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Correct Pump Pressure

Ok. Her I go. First time posting. Please be patient . I have a Slant Fin Liberty L20 Oil Fired with a Beckett Burner. Its a small Oil fired Boiler. It had for the longest time, a .75 GPH Solid Nozzle. I had plenty of problems with the nozzle clogging. This is what the boiler came with. I suspected that because the boiler was very narrow and the target wall was very close, the flame was hitting the wall and wrapping around. creating head pressure on the nozzle. So I decided to go lower with a .65 GPH 80 degree hollow nozzle. Since then, I had no problems. It takes slightly longer to heat the house but nothing to complain about. The nozzle has been installed all winter and summer. (I have a zone for domestic hot water.) Now its time for a cleaning and tune up. When I first installed the .65 nozzle, fuel pump pressure was 80 PSI. I left it alone. Specs call for 100 PSI. Since it is running fine, does anybody recommend I crank up the pressure to 100 PSI? It will hit the target wall more severely if I crank up the pressure. I don't want to cause more head pressure. I don't like the design of this boiler. The wall is too close to the nozzle. I have had this for a good 20 years..


  • Paul48
    Paul48 Member Posts: 4,469
    edited September 2015
    What do your combustion analyzer numbers look like? Clogged nozzles are not the nozzles problem, it's improper oil filtration. I can't see how putting a nozzle with a smaller orifice solved your problem.
  • StephenPelosa
    StephenPelosa Member Posts: 20
    The boiler was serviced by a local company. Its a second house I own. I live 100 Miles away. The only reason I have this co. is because of convenience. In the past, Every time they service the boiler, they would have to come back and replace the nozzle. After the first replacement, it would go with out a problem for the whole winter. I just didn't like the fact that the gun with the .75 GPH nozzle would hit the target wall. It would actually wrap around the wall. Wouldn't that cause a head pressure with the nozzle?. I started with a brand new tank and boiler years ago and had this problem from day one. After replacing the nozzle with .65, (hollow) no more problems. I'm not the expert, just want to know, raising the pump pressure to 100 lbs. Going to have more problems?
  • Jamie Hall
    Jamie Hall Member Posts: 23,426
    In comparison with the oil pressure -- 80 to 100 psi -- any back pressure on the nozzle from the flame "wrapping around" would be trivial. As Paul48 said, nozzles clog because of inadequate filtration. Get that fixed first.

    Then... changing the oil pressure changes the firing rate. Will raising the pressure to 100 psi from 80 psi cause problems? Hard to say without being there! But it will surely require adjusting the air and almost certainly the draught. Don't do it unless you -- or your tech. -- have the correct combustion analyser and draught equipment to make the necessary measurements, and know how to use it right.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Steamhead
    Steamhead Member Posts: 16,888
    I wouldn't run that burner with 80 PSI pump pressure. Pressure determines how finely the oil is atomized- the higher the pressure, the smaller the oil droplets and the more surface area of the oil is presented to the incoming air. With oil of questionable quality, which a lot of it is these days, better atomization means a cleaner burn. Most recent burner specs use pressures of at least 140 PSI as a result.

    Looking at the Beckett OEM Spec Guide, it does say that your L-20 uses a solid nozzle. If I were working on that boiler, I'd first check the drawer assembly's (part that the nozzle screws into) position relative to the burner head. Misalignment here can change the shape of the flame.

    Then I'd make sure you had a good filter in the oil line feeding the burner. Dirt and sludge in the oil will clog a nozzle, so feeding the burner with clean, filtered oil is a must.

    Then I'd set the pump pressure to 140 and install a 0.60x80B nozzle, which would give a firing rate of 0.71 GPH, and check the flame pattern. If the flame was still hitting the target wall, and the target was still firmly attached to the back section, I'd switch to a semi (W) or hollow (A) nozzle, whichever gave the best combustion test results without hitting the target wall.

    Obviously no one should attempt the above without the right tools and equipment. Where are you located?
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Bob Bona_4SWEI
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    I suspect by your terms "clogging/head pressure" you are referring to poor over fire draft and baking carbon on the nozzle exterior particularly on shut down. I wonder how the air tube/retention head looks, and what are the draft readings. If the ticket says "-.02, -.04" I would LOL, hard.

    Liberty's had a real shallow combustion chamber. Flame impingement could happen if set up wrong. Never EVER run an oil burner at less than 100 psi, Steam head is correct, boosting the pump to 140 will benefit and bring the fire in closer to the front.
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    ...And mark the new pump pressure somewhere obvious, (on the burner) so the next guy doesn't think you're underfiring, and puts the original spec (now too big) nozzle back in (and creates new and worse problems).

    There was an error rendering this rich post.

    Bob Bona_4RobGZman
  • StephenPelosa
    StephenPelosa Member Posts: 20
    I thank everyone for their comments. I am certainly no expert. I will take all this in. What I am going to do is clean the boiler, replace the filter,replace the nozzle with a .60 GPH 80A. Crank up the pressure to 100 PSI.Put the analyzer on it and check the readings. Most likely will have to add more air.. Thanks!
  • SWEI
    SWEI Member Posts: 7,356
    What type of filter is currently on the burner?
  • StephenPelosa
    StephenPelosa Member Posts: 20
    The filter is a General 1A-30. The typical wool filter with the canister
  • OuterCapeOilguy
    OuterCapeOilguy Member Posts: 46
    Steamhead, Bob and Steve are right on the money; 80 psi is WAY too low. 100 is the MINIMUM an oil burner pump should be set for. On many of my jobs, I reduce the nozzle size (gph) and increase the pump pressure, using the published tables. If the flame is hitting the target wall, you need a wider pattern. Also, the head spacing needs to be checked. As Hatterasguy said, lose that horrible General filter and install a Garber or PurePro spin-on (with vacuum guage indicator), and to that advice I would add, install a deaerator (TigerLoop or Sid Harvey Smart-Flo) together with flex hoses to the burner.