will soot up. GFM

[@danieltoomey4059]

Replace the furnace