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  1. #1
    Join Date
    Sep 2009
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    9

    central home oil heater, pump cavitating, what to do?

    I had to move the tank 3 feet further down towards ground. So, now the heater pump needs to pull fuel up 3 more feet. There was already a long distance from tank to pump. About 40 feet. The tank was at the same height as the pump. fuel got pulled up about 5 feet, over about 30, then down about 5 feet. Its been working like this for 26 years. However, I had to move tank down 3 feet. So, its now pulling up 8 feet, then over 30 feet, then down 5 feet. However, now it keeps cavitating. What to do? Last resort is to move the tank back up. Someone said a small low pressure automotive fuel pump mounted at the tank to push the fuel. This work?

    tks,
    pa

  2. #2
    Join Date
    May 2006
    Location
    Philadelphia, PA
    Posts
    1,391
    Most likely a leak. Your lift is only 3'. The 5' up, then 5' down balance each other. Has your contractor looked at it?
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  3. #3
    Join Date
    Sep 2009
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    Quote Originally Posted by comfortdoc View Post
    Most likely a leak. Your lift is only 3'. The 5' up, then 5' down balance each other. Has your contractor looked at it?
    I dont think a leak would cause cavitation of the oil.

    pa

  4. #4
    Join Date
    May 2008
    Location
    Missouri
    Posts
    3,535
    Good guess, there probably is a lot of sludge and rust in the bottom of that tank that was loosened when you moved it.

  5. #5
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    18,552
    Quote Originally Posted by wahoo View Post
    Good guess, there probably is a lot of sludge and rust in the bottom of that tank that was loosened when you moved it.
    While that could happen, I'm thinking that is not the likely situation. Older tanks that have a dip tube several inches above the bottom have developed a sedimentary layer that compacts and becomes pretty stable over time. You would have to be pretty careless in the moving, repositioning, and installation to get that stuff up into the dip tube. It is much more likely that this would happen if an unskilled guy installed a NEW dip tube, and stuck it INTO the sediment. A good contractor would flush the tank, properly install a new tube and lineset, and install the tiger as mentioned above. Since this may not be a contractor-supervised job, I'm thinking the best reason is a kink or crush somewhere, and a clogged strainer is the second possibility.

    Of course, in a cyber-diagnostic situation, we are all guessing. At a minimum, you can eliminate the line by exposing the connections at each end and see if the line is clear.

    I DO recommend a good contractor be used at this point, to cover all the bases, "live and in person."
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    2 Tim 3:16-17

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  6. #6
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    18,552
    Quote Originally Posted by paulmars View Post
    I dont think a leak would cause cavitation of the oil.

    pa
    I don't think a three foot suction head would cause cavitation.

    However, if you now have a restiction in your suction line, which could be caused during backfilling around the tank and lines, or during diptube replacement, then you could have cavitation.

  7. #7
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    Note:

    At 70 F, the Reid vapor pressure of #2 oil is .009 psia. If you can measure your suction line to that range of pressure, cavitation can occur.

    My sense of this is that you have a different problem.

  8. #8
    Join Date
    Jan 2003
    Location
    Northern VA
    Posts
    4
    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

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    Last edited by jpsmith1cm; 02-19-2013 at 05:32 PM. Reason: non AOP member

  9. #9
    Join Date
    Sep 2009
    Posts
    9
    I cant get any advice on which tigerloop to use. I cant afford a contractor.

  10. #10
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    Sep 2009
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    A restricted line might be the issue. Im trying to think of an easy way with my limited supplies to blow it out.

  11. #11
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    Nov 2006
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    Quote Originally Posted by paulmars View Post
    A restricted line might be the issue. Im trying to think of an easy way with my limited supplies to blow it out.

    Occam's Razor.

    Look at the line. It is unlikely that you have a sudden blockage that can be "blown out."
    [Avatar photo from a Florida training accident. Everyone walked away.]
    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  12. #12
    Join Date
    Sep 2009
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    Quote Originally Posted by timebuilder View Post
    Occam's Razor.

    Look at the line. It is unlikely that you have a sudden blockage that can be "blown out."
    Will looking at it clear it out?

  13. #13
    Join Date
    Nov 2006
    Location
    Southeastern Pa
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    18,552
    Looking at it will tell him if there's a problem with the lines, such as a kink, a spot crush, or some other damage.

    Occam's razor is the principle that the simplest explanation is usually the correct one. The OP just moved his tank.

    What is the likelihood that moving the tank has caused a clog in the line?

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