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High CO reading on gas conversion burner.

cwccwc Posts: 6
edited May 15 in Gas Heating
I've worked Google pretty hard and can't seem to find a situation like mine so remembering the help I got here about ten years ago I'm back with questions.

Recently the gas company installed a new meter and volunteered to re-light the pilot on my boiler. After lighting it they checked the gases in my draft hood and came up with 1300 ppm and rising for CO.

First I'll admit to ignoring this boiler for the last ten years or so because it made heat and didn't seem to use much gas.

The boiler is a Crane-line Midget with an Economite E20 gas conversion burner from Midco. My house is 1100 sq. ft. with a calculated heat load of about 32000 BTU/Hr. and is in southern Minnesota.

I checked the gas pressure and it was 3.5 inches of water which works out to about 132000 BTU/Hr

I looked at the nozzle and pilot assembly and it was pretty clean.

The blower had a fair amount of dirt on the vanes of the fan and in it's housing so I thoroughly cleaned it and put everything back together.

I replaced the 90° elbow attached to the output of the boiler because it looked like this.



I then fired the system up and adjusted the air shutter per the manufacturers instructions for quiet flame. I can't see the nozzle, so don't know about the flame color at the nozzle.

I've spoken to a locally recommended HVAC company and they will come out with equipment to measure the CO as well as other gases but the owner told me all of his older people had retired and he didn't have anybody that would be familiar with my system.

Before I make the appointment I have a questions about the white powdery deposits in the combustion chamber:

1. Is the white stuff in the photo below normal?
2. Is the white stuff related to the high CO reading?



And finally, given the condition of the elbow shown above shouldn't I be dead if the CO is really high? In the winter I spend hours in the basement working on motorcycles etc. and my lift is less than 6 ft. from the boiler. I've never experienced any of the symptoms of CO poisoning.

Comments

  • ChrisJChrisJ Posts: 8,026
    I can't help with any of your other questions but, as long as the basement had plenty of air coming in from outside, and the flue had plenty of draft, no CO or any other combustion products should have been coming out of the elbow. Even with that huge leak in it. Under proper operating conditions, that elbow contained a vacuum, not pressure.

    What condition is the rest of the flue in?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

    Steam system pictures
    https://goo.gl/photos/ZgpNUTyckkmiEdAf9
    Central air project pictures
    https://goo.gl/photos/4JjnLStEq42sWsQo8
  • cwccwc Posts: 6
    ChrisJ said:

    I can't help with any of your other questions but, as long as the basement had plenty of air coming in from outside, and the flue had plenty of draft, no CO or any other combustion products should have been coming out of the elbow. Even with that huge leak in it. Under proper operating conditions, that elbow contained a vacuum, not pressure.

    What condition is the rest of the flue in?

    Thanks for the quick reply.

    The elbow goes directly to the damper hood which had some corrosion in it's bottom pipe so I replaced that pipe section. Above the hood is 10 inches of pipe and another elbow with an adapter to the lined ~20 ft. chimney all of which are solid.

    The chimney isn't blocked and looks pretty clean.

  • ZmanZman Posts: 3,341
    What temp is the boiler running at?
    How long is the typical cycle?
    Have you inspected the heat exchanger?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • cwccwc Posts: 6
    Zman said:

    What temp is the boiler running at?
    How long is the typical cycle?
    Have you inspected the heat exchanger?

    Normally in the winter the boiler is 130-140°F. On warmer days it sometimes doesn't get up to temp before the thermostat is satisfied.

    I've never measured cycle time and really can't now since it was 85°F today. I'm pretty sure the burner runs at least 10-20 minutes but I haven't actually timed it. Earlier this month when temps were 30-50° F the non-burning part of the cycle was many hours.

    There is no external evidence of water leaks. It's hard to see inside the combustion area so i don't know about that.

    I run it as a closed system. Wouldn't I have to add water often if there were leaks?

  • SteamheadSteamhead Posts: 11,160
    edited May 15
    I'll bet the flame from that E20 is striking the inside of the firebox- what we call "flame impingement". When this happens, the temperature of the flame is reduced, resulting in incomplete combustion and lots of CO.

    ISTR the Midget dates back to the 1950s or so, and it really was a midget, not unlike the Axeman-Anderson Olympia and similar units we've seen at trade shows:

    http://www.axeman-anderson.com/olympia1.html

    If so, it would have required a burner with a really tight, compact, well-controlled flame to obtain good combustion. I don't know what type of burner it came with, but it would have had to produce a flame similar to today's flame-retention burners.

    But the Midco E20's flame is anything but compact. It was intended to convert old coal boilers to gas firing. These had much larger fireboxes than we encounter now. If you put an E20 in a boiler with a compact firebox designed for a flame-retention oil burner, you'll get impingement and high CO. We've replaced a few E20s for that reason.

    If your Midget is in good shape, and it's not severely oversized (that 32,000 BTUH heat loss sounds low for that size house in that area, unless it's very well insulated) and you can't afford a completely new boiler, you might have the E20 replaced with a Carlin EZ-Gas burner. Use either the "9-slot" diffuser (burner head) or the "B" diffuser in that boiler, depending on which gives the best results. Your stack temperature should not be much below 400° F to prevent the flue gases condensing in the smoke pipe, which is what probably rotted out the elbow. And the CO should always be less than 100 PPM. Obviously the installer will need a digital combustion analyzer to tune the burner. Do not hire anyone unless they have and know how to properly use such a unit.

    Otherwise, it's time for a new boiler.
    All Steamed Up, Inc.
    "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.
    https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc
  • ZmanZman Posts: 3,341
    cwc said:

    Zman said:

    What temp is the boiler running at?
    How long is the typical cycle?
    Have you inspected the heat exchanger?

    Normally in the winter the boiler is 130-140°F. On warmer days it sometimes doesn't get up to temp before the thermostat is satisfied.

    I've never measured cycle time and really can't now since it was 85°F today. I'm pretty sure the burner runs at least 10-20 minutes but I haven't actually timed it. Earlier this month when temps were 30-50° F the non-burning part of the cycle was many hours.

    There is no external evidence of water leaks. It's hard to see inside the combustion area so i don't know about that.

    I run it as a closed system. Wouldn't I have to add water often if there were leaks?

    It sounds like you are running a non condensing boiler at condensing temps.
    The acidic condensate is eating the flue and perhaps the top of the heat exchanger.
    I would venture to guess that if you look at the top of the heat exchanger, it is plugged up, causing the high CO numbers.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • cwccwc Posts: 6
    edited May 15
    Zman said:


    It sounds like you are running a non condensing boiler at condensing temps.

    I think I didn't give you the temp you were asking for. The 130-140°F is water temp.
    I fired up the boiler and after about 10 minutes checked the vent temp by putting the thermocouple just below damper hood near the center of the pipe. It measured 350°F. there.



  • cwccwc Posts: 6
    Steamhead said:

    I'll bet the flame from that E20 is striking the inside of the firebox- what we call "flame impingement". When this happens, the temperature of the flame is reduced, resulting in incomplete combustion and lots of CO.

    ISTR the Midget dates back to the 1950s or so, and it really was a midget, not unlike the Axeman-Anderson Olympia and similar units we've seen at trade shows:


    I think the boiler was installed in about 1950 when the house was built and the conversion burner was made in the 80's if I decoded the date code correctly.

    I'm not sure what small is, but the overall unit is 28Wx32Dx36H.
    The area that the flame enters looks like a 5 gal. pail on it's side with one side partially removed and is lined with something that looks like it could be asbestos sheet. This "can" is 18" front to back and about 12" wide at the widest point.
    The boiler wall is about 5" from either side and 10" beyond the back.
    The 10" section behind the "can" has large openings on both sides.

    From cold start the the flame that I can see is bluish, but in well under a minute it turns yellow/orange as does the liner of the "can". I think it has looked like that since I bought the house in 2000.

    Are the above dimensions compatible with the Carlin EZ-Gas unit mentioned below.

    If so, it would have required a burner with a really tight, compact, well-controlled flame to obtain good combustion. I don't know what type of burner it came with, but it would have had to produce a flame similar to today's flame-retention burners.

    But the Midco E20's flame is anything but compact. It was intended to convert old coal boilers to gas firing. These had much larger fireboxes than we encounter now. If you put an E20 in a boiler with a compact firebox designed for a flame-retention oil burner, you'll get impingement and high CO. We've replaced a few E20s for that reason.

    If your Midget is in good shape, and it's not severely oversized (that 32,000 BTUH heat loss sounds low for that size house in that area, unless it's very well insulated) and you can't afford a completely new boiler, you might have the E20 replaced with a Carlin EZ-Gas burner. Use either the "9-slot" diffuser (burner head) or the "B" diffuser in that boiler, depending on which gives the best results.

    The boiler rating is 127 MTU/hr maximum which is a little below the presently 132 MBTU/hr set firing rate of the burner. The burner can be set as low as 50 MBTU/hr.

    What is the correct ratio of heat load to boiler capacity?

    Would lowering the firing rate help the CO problem?


    Comments inline above.
  • SteamheadSteamhead Posts: 11,160
    edited May 15
    I wouldn't make any adjustments to that unit without a combustion analyzer. If you do, you're guessing. CO is nothing to guess about.

    If your stack temp is 350°, you might be OK. Dropping the firing rate might lower the stack temp to an unacceptable level. Given the dimensions of the firebox, I'd say the E20 will impinge no matter how low you go.

    This boiler is physically bigger than the Axeman-Anderson one I've seen, but the E20 is still the wrong burner for it.

    @Zman makes a good point about water temperatures. This may be an issue especially if the system piping was sized large to allow for gravity flow. If the pipes feeding the individual radiators are more then 1/2", it may have been a gravity system. Larger pipes hold more water, and this means a lot of cold water will come back to the boiler, keeping the boiler temperature low and allowing the flue gases to condense.
    All Steamed Up, Inc.
    "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.
    https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc
  • EBEBRATT-EdEBEBRATT-Ed Posts: 2,043
    What @Steamhead said is the best advise your going to get.

    Co is nothing to fool with or guess at. You probably "survived" because of good chimney draft and a boiler with wide open flue passages.

    Get it fixed

    don't tempt fate
  • newagedawnnewagedawn Posts: 118
    that elbow you showed in pic looks to have flue gas condensation, should have a qualified tech do a combustion test and check over the system, please fix all the flue pipe also, its fairly cheap and is not worth playing with your life, please let us know what you find, thanks
  • captaincocaptainco Posts: 166
    White powder, corrosion, rising CO are all signs of flue gas spillage and improper venting. I am guessing because the house may have leaks the CO has not gotten high enough to cause serious health issues, yet! 350 degrees below the drafthood but above it the temperature might be 200 degrees and that would condense.

    Water heaters operate at 120 degree water 12 months a year with cold water coming in from the street and don't condense. Unless of course they are not venting. Operating a boiler at 130-140 degrees should be no problem. The problem is the burner, venting and combustion air. Really need someone with a combustion analyzer to come in and test. But be careful because they may not know what to do about it and recommend you just replace the equipment. Yes there is better, safer and more efficient equipment, but the one you have can be repaired.
  • Paul48Paul48 Posts: 4,158
    I disagree with the comparison of a water heater and a boiler, and then stating that running the boiler at 130-140 degrees should not be a problem. That would be the temperature to shoot for with a mod/con, to ensure it condensed.
  • JUGHNEJUGHNE Posts: 2,857
    A water heater is not a cold start boiler. The cold water coming in is mixed with the existing hot. If you have ever started a water heater from a cold start, especially something with over 300,000 btuh burner it will condense like hell, so much condensation will run down the flue(s) it will sometimes knock out the fire or hit the flame sensor. Once it is up to temp this will not happen unless there is a tremendous draw of hot water. FWIW
  • ZmanZman Posts: 3,341


    There are some top notch guys who are experts with conversions who have given great advise on the burner.

    As for the boiler condensing, low water temps will cause that exact flue damage. It sure looks and quacks like a duck....
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • cwccwc Posts: 6
    I appreciate all the comments so far and am considering what to do.
    If the CO problem is caused by impingement then even with a new burner I think I will need to fix the liner because there is a fair amount of exposed metal where the lining material doesn't cover the metal parts of the "can" as described above.
    Is it correct that impingement on the insulating material is OK but on the metal parts is not OK.

    I definitely plan to find someone with a combustion analyzer to evaluate the exhaust gasses.

    When I ask them what they use what equipment name should I listen for??

    Because this time of year is busy for me it may be a while before I have something to report or ask about.
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