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yellow flames, combustion problem?

I have a customer with a Peerless gas boiler. I wne there on a service call for no hot water to Indirect water heaters because boiler Pilot light went out. Relite pilot light everything seemed to be fine. waited 5 mins and noticed flame went from blue to bright yellow ( Pilot only). Fired boiler and noticed flames were very yellow and burning very poorly. The burner tubes seemed to be clear, and I didnt suspect an isuue from them because pilot tubing was burning yellow as well. I asssumed gas valve was bad so I changed it. The problem is the exact same. My next thought would be to check the boiler sections for carbon buildup and also check the chimney. Not sure what else I should be looking for. In terms of gas sizing Boilers 20 feet from meter. Only gas apliance in house besides gas range. Doesnt seem like a pressure issue. Please help I cant sleep knowing how this boiler is burning in my customers house. Thanks

Comments

  • icesailor
    icesailor Member Posts: 7,265
    Gas Pressure:

    Did you check the gas pressure in the house, after the meter/regulator? Just because the gas stove seems to be running correctly doesn't mean that the building pressure is. The stove has its own regulator. It is possible that the stove regulator is compensating but the boiler isn't. If the pilot and the burner are the same color, I'd not be looking there if you have changed the gas valve.

    With oil burners? First, check the nozzle pressure. If it ain't right, it won't run right.
  • Tim McElwain
    Tim McElwain Member Posts: 4,482
    Did you take any combustion readings?

    Did you adjust the air shutters?



    Did you clock the burner to see if it is over-gassed



    Did you check gas pressure before the gas valve and after the gas valve?



    Do you have sufficient air for combustion in the combustion zone?



    Are you a licensed contractor?



    I would go back tonight and either shut if off or stay there until you figure it out or fix it.



    NEVER LEAVE EQUIPMENT RUNNING WHICH HAS THE POTENTIAL TO KILL SOMEONE. YELLOW FLAMES INDICATE CARBON MONOXIDE.



    I am going to take what you posted and try to help you out:



    have a customer with a Peerless gas boiler. I went there on a service call for no hot water to Indirect water heaters because boiler Pilot light went out. Relite pilot light everything seemed to be fine.



    DID YOU CHECK MILLIVOLTS ON THE PILOTS SYSTEM?





     waited 5 mins and noticed flame went from blue to bright yellow ( Pilot only). Fired boiler and noticed flames were very yellow and burning very poorly. The burner tubes seemed to be clear,





    DID YOU REMOVE THE BURNER TUBES AND LOOK UP INSIDE THE BOILER WITH A MIRROR AND BRIGHT LIGHT?





     and I didnt suspect an issue from them because pilot tubing was burning yellow as well. I assumed gas valve was bad so I changed it.





    THE PILOT ON ALL GAS VALVES IS ON LINE PRESSURE ONLY THE MAIN BURNER IS REGULATED. TYPICALLY A GAS VALVE WILL NOT CAUSE THE PROBLEM YOU ARE HAVING. PUT THE OLD VALVE BACK OR EAT THE VALVE AS YOU CAN'T CHARGE THE CUSTOMER FOR A WRONG DIAGNOSIS/



     The problem is the exact same. My next thought would be to check the boiler sections for carbon buildup and also check the chimney. Not sure what else I should be looking for. In terms of gas sizing Boilers 20 feet from meter.





    THE FACT THAT YOU HAVE A METER ALLOWS YOU TO USE THE TEST DIALS AND WITH A STOP WATCH AND THE BURNER RUNNING CLOCK THE BURNER TO SEE WHAT IT IS BURNING. THIS WILL TELL YOU ALONG WITH A GAS PRESSURE TAKEN AFTER THE GAS VALVE IF YOU HAVE EXCESSIVE PRESSURE OR ARE OVER FIRED DUE TO WRONG SIZE ORIFICES (I ASSUME THIS WAS RUNNING OKAY AT ONE TIME SO ORIFICE SIZE IS A VERY REMOTE POSSIBILITY) IF YOU DO NOT KNOW HOW TO CLOCK THE BURNER AND DO THE MATH LET US KNOW HERE AND WE WILL HELP YOU WITH THAT.





     Only gas appliance in house besides gas range. Doesn't seem like a pressure issue.



    DID YOU BRING ON THE RANGE AND THE OVEN AND CHECK FOR CARBON MONOXIDE?





    Please help I cant sleep knowing how this boiler is burning in my customers house. Thanks



    YOU WILL SLEEP MUCH BETTER IN THE FUTURE IF ANYTHING THAT IS UNSAFE YOU EITHER FIX IT OR IF IT IS UNSAFE LEAVE IT OFF. 



    Let us know how you make out.
  • JohnWayne
    JohnWayne Member Posts: 31
    things to check

    Do you have a manual for the equipment your working on?  Most of the time the company will post their IOM manuals in pdf online.  Do you have a monometer?  I prefer a U-tube, but your digital might be sensitive enough.



    Check to make sure your getting the proper draft through the equipment.  Also is it a forced draft or natural draft.  If forced make sure your fan is spinning in the proper direction!!!



    Check the incoming gas pressures.  The manual should also tell you how much pressure you should be supplying to the unit.  Is your regulator at the unit set up right?  Are you feeding enough gas to the regulator? Are there any valves partially shut near by.  Next I would go to the meter like the others have suggested.  You need to test the incoming gas pressure to the building.  It should be enough to feed both the boiler and the range stove at the same time.  Make sure that when the stove or boiler is on that your can see the dials on the meter actually turning.  Sometimes meters will hang up and cause a low/no flow scenario.  If you find it's the meter you can call the local utility to come check it out, but make sure your right other wise you will have to eat the cost.  Check pressures on both sides of the meter to see if there is a significant pressure drop.  Good luck
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    If forced make sure your fan is spinning in the proper direction!!!

    We had that problem where I used to work. We had three very large main frame computers in the same computer room (the size of a small aircraft hanger). Two of them worked just fine, and one was flakey. They turned the A/C down to 65F and it did not help. This went on for months. Finally, someone noticed that the fans inside the computer were all spinning the wrong way.



    I had a similar problem with a desktop computer. It worked fine in winter, but flakey in the summer. After I checked everything else, I found out the intake fan in front was blowing out. The exhaust fan at the back, and the one in the power supply at the back were blowing out too. So the fans were maintaining a partial vacuum inside the box, and not cooling very well.



    Gotta check every fan, I guess.
  • Jim Davis_3
    Jim Davis_3 Member Posts: 578
    peerless Boiler

    A simple combustion test could have evaluated any possible problem with this boiler in a matter of minutes.  It can determine the amount of fuel(O2 & Flue Temp), venting problems(O2 & CO Stable), combustion air problems(Draft) or mechanical problems(High CO).  And of course a CO test would immediately let you know if you should shut it down on the spot before someone gets hurt.  
  • VictoriaEnergy
    VictoriaEnergy Member Posts: 126
    Look for...

    The 1st thing I'd look for " waited 5 mins and noticed flame went from blue to bright yellow"  would be contamination of the comb air with exhaust.  It can be responsible for the pilot outage too.



    Pilots full of crap will throw a yellow flame, but do it all the time.  Partially cloged flue passages won't usually bother the pilot when the burner isn't running.



    I agree with the others who are unhappy about you leaving an appliance burning like that.  As a minimum, you should have a CO detector and able to walk away from EVERY service call knowing the appliance is not producing exhaust with elevated CO level, and there in no measurable CO spilling from the installation.
    Home Owners Please Note:





    You are receiving advice from some very skilled pros completely free of charge. One of the reasons I participate is to sharpen my own troubleshooting skills. So; did we get it right? I would be grateful if you extend this courtesy back by posting the final outcome of the issue you are inquiring about. Thanks
  • VictoriaEnergy
    VictoriaEnergy Member Posts: 126
    edited May 2012
    Look for...

    Home Owners Please Note:





    You are receiving advice from some very skilled pros completely free of charge. One of the reasons I participate is to sharpen my own troubleshooting skills. So; did we get it right? I would be grateful if you extend this courtesy back by posting the final outcome of the issue you are inquiring about. Thanks
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