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delta Tdelta T Posts: 783Member
Went out to a boiler today (about a year old Lochinvar WHN155) to do a tune up and here is what I found on the combustion analyzer: CO 22ppm, CO2 1.2%, O2 19.2%. this was at full fire. at 20% fire, the CO2 does not even register, CO is less than 10 ppm, and O2 was 19.9-20.1%. boiler is condensing, neutralizer was full of water and the condensate line started running when I fired the thing. Venting is short, exhaust is about 20 effective feet, intake air is about 10. Natural gas, inlet gas pressure static is 8.2", 20% is 7.7" full fire is 5.5" so there is a substantial pressure drop on the gas but it should still be above minimum inlet pressure to my understanding. Gas pressure stays steady as a rock. unit is adjusted for high altitude (installed at about 6500 ft.) I tried to adjust the combustion, thinking that it just may not have been set properly on installation, and I could get the CO2 up to about 2% but the CO started climbing rapidly and once it got over 100ppm I decided to back it back down to where it was.

So, Gas piping may be an issue, this can be fixed fairly easily to abate the pressure drop, but my feeling is that it is not the problem given that it does not drop below 5.5" and is steady. Other than that, I cannot find anything at all wrong with the system. not short cycling, burner chamber was clean as a whistle, no errors logged, nothing out of the ordinary except the combustion.

Btw, the analyzer was calibrated a couple months ago, and I have used it on several other jobs and am fairly confident that it is working correctly, but I will never rule anything out.

Thoughts?

Comments

  • Tom_133Tom_133 Posts: 634Member
    Actually it's funny, I just received my Wohler back from calibration was still in the shipping box (thats how fresh) and I headed to 3 jobs that needed calibration or cleaning. Went to the first one a Lochinvar whn085 and for some reason I couldn't get the CO2 to rise, fought with that a while and it never came around. I thought thats weird I may need to get a rental analyzer. Went the next job a Baxi 380HT and proceeded to screw that thing up royally as well, before finally realizing I have a bad analyzer fresh back from calibration!! Sadly this will cost me a bunch of time, and next time I will not screw up more than one boiler!! So long story short it could definitely be your tool.
    Tom
    Montpelier Vt
  • JudySweetland_3JudySweetland_3 Posts: 120Member
    I agree with Tom, however have you checked the gas pressure through the valve. The 5.5" will be enough to the valve, but the gas pressure at the valve outlet should be checked too. IMHO
  • delta Tdelta T Posts: 783Member
    Yes I checked the gas pressure at the outlet and got the correct negative readings according to manufacturer.
  • delta Tdelta T Posts: 783Member
    Sorry I didn't get back to you all sooner, been crazy busy, but I found out what the issue was! I feel like an idiot, but the plug at the bottom of my meter for draining condensate was not properly snug, and thus my sample was getting diluted before it enetered the meter. * (smacks self on head) Thanks for the comments though everyone!
  • IronmanIronman Posts: 5,212Member
    delta T said:

    Sorry I didn't get back to you all sooner, been crazy busy, but I found out what the issue was! I feel like an idiot, but the plug at the bottom of my meter for draining condensate was not properly snug, and thus my sample was getting diluted before it enetered the meter. * (smacks self on head) Thanks for the comments though everyone!

    That's funny. I was was thinking about this post earlier this morning before I read it and that's what occurred to me was that you must have been sucking air in with your analyzer somewhere.

    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
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