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  1. #1
    Join Date
    Jun 2003
    Posts
    120

    Burner advice sought....

    Background: (I will try to be brief)

    September this year, called HVAC company to downfire Carrier oil-fired hot air furnace with Beckett burner. Was a 0.75gph and now is a .65gph. Reason for downfire b/c furnace is oversized and I wanted a lower fan speed for noise issues at the return.

    At time of this service, tech told me furnace ran great and efficiency tests,etc...were all good. (Barometric damper set at 0.04, see this for later)

    Come October, i started using furnace for first time and damper was banging back and forth when burner was on. I posted here on this forum, suggestion, call back company.

    So, I called them, tech came, said faulty nozzle. He "repaired" and said was running good again. I noticed later that the damper was now set at all the way to the left at 0.08 and that when burner ran, it did not open at all.

    In previous years with the 0.75 gph nozzle, the damper had always been set at about 0.04 and would open about 1/3 of the way and be very smooth in it's position. Never was it set all the way to left at 0.08.


    sooooo, now that it's been a few weeks and I am running furnace more, the damper is banging back and forth again; although not nearly as bad as the October visit, but at the same time enough that I know something is wrong. it seems to get better once burner runs a few minutes, but never as good as it was in previous years, not even close.

    So, here's the dilemma, do I call back this same tech who I now am questioning? The service I am sure would be free, but I don't know if he can do it.

    Or do I call the oil company who had been servicing my burner? This company always serviced it great. But I will have to pay them. I already paid $250 for the first guy to come out and do annual and also downfire and adjust fan speed.

    Or do I simply let it run rough and wait until next year, and call back the good company to do the service?

    Sorry to be so long, hard to explain whole situation briefly

  2. #2
    Join Date
    Feb 2008
    Location
    Massachusetts
    Posts
    702
    The only correct way to adjust a draft damper is with a combustion analyzer, any other way you're just guessing.

    The tech should have used either a digital analyzer or a wet kit, if no instruments were used to set up the damper, then most likely it's not correct.

  3. #3
    Join Date
    Jun 2003
    Posts
    120
    Quote Originally Posted by mlstark View Post
    The only correct way to adjust a draft damper is with a combustion analyzer, any other way you're just guessing.

    The tech should have used either a digital analyzer or a wet kit, if no instruments were used to set up the damper, then most likely it's not correct.

    he told me that he adjusted the damper using instruments. My question though is which of the three options should I do? Call back same company? Call new company and pay? Or just wait till next year?

  4. #4
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,805
    Have them put the right size nozzle back in.
    And reset the burner, and draft regulator back where they belong.

    Your flue temp is too low, and will probably soot up your furnace early. And cost you more to use.
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  5. #5
    Join Date
    Feb 2008
    Location
    Massachusetts
    Posts
    702
    If you're unhappy with the service you received, call the companies service manager and explain to him your concerns, and ask him if you could have it checked.

    In Massachusetts, whenever you do anything to change the air handling characteristics to the unit you have to do a combustion test.

    There actually might be nothing wrong with your unit, in the process of down firing your burner you also have to increase pump pressure accordingly,but this shouldn't make a noticeable difference.

    What beenthere has stated I have to agree, I'm not a fan of down firing, you should install the correct nozzle that the oem guide says belongs in the unit.

  6. #6
    Join Date
    Jun 2003
    Posts
    120
    Quote Originally Posted by beenthere View Post
    Have them put the right size nozzle back in.
    And reset the burner, and draft regulator back where they belong.

    Your flue temp is too low, and will probably soot up your furnace early. And cost you more to use.
    I was half thinking that myself. But which company? The same one that I had put in the smaller nozzle?

    Also, does the fan speed have to be put back to high? The current fan speed is med-high and it is barely slower than the high.

  7. #7
    Join Date
    Jan 2004
    Location
    PA
    Posts
    68,805
    Can't tell you about the fan speed. Since I don't know what your temp rise is, nor what that model allows for temp rise.

    Since the head of that burner may not be small enough for that nozzle. I would call the company that did the down sizing, and ask them if they check what retention head it has. And have them bring the firing rate back up.
    That way maybe they will have learned something.
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  8. #8
    Join Date
    Jun 2003
    Posts
    120
    Quote Originally Posted by beenthere View Post
    Can't tell you about the fan speed. Since I don't know what your temp rise is, nor what that model allows for temp rise.

    Since the head of that burner may not be small enough for that nozzle. I would call the company that did the down sizing, and ask them if they check what retention head it has. And have them bring the firing rate back up.
    That way maybe they will have learned something.
    Thanks for the advice. I will call them back.

    FYI, I looked inside the furnace and for the 0.75gph nozzle, it lists high or med-high as acceptable fan speeds. Temp rise is 55 to 85 degrees.

    Should I expect to pay the company again? I don't mind paying, I just don't want to pay if it's something I shouldn't be paying for.

  9. #9
    Join Date
    Jan 2004
    Location
    PA
    Posts
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    JMO.
    If the burner can't be fired that low without either a baffle plate, or a head change. And the company that did the down firing didn't do the change. Then you shouldn't pay.

    They may see it differently.

    Next time it runs. Take a thermometer, and see what the air temp is at the closet return and supply to the furnace.
    If your already doing a 70° rise, then it will need to be put back on high. Or the furnace will ride the high limit.
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  10. #10
    Join Date
    Jun 2003
    Posts
    120
    Quote Originally Posted by beenthere View Post
    JMO.
    If the burner can't be fired that low without either a baffle plate, or a head change. And the company that did the down firing didn't do the change. Then you shouldn't pay.

    They may see it differently.

    Next time it runs. Take a thermometer, and see what the air temp is at the closet return and supply to the furnace.
    If your already doing a 70 rise, then it will need to be put back on high. Or the furnace will ride the high limit.

    I measured tonight. I was out of house and heat was off, so when I turned it back on, it got to run for a good while. I also have the return directly above the furnace and the nearest register is very close as well.

    I measured 65 degrees at return and 130 degrees at the register. This is after running for about 15 minutes. So I am a 65 degree rise.

    The nameplate inside furnace says it can go to 85 degrees. I am hopeful that I can keep the fan speed as is and not increase it any. It is a little quieter now.

  11. #11
    Join Date
    Aug 2001
    Location
    Central MA
    Posts
    572
    You may not have an oversized furnace but you may have inadequate return(s). You need someone who knows how to size a unit and system to see exactly what you have. In some cases the noise is caused by more air than the duct can handle.

    Leo

  12. #12
    Join Date
    Jan 2004
    Location
    PA
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    68,805
    At 65° rise with the .65 nozzle.
    When switched back to the .75, if you leave your blower at the current speed, your temp rise will be roughly 75°.

    That doesn't leave a lot of room for your air filter to get dirty, but it gives it some room.
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  13. #13
    Join Date
    Jun 2003
    Posts
    120
    Quote Originally Posted by Leo View Post
    You may not have an oversized furnace but you may have inadequate return(s). You need someone who knows how to size a unit and system to see exactly what you have. In some cases the noise is caused by more air than the duct can handle.

    Leo

    The ductwork in my home is very small. My feeling is that even with the "high" speed on the fan, the ductwork is limiting the air volume and speed. It is a small 1 story home w/basement (unheated, but remains about 58 to 62 degrees in winter time).

    It is a combo problem of oversized furnace and also undersized ductwork. The company that installed it put it in very cheap, not sure why they oversized, but they did. And at the time I just didn't know ANYTHING about HVAC.

    Another of life's twists/turns for me. The one thing I got going though is that I am saving for a bigger home now, and when I do move, you can bet I'll be inspecting the Home's HVAC system and if it ever needs to be replaced, I will be doing a MUCH more careful contractor/equipment screening.

    but for now, I have to live with what I have.

    A small 57K BTU thermopride furnace and 1.5 to 2.0 ton AC would have been perfect. But I have a 105 BTU (input) carrier and a 3.0 ton carrier weather maker on ductwork that can just barely handle a 2.0 ton.......

    I am going to call company today and put back the .75, but keep the fan speed slower. I use those cheap fiberglass filters anyway, I'll just make sure to change every 30 days or even 25 days if need be.

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