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    combustion analysis (71 Posts)

  • drhvac drhvac @ 9:48 PM
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    combustion analysis

    In the market for a combustion test meter. These things are expensive. Is anyone familiar with the fieldpiece SOX2? Its much cheaper than alot of the meters and seems to do what I need it to do.
  • icesailor icesailor @ 11:11 PM
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    Combustion Analyzers:

    You get what you pay for.
    If you buy a cheap analyzer, you may get cheap results.
    I never heard of the one that you are contemplating.
    Bacharach is having a deal now Testo may also be having one Wholer never seems to have one.
    Cheap tools go with cheap jobs.
  • Kal Row Kal Row @ 10:15 AM
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    love my Bacharach 24-8251 FYRITE INSIGHT

    i bought it on ebay - be careful - this one was actually sold to me by jonstone supply - all the big houses do this now to increase sales - (if u cant fight them join em)

    a quick search will show 1200 to be the going rate for the analyzer and printer (a must have) - i am very happy with the unit and - they have a good sensor replacement subscription program

    the next big diagnostic thing i absolutely need to have is an infrared thats gona cost me...
  • icesailor icesailor @ 11:55 AM
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    I bought mine from my Wholesaler for the same price you got it from on E-bay. I hope that you don't have a problem with it because E-bay is a bummer on Warranty service.
    Mine came with the printer, the inlet hose. printer paper, filters, the program for transferring data to a laptop and a DVD on how to operate it. Including case.
  • Kal Row Kal Row @ 10:15 AM
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    love my Bacharach 24-8251 FYRITE INSIGHT

    i bought it on ebay - be careful - this one was actually sold to me by jonstone supply - all the big houses do this now to increase sales - (if u cant fight them join em)

    a quick search will show 1200 to be the going rate for the analyzer and printer (a must have) - i am very happy with the unit and - they have a good sensor replacement subscription program

    the next big diagnostic thing i absolutely need to have is an infrared thats gona cost me...
  • SpeyFitter SpeyFitter @ 12:13 AM
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    Do NOT

    Cheap out on a combustion analyzer. If you're a contractor (assuming you are) you should be billing for everytime you use the analyzer - something along the lines of an instrumentation or combustion analysis fees. Not only to help you recouple some of the investment into these precision devices, but also to help pay for future calibrations and repairs.  I've used a cheap analyzer in the past and I got what my company paid for. Spend a bit more and you'll get more.
    Class 'A' Gas Fitter - Certified Hydronic Systems Designer - Journeyman Plumber
  • drhvac drhvac @ 7:28 AM
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    which one?

    Ok, that's what I thought, you get what you pay for. What models do you recommend? How is the Testo 360? And how do you guys incorporate higher fees? When doing a routine cleaning, you give the customer the option to have the combustion test for an extra cost?
  • tim smith tim smith @ 9:07 AM
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    Re: analyzers and options for clients

    It is not an option because it is part of a safety check besides energy efficiency. You have to incorporate the costs into you hrly fee.  Make sure to count on probably 300 - 500 yr for maintenance repair.  I just sent 3 in for service, 500 each for repair. Thanks T....o       Tim
  • Jean-David Beyer Jean-David Beyer @ 10:03 AM
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    As a homeowner, it seems to me

    that for a routine annual service, the combustion analysis should not be
    optional: it should be included in the fee for that service. I do not like it hidden in the hourly rate, though. I think the fee for a routine annual service should be $xxx, where xxx may be different for different systems. For a first-time call, this should probably have to be time and materials (including overhead and profit) because the contractor would not know what is required until he has seen it. But I have never run a service business, and do not know the psychological realities of dealing with customers.
  • tim smith tim smith @ 1:52 AM
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    Re: analyzer fee and hourly rate

    I never implied it would be buried in hourly fee it is just part of the makeup of hourly expense as all expenses in our buisiness are. Insurance is x, office expense x, vehicles etc etc etc.  That is what makes up our hrly charges.
  • drhvac drhvac @ 2:57 PM
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    not that easy

    I strictly work on gas units. When I look in the local advertisements, all I see is my competitors advertising furnace services between $35 - $89. And in there advertisement the home owner gets a 21 point tune up, its all a bunch of bs, check belt, check t-stat, check this, check that. None mention combustion analysis, because none of them do it. Its hard being the one guy going in there and saying your going to service there furnace for $200 - $300 when all they see is the prices above. And homeowners all say how they will pay the extra money to have it done right, but most of them are looking at the bottom line which is the price.
  • Jean-David Beyer Jean-David Beyer @ 4:34 PM
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    I have seen those adds too.

    When I get them in the mail, they go straight to the trash.
    When they cold call me, I hang up. I do not read the throw-away newspapers where their ads seem to appear.

    I have read the annual service requirements on my boiler and estimate it would take me half a day, if I had the proper equipment. I have watched two different contractors do mine. The first one refused to do most of the steps required and said he was only allowed 15 minutes to service a gas boiler. That is why I dropped that contractor and went to the second.  They send a technician and a helper. It takes them between 1 1/2 and 2 hours depending on what they find. They come prepared with a new igniter, a full gasket set, plus the usual stuff on the truck. I do have to be firm with them to get them to bring the combustion analyzer, and show them where the access to the exhaust stack is to insert the probe.
  • clammy clammy @ 3:34 PM
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    ombustion anz

    drhvac,i fully understand where you are coming from,i work on oil,gas and some LP and it is tough .I also see the ads you speak of .i took the plunge about 3 or 4 years ago and brought a e instruments CA .Each year i take a service contract cost about 500 bucks but gets it certified and fixes what ever is broken.I also understand that it is a tough sale with HO's being your the only guy talking about testing while every body else blows it off.The field piece unit is pretty much junk and in my view in not even close to any real CA a waste of money in the long term .If you don't want to spend a whole lot take a look at TIF they make a couple .I have a buddy who's company uses them and they are happy with them but i do believe that they are not cert, but the sensors are field replacable a plus.I gave up charging for CA testing got tried of the yelling and screaming over the extra charge so  i just charge more on jobs where i will be performing a combustion testing like increasing my rate .As whole my CA has not been a money maker more like a expense at least around here being different and talking about combustion testing on gas equiptment is a albatrose there are only 1 or 2 guys i know who do it and even fewer who would buy one and that includes most of the bigger companies they all state that it done at the factory and is unneccesary for field testing or adjustment .Very touchy and funny subject espically amoung those who blow big buks on flyers ,mailer and yellow pages adds and nothing on test equiptment or read glasses .Sorry for the rant but it burns my bottom.Peace and good luck clammy PS keep fighting the good fight and stick to your guns espically on testing .I know i sleep good each nite
  • Jean-David Beyer Jean-David Beyer @ 4:42 PM
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    The money some save by skipping combustion analysis

    should be spent on increasing their liability insurance. There could be quite a large judgement against the person servicing the equipment and killing the homeowner and his family because of CO poisoning. 
  • kcopp kcopp @ 5:20 PM
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    I have a Wohler 335...

    petty good unit, although I am told that it is discontinued because it does not work on Biofuel oil... not a problem for you. It is in line w/ what other have said about cost and annual service. I have had it about 2 years. I can't imagine not having one now. I just used it to set up my first conversion burner and I would have been completely screwed w/o it. Use that to your advantage... advertise that if they don't do the combustion test they put their customers @ risk.
  • Steamhead Steamhead @ 2:06 AM
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    Without an analyzer and the know-how to use it

    you're naked in that boiler room. That's not a pretty sight :-0

    And this is the usual result:
    "Reducing our country's energy consumption, one system at a time"

    Steam, Vapor & Hot-Water Heating Specialists

    Oil & Gas Burner Service

    Baltimore, MD (USA) and consulting anywhere.
  • ChasMan ChasMan @ 10:26 AM
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    I have the same meter. I bought it new 3 1/2 years ago. The O2 sensor gave up this summer. I have used it perhaps 10 times, never dropped,m always stored inside. I sent it in to be calibrated. The results I got back from Wohler indicated that the draft reading was out. Now when I test draft where I showed -.-02 before I show 0 now. Also, my Stack temps went up 100 degrees.
    Just Great.
    I know these things are more indicators than lab quality instruments but come on.
    I ordered a Dwyer 460 for draft.
  • icesailor icesailor @ 9:11 AM
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    Combustion analyzers/Liability:

    Where I work, there is an oil company. No one in the past, ever used Combustion analysis (CA) ever, except me, and my old Bacharach wet oil kit. A friend had an old Lynn kit I could use but every time I went to use it, it was broken and needed to be sent to Lynn. That's why I bought my Wet Kit.
    Today, this oil company does a large percentage of the oil servicing. When they started doing it a few years ago, they bought CA's for every truck and spares for when being serviced. The insurance company told them that if they didn't have proof positive from an electronic instrument that showed that when they left after servicing the equipment, and there was a freeze up or soot up, they would be on their own. Hence, the CA's. They leave a print-out of the combustion analysis results, stapled to the card of what they did. And a copy in their files for confirmation. Strong incentive to buy a CA. The LP suppliers, only one does service and repair, have no CA's.
    I bought my Bacharach "Insight" recently because I have so many customers now with LP gas. And never been tested. I drained a customers house Thursday and found the 2004 vintage HTP Munchkin 140 locked out on F10, going out more than 4 times in one run cycle, I've never serviced this boiler, I didn't install it. I did the indirect and plumbing, a "Heater" did the boiler and air handlers. I reset it and the vapor coming out of the exhaust had an odd color. I put my "Stick" in the outlet and had 380+ PPM of CO. The boiler came as Nat. Gas and had no conversion sticker on it. It had black electrical tape covering the air inlet to increase suction through the orifice that was too big. Someone found this as a solution I am told. Another project.
    When you take your vehicle to the dealer, the first thing they do is hook up the computer to do a diagnostic. They won't even consider working on the vehicle without the diagnostic test. And they charge you for it. First thing on the bill. No one complains.
    Those pictures that Steamhead posted, some of those are "Cold Start" oil boilers, but all either not serviced regularly, or else the "Brush And Buff" crowd was servicing them. "They did such a nice job, they even wiped the dust off the transformer." So says the customer.
    It takes a lot of time to clean and service this equipment. And gas is just as bad. You just can't see how bad it is. unless you CA it.
    My "Insight" has all field replaceable sensors that are already calibrated from the factory. A program to replace them, and you can re-calibrate them yourself with your laptop. If it works as advertised, it is one cool tool.
    Nice representative photos Steamhead. Thanks for posting.
    I've spent four or five hours cleaning up a mess like that where the unit had been serviced in an hour for years "by others".
    I've seen "Cold Starts" that do that in a year, no matter what you do to it. I've seen "Warm Starts" go five years and look not a lot different than when it was cleaned the first time.
  • croydoncorgi croydoncorgi @ 11:37 AM
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    Essential for H/E gas boilers

    A CA / Flue Gas Analyzer is essential for the great majority of existing high-efficiency gas burners (except the very few with automatic adjustment - and even those shoud be double checked with a separate instrument).

    If you don't get the gas / air mix spot-on, efficiency will go down and / or boiler life will be shortened due to excessive solid combustion products, hot-spots etc.

    And often a combustion quality check is a valid alternative to stripping down the burner assembly on most machines much of the time.  If it ain't broke don't fix it.  With reasonable gas quality and the burner set up right, a burner should be able to go 2 or even 3 years with no need for cleaning.

    Reading here about (eg.) Viessmann heat exchangers needing frequent cleaning with heavy duty chemicals sounds worrying.  Are they in fact set up right?  Or is piped gas in the US full of sulfur or whatever?
    This post was edited by an admin on December 3, 2011 11:38 AM.
  • drhvac drhvac @ 3:06 PM
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    You guys convinced me. I'm looking in to the Testo 327, anybody familiar? Question. If I had a 95% efficient gas furnace and hooked one of these meters to it, and found that numbers were off and it had to be adjusted. How do you make the adjustments. The fresh air is fixed because it is coming from the outside. The only thing that is adjustable is the gas pressure, right? What else is adjustable on these units to change the co2 and o2 numbers should they need adjusting?
  • Tim McElwain Tim McElwain @ 3:22 PM
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    Before you start testing

    you need training on gas/oil combustion and how to properly use the analyzer. As for adjusting gas Mod/Con boilers and furnaces you need training on each manufacturer's unit as they are somewhat different. These are not your grandfathers old equipment anymore. 
  • Jean-David Beyer Jean-David Beyer @ 2:48 AM
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    I do not know about gas furnaces, but for my gas boiler...

    I read the installation manual, and it tells me what to do. I would not diddle with the gas pressure because that is the regulator on the gas meter, and I believe the adjustment screw there is sealed. On the boiler, the gas comes in and goes to the gas valve connected to a venturi that mixes the gas with he air. The gas valve is set so if there is no air flow, no gas comes out, and the more flow, the more gas you get. In other words, it runs like an old fashoned gasoline carburettor. There is a little blower in there that pulls in the air; the speed of that blower is controlled by the system electronics board that considers outdoor air temperature, boiler supply water temperature, and g.o.k. what else. There is a mixture screw that can be used for adjusting the thing. Perhaps it is like an idle screw.

    If I had a combustion analyzer, all I would have to do is set the boiler to high fire, and adjust the mixture to get the right levels of CO and CO2. Once I got that, I would set the boiler to low fire and check that I got the right levels of CO and CO2 there also. The only trouble is if I could not get the right levels at both high fire and low fire. Since I have a professional come in to handle this, I do not have to know. I wish the manual did tell me, so I could check on the professional.
  • billtwocase billtwocase @ 3:27 PM
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    Testo 327

    Can't beat em. Like any other necessary tool relevant to your trade, you can't try to bill separate. The tester is checking your work and adjustments. It is a necessary evil, and should come out of your mounting profit account. i have seen guys charge new tools to an install, and that is just not right in my eyes. If tou are charging a customer for something, then it should be left there for their future use.
  • icesailor icesailor @ 6:25 PM
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    Tool Charge:

    If you need to chop up a floor, and you don't own a $1.000.00 rotary hammer, and you go to the local tool rental place and rent one for the day for $100.00, do you eat the $100.00 or do you charge for the tool rental. If you bought the $1,000 drill so you didn't need to go rent one, and the good one was out and the junk one was available as usually happens when you rent, don't you think you should get paid for the tool?
    When you go to the auto dealer, you don't expect them to give you the $2,500 analyzer that they charged you $100.00 to diagnose why your "Check Engine Light" is on.
    Anyone that says that they can do it without instruments and do it by eye, is lying to you and themselves.
  • billtwocase billtwocase @ 7:18 PM
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    tool rental

    If you need to rent a tool or something for that particular job, that is a charge that you pass on to the customer. If you buy it, and will use it on countless other jobs, I personally wouldn't charge for that. I own my own jack hammer/drill, and I need it to make money. Without it, they will hire someone who does. It's like charging to use your screwdriver on a job. It's part of your labor charge
  • icesailor icesailor @ 8:15 PM
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    That's the point.
    If you rent it, you charge for it. If you own it, you give it away. What's wrong with this picture?
  • drhvac drhvac @ 8:21 PM
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    problem with 327

    I'm really getting to like my combustion meter, and you guys were right, it really gives you piece of mind when you leave the job knowing everything is working the way it should. I can't believe I went as long as I did without it. My meter was working fine until yesterday. The O2 reading is staying at 21% during the test and not budging. It was working the way it should by going down to around 8% after the burner fired and held. I checked the condensate drain plug for tightness, and I made sure the hoses were connected to the filters ok. I think the problem happened after I changed the order the display was in, but that shouldn't cause this problem I think. Anyone with the Testo 327 have any idea what it could be?The meter is only a week old.
  • furnacefigher15 furnacefigher15 @ 6:31 PM
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    stuck at 21%

    Couple things
    1- hose connections( filter, probe, etc..)
    2- pump not running (maybe in hold or stop mode)
  • KCA KCA @ 3:23 PM
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    What about...

    Using an analyzer on an atmospheric boiler?  What are you able to do?

    :-)  Kca
  • Steamhead Steamhead @ 2:41 AM
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    It will verify

    whether the burners are operating properly- in addition to checking gas pressures, clocking the meter etc.

    I once tested a recently-installed atmospheric gas steam boiler that had all the hallmarks of a hack job- copper header, no main vents etc etc. CO was about 600 PPM air-free. Turned out one of the burners had somehow gotten knocked out of alignment, and the flame was impinging on the cast-iron. I seated it properly and that solved the problem.

    If you don't test, you don't know!
    "Reducing our country's energy consumption, one system at a time"

    Steam, Vapor & Hot-Water Heating Specialists

    Oil & Gas Burner Service

    Baltimore, MD (USA) and consulting anywhere.
  • KCA KCA @ 4:49 AM
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    I've got an atmospheric boiler

    that has a CO level of 2500....  Nothing to adjust...  Manifold is at 4....  Got me stumped..
  • icesailor icesailor @ 8:21 AM
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    Combustion Analysis-Gas Type:

    Are you using Natural Gas or LP? I see gas burners develop CO like this that come Nat. Gas that haven't been converted to LP.
    I found a Munchkin the other day that had never been converted to LP and was installed in 2004. No conversion stickers and inspected. It hasn't run properly since the install. I didn't install it.
  • Plumdog Plumdog @ 11:31 AM
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    Sooted or clogged Heat Exchanger

    Is a likely cause. Sometimes inspecting the bottom of the Heat Exchanger with a mirror will lead you to believe that it is not too bad, but opening the top will reveal clogged flueways. It will likely "Roll Out" pretty soon. I would clean it, verify correct orifice size, manifold pressure, and primary air openings. Blow out or wash the burners. Lint buildup will throw off your burn. After a good cleaning the CO readings usually drop way below 100.
  • drhvac drhvac @ 8:08 AM
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    figured it out

    why my CA was staying at 21% even when blower came on. There are 2 settings on the meter, oxygen % & oxygen air %. I had it set on the Oxygen air setting which basically is reading the Oxygen in the surrounding air. The Oxygen % is the correct setting.
  • drhvac drhvac @ 8:11 AM
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    KCA manifold at 4, I'm assuming your meaning the manifold pressure. Most manufacturers recommend 3.5, so that is 1 thing that would effect the CO. What about combustion air, alignment of the burners, or flue piping size?
  • KCA KCA @ 8:41 AM
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    It's a Laars

    Boiler and they recommend 4" at the manifold for NG...  The draft is .01 and Combustion air..  is fine with (1) 7" high to the outside and (1) low to the outside..  The boiler is 160000BTU input..  I'm at 7000' ASL..  Alignment of the burners....  Seem factory set OK..            I have a Bacharach Fyrite Pro meter...  Measures Excess air..  CO2 etc..

      Any help is well appreciated...  :)
  • Mark Eatherton Mark Eatherton @ 9:05 AM
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    Start with the basics...

    Is it derated for the actual altitude of operation? It should be derated 4% per thousand foot above sea level .

    4" w.c IS the proper setting, assuming that the proper orifi are installed.

    Are the burners clean? You have to pull them completely out and brush and vacuum them to make certain they are properly aligned on reinstall.

    Also, the heat exchangers on this style of boiler is extremely susceptible to fouling and plugging,and although you may have the necessary draft at the vent hood, but not within the combustion chamber . Also watch for a lack of combustion air. Blocked or partially blocked HXers are usually also seen with a sign of rollout at the combustion air intake zone of the burners.

    The HXer can be clean insitu but may have to be pulled and taken for a ride to the car wash... Depending upon how much abuse it has seen (dryer lint is killer).

    Clock it at the gas meter to make sure it is properly derated, clean the burners and the heat exchanger and you should be good to go.

    Good luck Kenny and get back to us with the final results.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
    This post was edited by an admin on December 17, 2011 9:08 AM.
  • furnacefigher15 furnacefigher15 @ 9:12 AM
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    teledyne co levels

    If this boiler was sooted at some point, there is a good chance the burners are warped, causing wild flame characteristics.

    Pull the burners and inspect. The warping is hard to see, but look at the slotted openings in the burner, they should all have same amount of gap and curvature, if they don't, that is the likely problem.

    Good luck
  • drhvac drhvac @ 11:15 AM
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    back to original topic

    What effect does to much excess air have on the combustion process, and how would you lower it if you had to much? Does it ever get to the point where to much air could create CO?
  • Mark Eatherton Mark Eatherton @ 11:26 AM
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    You really should take a good class....

    From either TIm McElwain, or Jim Davis.

    Excess air will carry off the heat you are paying for, and can be adjusted in a number of ways, but will require significant modifications to the equipment in order to bring the draft under control.

    Excess air can quench the flame, which can produce excessive CO in the flue gas stream.

    The more I learn about the combustion/draft control process, the more I realize I have a LOT more to learn and apply in the field...

    Good for you for taking the right steps to learn the whole process. Owning an analyzer is only part of the job. Understanding, and interpreting the results and knowing what to do to change parameters is just, if not more, important.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • furnacefigher15 furnacefigher15 @ 11:04 AM
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    like mark said

    Too much excess air can lower flame temperature resulting in less heat output per unit of fuel being burned.

    The primary object of combustion analysis is to prove safe operation of the burn, meaning acceptable CO production (ideally 0 ppm, but AGA accepts 400ppm max)

    Secondary purpose, and for me of almost equal importance is to get the burn as efficient as possible. And, the meter saying X% efficient is not what I mean. An efficient burn is one where the excess air is as low as possible w/o producing CO. Every burner will be different, but each type of burner has general targets to meet, if you don't have a spec provided by the manufacture.

    Adjusting excess air depends on what type of burner you have. The easiest to manipulate are power burners (like oil burners), and the most difficult are in-shot type (like on most modern gas forced air furnaces)

    Usually too much excess air will not create CO, but in certain situations, it can.

    CO is a byproduct of INCOMPLETE COMBUSTION. Incomplete combustion can occur for a variety of reasons.

    One of the most common causes of too high of excess air is excess draft. And causes of this will very dependent on type of appliance and category of vent.
  • KCA KCA @ 1:19 PM
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    How about adjusting

    It on an Atmospheric Boiler?  There doesn't seem like there are a lot of adjustment options.. 

      :-)  Kca
  • furnacefigher15 furnacefigher15 @ 5:01 PM
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    atmospheric burner

    Primary air adjustment depends on the burner. Most of the older ones gave some kind of air damper built into each burner to regulate amount of air into the venturi.

    Secondary air is dictated by availability of combustion air, and amount of over fire draft.

    Gas pressure is the easiest adjustment too make.

    .01 inches draft is on the low side.

    What were the other readings? Also Start a new thread.
  • Tim McElwain Tim McElwain @ 7:02 PM
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    Primary air which

    is the adjustment on the burner itself has really nothing to do with combustion analysis O2 reading it is simply to adjust the air/gas ratio to a 10% gas 90% air ratio for a soft blue flame not roaring or lifting on the burner, not flashing back into the burner. On most atmospheric burners excess air is controlled by the design of the equipment as long as doors and installation procedures are followed. The requirements for combustion air are for every 1 cubic foot of gas (1,000 BTU's) 10 cubic feet or air plus 4 cubic feet of excess air at the burner opening into the combustion chamber. Then add roughly 15 cubic feet of dilution air at the draft hood. Most atmospheric burners get up in the range of 50% excess air. Then compared to say a power gas burner replacing and oil burner we can adjust excess air and get it down into the range of 15 to 25%. Some of these burners can fire at 2% O2 and still be safe.

    Failure to put doors in place or properly install particularly boilers when elevating to deal with flooding issues are often the main causes of excessive excess air which lowers efficiency and can cause cooling of the flame which increases Carbon Monoxide potential. ANSI sets standard for CO not AGA which is an allowable air free of 400 PPM. This is really to high and we actually want to see under 100 PPM on Oil and Gas unless manufacturers specs state otherwise. A good dependable analyzer is your best friend on all of this as you can monitor O2, Stack Temperature and CO and based on those three along with draft have a pretty good idea of real maximum firing rate efficiency. Some analyzers have a NOX eliminator so air free CO readings will be lower with those.
  • drhvac drhvac @ 9:04 AM
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    I mainly deal with gas

    80% and 95% furnaces, along with atmospheric boilers and furnaces. And like someone said, the furnaces with the in shot burners are the hardest to adjust. Besides the gas pressure, what else is there? And a couple of other things i notice:
    I put in American standard furnaces, I looked at all of there their installation manuals, service facts, etc. None of them have anything on what the co2, o2, excess air, etc. should be. Theere is no mention of it anywhere.
    Is to much or to little draft have to do mainly with flue pipe sizing assuming there is no blockages. If the draft is to high how do you reduce it. Everything is fixed? thx
  • icesailor icesailor @ 9:56 AM
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    CA Adjustments:

    I understand what you are saying about gas adjustments. I have done only oil and we have total adjustments. The old gas I see has almost no adjustments. Now, with the newer stuff, there are no easy adjustments to be made. I see equipment all the time that has been installed by installers who wouldn't know a CA if they saw one.
    Oil guys should really understand draft. Some don't. I'm being forced into gas testing. I saw two 2002 Munchkins last week without the 925 controllers in a duplex. One was running 90 PPM of CO and the other was 400+. What to do?
    If it wasn't for Tim McIlwaine and others here, I'd be in a quandary.
  • furnacefigher15 furnacefigher15 @ 10:30 AM
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    draft too high

    If draft is too high, it can be reduced with the addition of a barometric relief damper.

    Generally speaking draft before any dilution air should be between -.02 and -.04 '' W.C

    In some situations there is not much else to adjust other than gas pressure, and flue design.

    I have heard of some people adding ball valves to the intake of non modulating 90% furnaces to regulate amount of fresh air being added introduced.

    As far as combustion targets, sometimes you need to call the manufactures.

    While combustion testing see where temp rise of furnace is (should be in range)

    adjust fan speed to get rise correct. (this will effect stack temp and efficiency)

    General targets for category 1 vented Natural gas or LP

    O2 - 6 to 9%
    stack temp 325 to 500 degrees F
    draft -.02 to -.04 '' W.C
    CO air free 50 or less is best below 100 OK (below 400 acceptable )

    Category 4 (high efficiency)
    General targets

    O2 - 6 -9%
    stack below 140 degrees ( 144 is condensation point)
    CO air free 50 or less best, 100 or less is good (400 is acceptable)

    power burners (non - condensing

    3 to 6% O2 (4 is Ideal for most)
    275 to 500 degrees F stack temp
    CO same as others, the lower the better 400 max

    CO2 operates in a direct relationship with O2

    CO over 50 indicates a problem, over 100 worse, over 400 remove your probe to prevent damage to the chemical cell in the probe.
  • Mike Kusiak Mike Kusiak @ 11:34 AM
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    Atmospheric representative combustion numbers

    Here are some representative actual combustion readings taken recently with a Testo 327

    Burnham series 2, (model 205)

    T stack 465F
    Eff  80.2%
    CO 2 PPM
    Excess air 50.7%
    O2 7.6%
    CO2 7.46%
    Condensing dewpoint 124.2F

    Old National (1950's) gas boiler 178K BTU

    T stack 447F
    CO 3 PPM
    Eff  81.5%
    Excess air 42.8%
    O2 6.8%
    CO2 7.9%
    Condensing dewpoint 127.1F

    Burnham ES2 high efficiency atmospheric

    T stack 266F
    CO 8 PPM
    EFF 85.9%
    Excess air 37.5%
    O2 6.2%
    CO2 8.24%
    Condensing dewpoint 127.9F

    In comparison, a gas power burner can burn clean with much less excess air:

    Gordon-Piatt dual fuel commercial burner at low fire

    T stack 290F
    CO 0 PPM
    EFF 86.1%
    Excess air 23.7%
    O2 4.4 %
    CO2 9.24%
    Condensing dewpoint 131.9F
  • KCA KCA @ 1:22 PM
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    Here are a couple of readings

    From atmospheric boilers...  What to adjust?

    Eff% 81.6
    CO2 2.9
    CO   240
    O2 - 15.6%
    Draft -.04
    Stack Temp - 185degF
    Excess Air - 262
    Air free  860

    Eff% 82.7
    CO2 - 5.4%
    CO - 2285  (Yikes)
    Draft - .01
    Stack Temp - 242degF
    Excess Air - 109.7
    O2 - 11.4%
    Manifold pressure - 3.66WC

    The CO in the raypac unit is wild...  I really could use some suggestions...

    All readings were done with a Bacharach #125 just calibrated....

    :-)  Kca
    This post was edited by an admin on December 26, 2011 1:24 PM.
  • Tim McElwain Tim McElwain @ 1:58 PM
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    Eff% 81.6
    CO2 2.9
    CO   240
    O2 - 15.6%
    Draft -.04
    Stack Temp - 185 degF
    Excess Air - 262
    Air free  860

    Eff% 82.7
    CO2 - 5.4%
    CO - 2285  (Yikes)
    Draft - .01
    Stack Temp - 242degF
    Excess Air - 109.7
    O2 - 11.4%
    Manifold pressure - 3.66WC
    Are these boilers copper finned tube boilers? If so they are susceptible to getting drastically plugged up and need a real cleaning if not already damaged beyond repair.
    Ignore the efficiency readings on both of them

    CO2 is too low way too low.
    CO air free way too high
    O2 and excess air way out of control. Did you take these reading with everything in place on boiler doors etc?
    The stack temp is too low and is probably producing condensate.
    Has this unit been cleaned at all?
    Did you take these readings after the unit had been running at least 10 minutes?
    What training if any have you had on combustion?

    CO is gone! Again has this unit been cleaned?
    O2 and excess air way out
    Stack temp is in the condensing range, anything below 275 will condense.
    I assume the rating plate calls for an outlet pressure of 3.5 so 3.66 is over fired most of the time. Have you clocked these burners at the meter to see what they are running at for input?
    This post was edited by an admin on December 26, 2011 2:00 PM.
  • KCA KCA @ 3:52 PM
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    Units are Copper tube...  Both units are rated at 4" typ...  Both units are approximately 12 years old.. and never been cleaned..  Neither unit is rolling out and pulling them apart to clean the Htex are real time consuming...  I've done many before...  I'll clean the Laars tomorrow and see what the new readings look like,,  I haven't had much training in combustion..  Not alot available except that I search online to self educate...  I'm trying to do that...  other than running the vent and adjusting manifold pressure there isn't alot to setting a atmospheric boiler up...  Both these boilers are P/S with Tekmar controls with injection...  Both radiant heat..  Both run at +- 110degf at 20degF outside because of the amount of tubing in the floors...  One uses the domestic as a buffer...  but thats another story... 

    After I clean the Laars I would expect that the CO would drop...  The Draft would rise?  and stack temp would rise?

      :-) Kca
  • furnacefigher15 furnacefigher15 @ 4:06 PM
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    Return water too low.

    You need to use a mix down strategy to get a hotter return temp over 140.

    Stack temp wont go up till water temp goes up. Draft may not rise till stack temp is higher.
  • furnacefigher15 furnacefigher15 @ 2:44 PM
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    Ditto everything Tim said.

    If i'm not mistaken laars and raypak use 4'' manifold as there norm.

    Like I said in a previous post, and as Tim just pointed out theses boilers soot up easily if not set up right, and take on damage easily as well. The burners are stamped steel, so they'll warp easily, and the copper fin design lends to quick sooting.

    These boilers also condense very easily if return water is not 140 or better, and the condensate, falls directly onto the burners cooling the flame, causing incomplete combustion, which causes soot and CO, and the soot build up will cause the heat of the flame to more or less reflect back down at the burners which causes warping, which will cause future CO.

    I've had a few of these, where I was called too late. Once the damage is done, sometimes the only fix is boiler replacement. I've spent hours upon hours to get a good burn after years of misuse to no avail.

    For the above reasons, I am not a fan of this type of boiler.

    However, when installed and set up properly from day one, these boilers are fine. The trouble is, they are rarely set up right. Part or the problem is that unlike mod/con type boilers for example the manufactures of the copper tube jobs do not seem to stress the importance of setup.

    I've found it to be extremely critical for copper tube boilers to have not only good water flow, but good and hot water flow. The use of a system bypass valve to maintain hot return water is crucial (especially in domestic and pool heating application).

    A cast iron, or fire tube boiler is much more forgiving to improper set up. They will soot just the same, but when the right tech comes along and cleans the boiler, then does a proper setup, the damage that was done in the past, stays in the past.
  • furnacefigher15 furnacefigher15 @ 4:14 PM
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    Eff% 81.6
    CO2 2.9
    CO 240
    O2 - 15.6%
    Draft -.04
    Stack Temp - 185degF
    Excess Air - 262
    Air free 860

    O2 too high
    draft is tolerable, but minimally high. ( i would leave alone)

    You may have the wrong orifaces for the boiler if the gas is at 4'' and the O2 is still that high.

    need more gas or less air to lower the O2

    CO2 will increase as O2 goes down
  • KCA KCA @ 2:04 PM
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    After Cleaning


      I cleaned the exchanger and the burners on this Laars 160 boiler...  NG..
    Water temp in +- 180degF at return...

    The readings are as follows:

    Item:            Was              Is Now..

    Man Pressure  3.6"WC       3.78"WC

    CO            160-240PPM      5 PPM   Wow what a change...  Better draft?

    O2             15.6%              15.6%

    Draft          -.04                   .03 - .08  (I don't understand this...)

    Excess Air  262                  268

    CO2           2.9 - 3.0              2.9

    Eff%          81.6                  79.6

    Stack Temp  185degF         215degF  with 180degF water in return both times

    Air free         860                  24   (What is this?)

    OK...  Doesn't seem to have helped to much..  did with the CO.. 

    Your experience is appreciated...

    :-)  Kca
    This post was edited by an admin on December 27, 2011 2:06 PM.
  • Tim McElwain Tim McElwain @ 4:42 PM
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    I am posting here most of

    what I e-mailed to you:

    Keep me posted and let me know if you have any questions. I have found that many times even after cleaning those boilers they do not recover very well. They are drastically affected over the years by airborne volatile organic compounds from the environment they are operating in, such as laundry rooms, hair dressing, wood working shops etc all putting various chemicals in the air which react with the products of combustion, the copper fins and the water vapor in the flue gases. All are a formula for disaster with these boilers.

    Did you clock the burner on the gas meter to see what it is actually burning? What is the full Model number and serial number of this unit?

    You will need to use the ½ foot dial on the meter; we will let the half foot dial do two complete rotations using a stop watch to time how long it took to do the two rotations. Let’s say it took 20 seconds to do that, we then divide 20 into 3600 (number of seconds in an hour) this will give us cubic feet per hour since the meter measures gas flow in cubic feet and burners are rated in BTU’s we need to convert to BTU. So 20 divided into 3600 gives us 180 cubic feet per hour, we multiply that times the BTU heat value of the gas which is around 1000 to 1075 BTU’s per cubic foot that depends or what they use in your area. For simplicity of math we will use 1,000 times 180 gives us 180,000 BTU’s what the burner is actually firing at for input.

    What altitude is this burner operating at? That has to be calculated if over 2000 feet?

    The oxygen is way out of what it should be (5 to 7 % on this system would be normal) this then causes excess air to be too high. The excess air would be around 30 to 50 %. That would give a CO2 of 8.5% top 9.5%. Your draft should be around -.02. On a tester you typically get two CO readings one is a contaminated reading the lower reading the other is what is called a CO air free which is always the higher reading that is your actual CO reading. Cleaning helped the CO it looks like but it will get messed up again if it is not cleaned up. Is anything missing such as doors or panels etc. Those missing would allow excess air to be high. Why was the gas pressure increased? What does the rating plate call for? Clocking the burner will tell us if you are over gassed which can cause these high readings on air. As I increase the gas I increase the size of the package which means more air required.

    The other thing is the stack temperature is extremely low it should be between 350 to 450.

    Are you taking these readings sufficiently into the draft to get down into the sections of the boiler? If you take them after the draft hood in the flue with this system which I believe has a built in draft hood the readings will be way off.

    If you can send some pictures showing the boiler, vent chimney connection and show me with an arrow the location of the probe to take your readings. If you are not way into the boiler itself with the probe you will get the high readings you have.
    This post was edited by an admin on December 27, 2011 4:44 PM.
  • Tim McElwain Tim McElwain @ 4:16 PM
    Contact this user

    KCA, I am assuming these boilers

    are both shut off and not running especially with those levels of CO.

    What is your location as training is available from my training center located in Warren Rhode Island. Also sometimes Jim Davis from National Comfort Institute comes to different areas with his three day program. We come at this from different approaches but we both agree on the final outcome and 95% of our procedures are pretty much the same. I certainly bow to Jim's tremendous knowledge of combustion and combustion related issues.
    This post was edited by an admin on December 26, 2011 4:49 PM.
  • KCA KCA @ 4:33 PM
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    Both were running and for a good amount of time..  Easily 30 minutes or so.. 

    I'm in Colorado Springs.. 
  • Tim McElwain Tim McElwain @ 4:48 PM
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    Those boilers should

    be shut off as they are unsafe!! DO IT NOW BEFORE YOU HAVE A TRAGEDY
  • drhvac drhvac @ 9:31 AM
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    I have learned alot just through our discussion and some of the webinars i have took. Unfortunately I'm not close to Tim Mclain, or I would take his class. Every class I have taken over the years, even going back to my Lincoln Tech days back in the 80's, no body every said anything about combustion analysis. Between that, and the cost of the equipment,  I think that is why the majority of heating contractors don't do it. I've read a couple of Dan's books on radiant heat that was very helpful. Is there any similiar books on combustion analysis that any body knows of ?
  • Tim McElwain Tim McElwain @ 11:35 AM
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    Dr HVAC

    I have the books you are looking for contact me at
  • drhvac drhvac @ 3:50 PM
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    training cont.

    Hey Tim, Is that the right email/website? I tried but it wouldn't go through.
  • Tim McElwain Tim McElwain @ 4:33 PM
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    That is my e-mail

    address it is not a website as I do not have a website. I sent you an e-mail so we should be connected now.
  • furnacefigher15 furnacefigher15 @ 5:47 PM
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    I'm glad to see the CO levels were able to be reduced.

    O2 is still very high. Where are you putting the probe?

    Should be before any draft dilution takes place.

    CO air free is a calculation that the meter does. CO air free is what ANSI cares about.

    CO air free = 20.9 (oxygen in free air) / (20.9 - O2 in stack) X ppm CO

    Example: 500 ppm CO @ 3.5%O2

    20.9 / (20.9 - 3.5 ) X 500ppm
    20.9 / 17.4 x 500
    1.201 x 500

    600.5 ppm air free
  • Tim McElwain Tim McElwain @ 9:52 PM
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    KCA is at 7,000 feet altitude

    so different rules apply.Table F.4 in NFPA 54 Equivalent Orifice Sizes at High Altitudes (including 4% input reduction for each 1000 feet.) Orifice size reduction starts at any altitude 2,000 feet or more.

    There is also the possibility of the readings being taken at the wrong location.

    When you have a built in draft hood you need to get the probe into the boiler sections in order to get correct readings. Your return water temperature is also high what is the operating temperature of the boiler? A 20 degree delta t should give you a return temp around 160.
    This should be giving you a stack temperature over 300 degrees.

    You drill a hole in the draft hood then stick the probe through the hole into the boiler other wise you are picking up all the air coming in through the draft hood (dilution air) this will cause stack temp to be too low and excess air high along with O2 incorrect. None of your readings are any good until you do what I am telling you.
  • dano415 dano415 @ 3:21 AM
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    fieldpiece SOX2?

    1.  The  fieldpiece SOX2 looks like a great deal?

    2.  I need to find out if the sensor is replaceable, and at what cost?

    3.  I honestly feel the, "You need to buy a Quality instrument when dealing with
    combustion analysis!!"  are company reps for the competition over priced O2 sensors?
    (I would really like to ban all Company Reps--period--from these boards)

    4.  Fieldpiece has deep pockets.  Why would they risk a lawsuit over a cheap meter?

    5.   A $200.00 meter is a great buy.  In two years it will pay for itself if your a DIY
    guy.  Plus you can fine tune your heat source more than once a year.

    6.  Bachyrach, Testo, and UEI need competition--badly. 
  • dano415 dano415 @ 3:21 AM
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    fieldpiece SOX2?

    If anyone knows about the sensor, and if it's replaceable please post.

    Oh yea,  I would love to read the post on the HVAC technician who built his own O2
    sensor out of a wide band  Lambda sensor?  I can't find the post. 
    This post was edited by an admin on December 28, 2011 3:27 AM.
  • drhvac drhvac @ 1:34 PM
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    more testing questions

    I went on a service yesterday. This furnace is approx. 4 -5 years old, its a horizontal  60,000 btu 80% in an attic. As soon as I looked at it, I saw a problem with the venting. A 4" elbow comes out of flue, goes up 1', elbows again, goes approx 4' into the bull of a 6"tee. The 6" pipe is coming from another appliance downstairs. Once it meets up with the furnace in the attic, the other side of tee elbows up and out the roof of the house. The fact that the furnace in the attic vents to the middle part of the tee instead of a Y where it would flow out easier is wrong. That being said here were my readings.
    stack temp 283
    co2 5.28
    o2 11.5
    co air free 6
    excess air 108.3
    eff - 82.7
    draft - 0.1590
    Obviously the draft is wrong, it should be negative, but is has been working like that for approx 5 years now with no problems. If that was an atmospheric burner, it would be backdrafting out of the draft diverter. I suppose if it was a real problem with this furnace, the pressure switch would be tripping? Thx.
  • Tim McElwain Tim McElwain @ 2:08 PM
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    I assume this is a

    fan assisted 80% furnace which gets its air for combustion from the attic, is that correct? If so technically it is a atmospheric fan assisted furnace. The top of the vent outdoors must be at least 5 feet above the top of the unit.  Units in attics sometimes have the same problem as roof top equipment as they can no develop much temperature difference nor height to get good venting. They are also operating with typically in the winter time very cold air for combustion which affects their operation.

    What was the point that you took the readings in relation to the furnace?

    The O2 and excess air are way out of sorts, the 283 stack temp is very close to 275 minimum before condensing and is probably condensing like crazy when the attic temperature drops.
  • drhvac drhvac @ 5:19 PM
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    point of measurement

    was about 4" after the 2nd elbow coming out of the furnace. The gas pressure was on the money. Yes this was taking attic air for combustion, and it wasn't that cold when I was there, maybe 45 outside, and the meter says it was 67 in the attic. This is what I don't understand, how could you correct the co2 and o2 readings? The only thing you could adjust is the gas pressure which is good. There is no control of how much air the unit pulls in.  
  • Tim McElwain Tim McElwain @ 8:28 PM
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    There are other things

    that can be done but this is not the place to discuss them. We cover these things in our courses and some things are better not discussed here in an open forum as people who are not trained may try them and they should only be attempted by those who have been trained and are experienced in such adjustments.
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