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air in oil line

joe amadio
joe amadio Member Posts: 41
I recently relocated a 5 yr old wiel mclain gold oil boiler w/ a becket head from inside the kitchen of a levit home into the garage. I installed an above ground oil tank just outside the garage wall not more than 5 ft away. Its set up as a one pipe system with the feed coming off the top of the tank. The oil line is not more than 10 ft in total length.I have a standard general oil filter on it just before the gun. All fittings are flare. The customer keeps having to call for service because the unit is shutting down. Upon arrival the tech finds the gun in lock out and has to bleed the pump in order for it to fire. The amount of air is very little and it bleeds immediately. What I mean by this is is seems that the air is located in the pump. it takes only a second or two for it to purge. I've been told that a tiger loop is needed. But where is the air coming from? All connections are tight. Does any one have any experience with this situation?


  • STEVEusaPA
    STEVEusaPA Member Posts: 5,695
    Air can be tricky.

    Did you check with a vaccum gauge?  If you can bolt one onto the filter, or onto the pump, you should be pulling (4ft of lift=4, 1 for the filter, 1 for the shutoff, almost 1 for distance, oil safety valve?) almost a 7 (probably 5-7).  Remember, just because it's not leaking oil doesn't meant it's air tight.  Higher would denote a blockage, lower would be an air leak, or a crack in the line in the tank.  Also I would do all the usual pump checks-- check pump for proper pressure, pump cut-off, etc.  With the distance and the lift, no way you need a tiger loop.  It's probably just an annoying air leak.
  • Steamhead
    Steamhead Member Posts: 15,350
    I'd bet

    the air leak is at the oil shutoff valve or filter housing. 
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    I had an air leak in a Beckett burner once...

    I am not an oil tech. But I had a Beckett burner in an old GE boiler and it would work fine, but if it shut off for a long time, it had lots of trouble starting. It would fire a bit, and the fire would go out long enough that the flame detector would shut the thing down. Obviously an air leak, but they could not find it until the tech started pulling things apart. The oil pump seems to be like the one in a car engine; i.e., a gear pump with a relief valve after it. And the clearances between the gears and the sides of the casting prevented the oil from leaking back into the (below ground) oil tank. At least they did until the wear got too large. Two pipe oil system. He replaced the oil pump and all was well.

    I suppose leaks in the fititngs is the case here, but if the burner is old, it might pay to check the oil pump as well.
  • meplumber
    meplumber Member Posts: 678
    Well put JDB

    I went out on one myself about a month ago.  It is an old Beckett 1725 with a 1725 mini pump.

    5 callbacks to intermittent lockouts.  We had changed pretty much everything but the pump.  I put my gauges on and went to adjust the pressure, when I pulled the cap off, I found that it was leaking and sucking air through the seal around the adjustment screw.  I changed the mini.  Hasn't locked up since.  Maybe the second or third time ever that I had seen one lock up from a leak through the adjuster screw. 
  • billtwocase
    billtwocase Member Posts: 2,385
    can be two things

    one would be a restriction or obstruction. Do a vacuum test, but most likely your top of the tank fittings, and suction line would cause the air leak. Can you post pics, or show us how it is set up? That will help
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Mine looked like a Beckett AF, pretty much.

    It was new in about 1979., and was a flame retention burner. The original oil pump was a single stage, hooked up with two pipes, an oil filter, etc. It was replaced with a two-stage pump (I forgot just when, but I suppose around 10 years later) not because it especially needed one, but because that was what the tech had on his truck. That one lasted until 2009, and was probably still OK, but I converted to gas about then.
  • Greg Maxwell
    Greg Maxwell Member Posts: 212

    Was the original system 2 pipe?
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    Was the original system 2 pipe?

    It depends on how far you want to go back. The house was built in about 1950 with a brand new GE hot water boiler. Downdraft boiler, with supplementary air blown in the bottom. It had an in-ground 275 gallon oil tank with a single pipe to the boiler.. I bought the house in 1976. Soon after, the boiler would not run right due to excess water in the oil. The oil company pumped out the tank, but by the next day it had too much water in it.  At that time, that tank was pretty close to the house.

    That tank was inaccessable due to trees in the way, so they put the replacement tank (1000 gallons) far away (at least 50 feet away). It did not work well, so they hooked it up with two pipes. About the same time, they replaced the GE burner with a Beckett one and kept the two pipes. I forget the order of things, though.  This was all before 1980.
  • Greg Maxwell
    Greg Maxwell Member Posts: 212
    2 pipe

    Sounds like you took a boiler with a pump set up for 2 pipe and installed it into a tank, using only one pipe. What do you have on there for an oil pump?
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    No pump now.

    The boiler was this one:

    http://www.heatinghelp.com/files/articles/1025/177.pdf See the page with number 11 at the top right. My pdf viewer calls this page 10. And the next page too.

    Page 9 is the insides of a similar steam boiler, but mine was hot water.

    That one had a single oil supply pipe and no return. I do not remember if it even had an oil filter. When I had to replace the burner (the boiler was otherwise OK when oil was $0.40/gallon), I got that Beckett that had a pump that could do either one pipe or two pipe. They set it up one-pipe, but it could not get proper operation. I cannot remember just what the trouble was, but it would not fire. They took out some plug or something and ran a return pipe back to the tank and everything worked fine for 10 years or so.

    No pump now because converted to a gas-fired mod-con. There is a blower to get the gas/air mixture into the burner, but no pumps (except for some Taco circulators).
  • Ed N.Y.C.
    Ed N.Y.C. Member Posts: 73
    Air in oil line

    How far of the bottom of tank is line. 4" is normal. By running oil line this way you should have created a SYPHON. Once all the air is out of line you basicly have a gravity line.Plane and simple you have an air leak. Find it and problem will go away. Unit will run at 0" of vac. Hope this helps.  ED N.Y.C.
  • billtwocase
    billtwocase Member Posts: 2,385
    what Ed said

  • icesailor
    icesailor Member Posts: 7,265
    Air In Line:

    It has been my experience that on occasion, when connecting to the top of a tank with a one pipe system, micro bubbles in the oil will come out of suspension at the top of the loop at the tank and do this when the burner is off. Like overnight.

    A Tigerloop had always (for me) resolved this problem with no other modifications. The micro-bubbles end up in the Tigerloop and are eliminated.

    That's what Tigerloops are for.
  • Ron Jr._3
    Ron Jr._3 Member Posts: 603
    edited July 2011
    Hanging GE

    as they're affectionately called . It was very common to make the system 2 pipe when changing the original burner to a Beckett . They'd connect the return line of the new Beckett to the relief valve line that ran outside the plumbing wall . You had to drill and tap the top of the oil tank and connect the return line in . I work with an oldtimer that used to do these burner conversions . They'd send one guy out to do the whole job . Sometimes they had to throw in a new coil too ........

    I'll go with what Ed and Bill said . Suction leak somewhere . What type of oil tank did they use ? And I wonder how they ran the oil line into the tank itself ? Did they raise the boiler off the floor for the garage install ? If there's any fittings lower than the level of oil in the tank you should see oil if there's a leak . If there's a leaky fitting above the oil level , it'll show up as symptoms you describe .
  • Greg Maxwell
    Greg Maxwell Member Posts: 212

    I agree that the tiger loop is the answer.
  • yazoo
    yazoo Member Posts: 5
    the best

    is there compression fittings on the oil supply line, if so , trash them and use flare fittings with a little leak- lok smeared around the male flare end. could be suction gear capacity of the oil pump (wear), or as above stated, a small leak on fittings or seals on filter (general or fulflo) . if you can , incorporate a check valve at top of tank on oil line , this will create a slight restriction on vacuum readings , but could help. i have used a "liquid-eye" generally used in a/c and refrigeration to see if freon is bubbling and low, but  the liquid-eye can also show if there is a leak in oil under vacuum when the pump is  drawing.

    vince   [email protected]
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