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Boiler combustion test...

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Skyline
Skyline Member Posts: 152
I've been reading posts in this forum and service manual about boiler combustion tests have some question about this test.
During the last two years, I've overseen two combi-boilers installation; one is my own Viessmann and the other is my daughter's Lochinvar boiler. Neither of them had combustion tests as of yet.
Provided that I can find contractors who does this.... Should I schedule a combustion test for these boilers? And if I do and the values are not where they should be, will the contractor be able to make the necessary adjustments?

TIA...

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  • HVACNUT
    HVACNUT Member Posts: 5,865
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    Try to find a contractor who is familiar with your boiler if possible. A Weil McLain Ultra gas for instance has a maintenance kit, and not every tech knows that.
    A combustion test should be done at the time of the annual maintenance. 
    If the readings are outside of the manufacturer's (they all have their own spec's) parameters, adjustments are usually made at the throttle screw on the gas valve. 
  • Skyline
    Skyline Member Posts: 152
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    Thanks @HVACNUT....

    Finding the right contractor will be the hard part...

    The "throttle screw on the gas valve" is within the boiler, right? I wouldn't touch it, just curious...
  • HVACNUT
    HVACNUT Member Posts: 5,865
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    Skyline said:
    Thanks @HVACNUT.... Finding the right contractor will be the hard part... The "throttle screw on the gas valve" is within the boiler, right? I wouldn't touch it, just curious...
    You would definitely not touch it. It only gets adjusted if needed while the combustion test is being done. If for example the CO2 is reading low, then an adjustment is made in small increments to bring the CO2 level to the manufacturer's spec's. 
    The sequence of operation is pretty much standard on all mod cons, but there's so many makes and models out there, it's tough to familiarize yourself with all of them. My phone weighs 37 pounds from all the manuals I have downloaded. 
    EdTheHeaterManMikeAmannSuperTechreggi
  • GGross
    GGross Member Posts: 1,072
    edited January 2023
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    The newest series Viessmann have non-adjustable gas valves. You need to make sure your venting is proper and gas supply is correct. If the unit does not perform within spec they can warranty a gas valve or fan. They utilize a mass flow air sensor and modulating valve to adjust combustion based on needs
    SuperTech
  • Skyline
    Skyline Member Posts: 152
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    Thanks Guys...

    @HVACNUT.... It's interesting how the CO2 level adjusted by increasing/decreasing the the gas flow. Again, I certainly wouldn't touch it, but interesting. Sounds like you need a bigger phone, like this one...

    I used to have one similar in the early 80s...

    @GGross... My Vitodens 222-F, B2TB 125, had been installed in September of 2020. The boiler had two yearly maintenance performed by factory trained tech, it has no issues whatsoever. Well, if I discount the cost of the yearly maintenance and new parts for the boiler that is. I was just looking for, if I should add the combustion testing to this year's maintenance. Contrary to popular believes, the standard maintenance does not include combustion testing.

    When you state "newest series", do you have an actual date when it started. To my recollection, my boiler had been manufactured in February 2020 in Canada.

    Thx...
    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,124
    edited January 2023
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    my favorite wireless phone from the 60's.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    SkylineMikeAmannMad Dog_2
  • Skyline
    Skyline Member Posts: 152
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    @EdTheHeaterMan... Did you dial by the shoelace, or that was the antenna? :D
    EdTheHeaterMan
  • GGross
    GGross Member Posts: 1,072
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    @Skyline

    That boilers gas valve is not adjustable. A combustion test should still be performed during standard maintenance to confirm proper firing etc.
  • GGross
    GGross Member Posts: 1,072
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    @Skyline

    see attached from the B2TB service manual page 21. Where these are made it is required to perform a combustion analysis before and after every service. It might not be listed as "annual maintenance" in the manual for that reason, but it is specifically mentioned to be done before and after service


  • Skyline
    Skyline Member Posts: 152
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    Thx @GGross... That makes me question, if the techs who serviced the boiler actually have received Viessmann training, as stated by the contractor, and/or care much about the service manual.
    And people wonder why I dislike dealing with heating contractors...
    Disclaimer: present company is excluded, of course...
  • captainco
    captainco Member Posts: 796
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    What would be very interesting is to get the combustion readings from the contractor - O2/CO/Flue T and then we can determine if they really know how to do a combustion test and evaluate it.

    The fact that gas btus values vary in different parts of the country, makes not having adjustable gas pressure a bad thing. I believe the main reason is that manufacturers don't believe we are smart enoigh to do it!!
    Mad Dog_2
  • GGross
    GGross Member Posts: 1,072
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    @captainco
    This may be the only time I would disagree with you on anything combustion related.

    In Viessmann's case they definitely don't trust anyone to do it because the control is constantly adjusting the fuel/air mixture to meet varying fuel quality, as you mention the quality is different throughout the country. If the gas valve were adjustable the onboard combustion system would be useless, if the fuel quality changes the combustion changes and could fall out of spec or safe operation.

    I know not everyone agrees, but the technology is really cool to see in action. Anecdotally I go to many other boilers and find them burning way outside of safe operation, Where the Viessmann will shutdown and give an error code for service, generally prompting a tech to find an issue at the gas supply or with the venting that would have gone unnoticed with traditional equipment.
  • captainco
    captainco Member Posts: 796
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    I will admit I have never tested this Viessman boiler so what you say is somewhat correct. I got the trust part right. I have to admit that some of the mod-con burners out perform burners in the past. Having tested some other makes of mod-cons I have found some of these self-regulating controls operating like crap. The combustion numbers decide what good or bad. I would love to see these totally blow my mind!!
    GGrossMad Dog_2
  • Mad Dog_2
    Mad Dog_2 Member Posts: 7,113
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    Combustion analysis is very serious business.  Just because someone buys a $2000.00 analyzer, doesn't mean they are 
    Properly trained or are experienced in making the air/fuel adjustments. It took me a few years after Jim's (Captain CO) class
    And using it on EVERY boiler install and service call to be very competent and comfortable interpreting the data and tweaking the 🔥 burners.  I have also found selling testing is extremely difficult EXCEPT when there is a dangerous 😳 event, i.e., The Fire Department came or people got sick.  I always test my installs even hot water heaters but just include it in my price and do it for my own peace of mind.  Trying to convince people that aren't experiencing any tangible problems, is very tough and they look at you like a snake oil salesman. Their eyes glaze over and they yes you to
    Death and insist they are protected by their 
    Not so sensitive Store Bought Detectors or "my husband's a fireman we don't need anything."  

    Because the vast majority of contractors still don't use them, you seem like the alarmist CO nut.  I've learned to let those with a problem seek me out and came as a recommendation.   Mitigating CO conditions is very rewarding and fun work.
    Its easy to spend a whole day tweaking to find that sweet spot.  Unfortunately, most plumbers will not do this and most people won't pay for it.  Its one of things....reactive wins over proactive. Mad 🐕 Dog
    SlamDunk