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Smoke pump question

SlamDunkSlamDunk Posts: 560Member
I dont usually work on residential furnaces (oil) but circumstances forced me to. It is a new Armstrong 85% forced air with Beckett NX burner.

I bought a smoke pump for the job and did an “as found” test several times and came up with zero on the scale then a combustion analysis which yielded bad numbers. The furnace was grossly sooted up. After cleaning soot out of furnace and flue and tuning burner, i did another several smoke tests and was still a zero on the scale.

Yet, the filter on my test probe was completely blackened during tests/tuning. Concerned, I replaced filter and left probe with analyzer on in flue all day while the furnace did it’s normal thing and the filter was in the 0-1 scale range. closer to zero. Why didnt I pick anything up with the smoke pump during “as found “ tests?

Comments

  • STEVEusaPASTEVEusaPA Posts: 3,083Member
    If you blackend the filter in your trap, but got nothing with your smoke gun, your smoke gun isn’t working. Depending on the type of gun, if it’s a Bacharach, the spring might be hiding the fact that the tube wasn’t fully connected.
    Kinda hard to explain, but with the paper in the gun, tube folded/clipped on holder (like you’re putting it away). Put your thumb over the end of the tube, pull plunger a few inches. That should be all you can easily pull, and it should hold or pull back slightly.
    Taking a test (for those who may not know):
    3 full seconds for a complete pull stroke, hold 1 second, push stroke 3 full seconds. Repeat 10 times.

    Now regarding an NX, I’m curious as to how you tuned it without adjusting the air? IOW, steady state, draft, smoke, then analyzer.
    Also with the NX, you have to confirm 0 on the head adjustment (against the stops) then move head to its recommended starting number.
    I also noticed there is not a whole lot of adjustment from trace of smoke to true zero smoke to yellow on the paper (too much air).
    steve
  • DZoroDZoro Posts: 771Member
    What are your combustion analyzer numbers?
    You can't set up on smoke alone.
    D
  • SlamDunkSlamDunk Posts: 560Member
    As found numbers: stack temp 700*; O2 3.5%; CO 4ppm; CO2 11.2% ; Excess air 27%. Efficiency 78%; draft +0.008inwc. Burner air setting found at 3.

    As left numbers: stack temp 503* ; O2 5.5%; CO 1ppm; CO2 11.8%; Excess air 30%; efficiency 83.3%.; draft -0.02 to -0.05inwc.
    Burner air setting left at 4.25


    The pump was a bacharach.

    I probably should have spent more time on the smoke pump; I did the slow stoke method per instructions. I was overwhelmed by the soot problem and, until I saw my probe filter, I thought flue gases were clean.

    When I pulled the burner, it looked like nozzle assembly was full forward. I didn't drive pointer to zero; probably should have but I also read in beckett documents that if gun was assembled to burner at factory, this was already done. I'll be going back in a couple months. I will double check everything.

    The installing company was called back after a week when soot chunks were found spilling out of draft damper. After they cleaned furnace and "tuned" burner, they (again) did not leave combustion results. A month later, there was evidence of soot in flue near damper.

    We didn't want them back so, I flew up with my stuff and did the best I could. We installed a flue thermometer to at least watch the temp. During normal cycling, temp stays in 400-450* range.

    Thanks for the responses.
  • SuperTechSuperTech Posts: 938Member
    Wow those as found combustion numbers were awful! I haven't had any experience with the NX on Armstrong furnaces, but I've worked on several Carrier/Bryant furnaces with the NX. They leave very little room for error, one mistake and they soot up. Looks like you did a great job with the Armstrong.
  • SlamDunkSlamDunk Posts: 560Member
    SuperTech said:

    Wow those as found combustion numbers were awful! I haven't had any experience with the NX on Armstrong furnaces, but I've worked on several Carrier/Bryant furnaces with the NX. They leave very little room for error, one mistake and they soot up. Looks like you did a great job with the Armstrong.

    Thank you. But I have a nagging feeling I'm not done yet. The "one mistake " thing and two sooting events before I got there is bothering me.
  • SuperTechSuperTech Posts: 938Member
    edited February 26
    I would feel good about it if it were a Carrier with those combustion analysis numbers.

    The most common mistakes I see made are guys not testing anything and figuring that it's good to go out of the box, wrong nozzle after service ("this one is close enough"), and guys doing a smoke pump test and nothing else.

    Do you end up leaving the spline nut off? I always do. I can't adjust the burner with it on and not have the damn nozzle line leak. I don't understand the need for the NX when the AFG is a fine burner.
  • SlamDunkSlamDunk Posts: 560Member
    edited February 26
    Per instructions, I loosened spline nut before adjustments and re-tightened with fingers: snug + a little more. No oil leaks while I was there.

    I don't think the installers did anything. I have read burner ships from factory set at 3. That is where I found it.
  • SuperTechSuperTech Posts: 938Member
    You were able to loosen it with the nozzle line on? I've found that once loose it seems like I can't properly tighten the nozzle line to avoid leakage. I knew I was doing something wrong, but I have had no problems with leaving the spline nut off. Keep me posted on what happens with the Armstrong, hopefully you won't need to go back.
  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,921Member
    @SlamDunk

    Looks like smoke to me on your first set of #s.

    Your second set of #s look pretty good. I would check your smoke tester as @STEVEusaPA mentioned. Some say adjust for 0-trace and then take a Co2. Then open the air to drop the Co2 1 point. leaves a little cushion
  • SlamDunkSlamDunk Posts: 560Member
    edited February 26
    I will check smoke pump next time I'm up. I know I should have seen smoke on test strip. I didn't understand why results were negative.

    I feel ok (not great) about the job after I left analyzer on all day with little trace of smoke on probe filter; It's not the way I wanted to test for smoke but I reasoned the analyzer's pump is on continuously. If there was a problem, it would have blackened after 8 hrs. It didn't.
    I left the smoke pump up there.

    Thanks again for the feedback!



    The dirty filter was after a couple hours. Of course, I did remove a lot of soot and some may have been en-trained in exhaust air. The stuff on clean filter was likely from handling. I looked like the dirty filter after cleaning furnace.

    I know I didn't get all of the soot out with brush and vacuum.
  • SuperTechSuperTech Posts: 938Member
    Especially with furnaces it's pretty hard to get it completely free of soot in a reasonable amount of time.
    Sometimes the seal in the smoke pump dries out and no longer pulls a good vacuum. It's important to lubricate the seal annually.
    What kind of analyzer are you using? I've never seen that type of filter before.
    I think you are good to go. Low CO, O2 and CO2 and draft are all looking good.
  • SlamDunkSlamDunk Posts: 560Member
    Smoke pump was new out of box. I didnt add lube that came with it. Testo 330
  • SuperTechSuperTech Posts: 938Member
    > @SlamDunk said:
    > Smoke pump was new out of box. I didnt add lube that came with it. Testo 330

    I'm not sure what happened then. That Testo 330 sure looks nice. I was drooling over one at my local supplier recently. I have been using the Testo 320 for years now and I love it. Are you happy with the 330? I'm not sure if it is worth the money to upgrade from the 320.
  • SlamDunkSlamDunk Posts: 560Member
    edited February 26
    I'm happy with it except for the cost to calibrate/repair.

    My next analyzier will be an e-instruments BTU 1500 with blue tooth. My boilers' stacks and autoflame controllers are very far apart. It would be nice to tune at HMI with my phone and not run back and forth.

    Less expensive too.
  • STEVEusaPASTEVEusaPA Posts: 3,083Member
    I think you did a fine job also.

    I always zero out the head on this burner, or check the z dimension on other Becketts the first time I touch the burner, or if anyone else touched it since I been there last. On the other Becketts I'll outline the escutcheon with with a sharpie.
    There's no telling what another tech will do/try when there is a problem. Even had an AFG, brand new, sooting up the place and 500+ (can't remember exactly) PPM, that my buddy installed.
    Turned out he couldn't get the nozzle assemble out and completely removed the escutcheon plate. Then inadvertently flipped it when he put it back on.

    The Bacharach Insight Plus is a good choice too, as I just am unhappy with the whole process and cost with Testo of sending it back and calibration.
    For the Insight, I made a nice little app that I can shoot the QR code and put the combustion results on my phone and in my database.
    steve
  • SuperTechSuperTech Posts: 938Member
    My boss handles the cost of sending the Testo back every year for service/calibration. Maybe that's why he uses the Bacharach Insight? I've tried it and it's a good analyzer. I've also used one made by TPI, it was a less expensive option but gets the job done.

    One thing I don't like is how difficult it is to find replacement sensors for the 320. They use to sell a "self service kit" so you can do all the maintenance yourself, but it's no longer available. Makes me wonder if Testo is phasing out the 320.
  • SlamDunkSlamDunk Posts: 560Member
    I wish I had zeroed out the head. I will do that and everything else on next visit.

    The good news is, in similar time periods (Dec thru end of Feb) of last heating season and this one, the oil consumption dropped from 1380 gallons to 480 gallons!

    Had the burner been tuned better, consumption would have been lower than 480. Every drop counts!

    Old furnace was an Octopus gravity furnace that cracked.

    Thank you, everyone, for the encouragement! I don't do residential but the house is empty and my family needed help squaring this up.
  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,921Member
    @SlamDunk
    Good job I think your good to go
  • SlamDunkSlamDunk Posts: 560Member
    Sorry to bring this old one back but I have one more question.

    I was up this past weekend and furnace is working well, no soot build up detected, stack temp around 420f, but I noticed when burner extinguishes, the damper rattles no noise from burner, nothing shakes, just a clack from the damper. It didnt do this in February and i didnt bring any test equipment so i couldnt troubleshoot. I guess my question is, does it need to be troubleshot?
  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,921Member
    Barometric damper?
  • SlamDunkSlamDunk Posts: 560Member
    edited April 24
    Yes, a six, maybe 7" inch Fields. Dont have the model number but the weight is on backside of damper.
  • STEVEusaPASTEVEusaPA Posts: 3,083Member
    It’s probably fine as you describe.
    Does it do it right when the flame drops out or after post purge (if it has it)?
    Could be the burner is a little out of tune, provable with draft/smoke/combustion test.
    Could also be the damper itself. For a very important component, they are kind of flimsy in construction, could be a slight misalignment with the pins where it pivots-on the cheaper, standard models.
    steve
  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,921Member
    The barometric is going to move when the flame goes away. It's trying to regulate the draft. Burner goes off it's pumping a volume of products of combustion up the chimney then its stops suddenly, the draft has changed, the damper will move suddenly
  • SlamDunkSlamDunk Posts: 560Member
    Ok, that aligns with my gut feeling, I just never experienced it on the previous furnace, or even my own, old boiler. But those were both 10" flues. Thanks for the replies.

    There is a post purge and damper "clank" occurs when the flame extinguishes.

    I think I'll look for a better damper next time I go up to prep for next heating season. This model damper, what ever it is, was very difficult to find on line and I do no not like the counter weight being on the back side. My impression of it is it is the cheapest of cheap. Thank you again!
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