Oil Furnace Roar Comes In and Out

Discussion in 'HVAC Heating & Cooling' started by comahony, Dec 18, 2009.

  1. comahony

    comahony New Member

    Messages:
    4
    Location:
    Boston
    We're in the middle of a cold spell in the North East. I have an oil furnace. It is heating the water for the heating system okay. However, it is making strange noise.

    When the heating system is running, normally it makes a nice solid roar. However, now it goes back and forth between relative quiteness and the roar. (Almost as if its taking a breath.) The flame is solid and strong the entire time. And, as I said, there is hot water in the radiators.

    Does anyone have any ideas as to what it might be?

    I have a service scheduled for next week. Should I wait for the service, or should I get someone sooner? And do you think its okay to run the furnace?

    Any advice will be much appreciated...
    Conor.
  2. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    fluctuating draft conditions

    partially plugged - oil filter - pump strainer - oil line
  3. comahony

    comahony New Member

    Messages:
    4
    Location:
    Boston
    Thanks Peter.

    There is a faint smell (combustion) when you open the door to the basement. Something we didn't have before. The carbon monoxide detector is not at alarm levels.

    I do notice that the draft regultor door is open about as far as it can be. It is set to between -0.05 and -0.06. However, the draft regulator door is on top of the stack pipe. It is not a round draft regulator. The draft regulator door is at an angle of 45%, with the weight on the top part of the door and the opening at the lower end. And basically the door cannot open any more because the weight is against the ceiling (preventing it from going any further). For all I know, this could be how it normally operates. I haven't had any issues with this, so I've never paid any attention to it.

    Do you know what kinds of issues could be causing these issues? Should I consider calling a chimney sweep to see if there is a partial blockage?
  4. comahony

    comahony New Member

    Messages:
    4
    Location:
    Boston
    Two other things...

    1) The road is nice and steady when the furnace first fires up. It is only a few minutes later, that it starts to have these issues.

    2) Now, the door on the draft regulator is flapping when these issues start.
  5. nhmaster

    nhmaster Master Plumber

    Messages:
    3,189
    Location:
    S. Maine
    You will need a draft meter to check the draft while the unit is off and when it is running, both at the breech and at the chimney inlet but I suspect that you have a combustion issue, probably fuel delivery related.
  6. comahony

    comahony New Member

    Messages:
    4
    Location:
    Boston
    Hi,

    Thanks Peter for your help. I left this to the experts and got someone in today. Last night, I was mainly looking for reassurance that there wasn't a serious issue (and I wasn't risking the safety of my two babies).

    I wanted to follow up and let people know the resolution (in case someone else has the same issue and wants to know what it was). As Peter figured, it was an issue with the oil getting to the burner. It was actually a blockage in the line from the oil tank to the furnace.

    Conor.
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