Oil burner loses prime

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  #1  
Old 05-06-19, 07:18 PM
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Oil burner loses prime

Itís happened a few times now that heating season has ended, so Iím passed thinking itís just a fluke. Iíve a Beckett burner on my hot water boiler. The boiler and oil tank rest on the same level, maybe 30 feet apart. It uses a single line system. The 3/8 copper oil line exits the top of the tank and travels overhead until it drops down along a steel column next to the burner. The tank is a Roth 400 gallon and is currently about half full. (I opened the top and confirmed this.)

The line does have one flare to fitting to flare connection above the tank. This was an anti siphon valve that was replaced because we thought it was giving too much resistance. It turned out to be a weak pump, but all that was many years ago.

So the burner lost prime a few times. Iím thinking since the oil level is a couple feet higher than the safety valve/filter/burner that there has to be a leak in the line. Iím thinking if there was a leak by the boiler, below the oil level, oil would leak out rather than air leak in. Does this sound right? If so, how does one go about finding the leak? I eyeballed the line and nothing jumped out at me. The line along the steel column looks a little green, but not terrible. The joint above the tank was tight. Iím thinking I could probably pressure test the line from the fitting to the safety valve, but what about from that fitting into the tank?
 
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Old 05-06-19, 08:12 PM
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Typically the problem is where the leak lets air in. It can be anywhere. It doesn't take much of a leak to let air in and the fuel doesn't come out. I think I'd start at that flare fitting.

Does the line go directly down into the tank or is there another fitting there ?
 
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Old 05-07-19, 01:02 AM
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There are no other fittings, at least I think not. I watched it being installed and I recall one line into the tank to that fitting about 2í above it.
 
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Old 05-07-19, 07:01 AM
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To prevent loss of prime use either a two pipe setup (supply and return) or a Tiger Loop (automatic oil deaerator). Roth sells one under the Afriso label. To me this was always preferable because it prevents floor noise when the burner's running.
 
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Old 05-07-19, 10:37 AM
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b,
As PJ mentioned, a leak can occur anywhere and most times it is small enough to let air in which breaks the vacuum and lose your prime. The leak does not have to be bad enough to physically leak oil. Any discoloration around your fittings is a good indication something is going on.

Another thing you might consider is installing a Tigerloop deaerator. It is mounted at the burner and it takes the place of a 2 line system and automatically removes the air instead of having to bleed.

I mention this because at 30 feet and feeding overhead, although within range you are putting some strain on your pump. The basic oil pump is a single stage which means there is only 1 set of gears that both deliver the oil to the burner and then deliver it to the nozzle.

Typically to do what you are doing in older times we would have used a 2 stage pump which has 2 sets of gears. One to bring oil to the pump and another to deliver it to the nozzles and use a 2 line system. Your single stage will work but will wear out more often.

For installations like yours a Tigerloop is almost a most.

https://www.supplyhouse.com/sh/contr...Text=tigerloop

Below is a sight that will give you some info on vacuum.
https://www.engineeringtoolbox.com/f...ps-d_1022.html

Not sure what your pumps limits are without knowing what you have but my guess is your close to limit.

https://s3.amazonaws.com/s3.supplyho...6-brochure.pdf
 

Last edited by spott; 05-07-19 at 10:54 AM.
  #6  
Old 05-07-19, 01:59 PM
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That 30 feet was a bit of a hand wave. If that is near the limit I probably should measure it. I did start surfing up tigerloop. It doesnít sound like a bad thing to have regardless. Itís not even much more money than a second copper line would be.

If I go that route, where would I mount it? Could it be screwed right to the side of my boiler? Are those flex lines worth it? It would be nice if I didnít have to disconnect the lines to swing the door open.

Then I would need to decide if I should get the one with the spin on filter. I have a firomatic filter on it now. Iím a bit concerned that they stopped making elements for it, though Westwood still does. I do still have several elements in my basement, probably a 4-5 year supply for me.

On on the other hand it was working fine the way it was for a dozen years. If I can just find the leak.
 
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Old 05-07-19, 03:52 PM
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You can mount it right on the side of the burner. It attaches right to your boiler casing. With swing out door the flex lines are definitely worth it. Much better than running a second line. You don't need to alter your pump and less chance of leaking or loose fittings and line.

Putting a spin on filter on it is good for convenience but if you're happy with what you have that's fine. They will always sell elements for them. There are too many around.

As those figures show for a single stage like yours you are looking to be under 6" of vacuum. That pump is pretty much made for gravity installations and not so much overhead, although a lot of installs are now going overhead it just wears the pump out sooner. For every ft of V lift you count 1"of vac. Then you must count the other side too coming to the pump. If you have 2 ft rise and 2 more down and 30 ft H that gives you 2 +2 + 3 = 7" of vac and your pump is rated for 6". It will work but will wear.

That's with 3/8 oil line. The figures are different for different size lines.

https://www.supplyhouse.com/Westwood...a4b31c8524ea76

Just my thoughts.
 
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Old 05-08-19, 09:37 AM
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So after thinking it over, Iím going to go with a Tigerloop with the spin on filter. I figured if the burner lost prime when Iím away, even if the wife is home, sheíd just call a pro, who would probably install this same thing anyway. As for going with the integrated filter, I just think it would make for a clearer looking install. It also lets me do half the job upfront, before taking it offline.

I think the best place to mount this is on the hinge side. I think itís better for the lines, and thereís a column in the way on the other side. The problem is the oil line currently comes down that column. Is there a reason not to run the line across in front of the boiler above the burner? What am I allowed or not allowed to do WRT routing the fuel line near the boiler? Are there any keep out zones? How does it need to be secured?
 
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Old 05-08-19, 10:53 AM
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b,
Not really any rules about oil line placement except common sense. The more direct and shortest route the better for the pump. Other than that it's what is best for you. I don't know your situation so pics would be helpful if you need a better explanation.

If you have to move the line is it possible to remove the line from the column and stay overhead and come down on the other side of the boiler. Just secure so it's safe.
 
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Old 05-08-19, 12:23 PM
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Thanks all. As long as Iím not violating any workmanship practices by routing the line across the front high, thatís the way I think I should go. Routing the line low or down the back wall would result in a longer run. And I envision if I were to drop the line down vertically on the opposite side of the boiler it would get in the way when cleaning time comes. The front side opposite the hinge is actually the closest to the oil tank, and would give the shortest run, but there isnít great access to that side of the boiler. I guess I could mount the unit to the column, but then what does one do with the flex lines when the boiler is in operation? Do I just tuck them under the boiler? Thatís why I was thinking hinge side is better.
 
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Old 05-08-19, 12:37 PM
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Only you know what works best for you. Just, as you say, make sure you have access for maintenance.
 
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Old 05-10-19, 05:33 AM
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So I picked up a Tigerloop and was reading the installation instructions. It shows I need a loop, about a foot wide about a foot tall, extending below the inlet from the supply. There is such a loop into my filter now and most installation pictures I see have this loop as well. What is it for? It seems like it would just add more line and with it resistance to flow.
 
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Old 05-10-19, 10:36 AM
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b,
They are called expansion loops and are mainly used on oil lines like yours as stress relief. We add them as a precaution in case the line gets bumped it will have some play instead of putting pressure right on the connection and it also makes it easier if you have to remove the line from the fitting or if you have to redo the end for some reason but is not required.

Just an example on youtube. You can google more

https://www.bing.com/videos/search?q...64D3&FORM=VIRE
 
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Old 05-11-19, 06:29 PM
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I did the install this morning. Thanks for all the advice. All went smoothly. I elected to route the fuel line around the back of the boiler and use the existing flare. I didnít know that I could do as good a job with that. I did install a vacuum gauge too. It shows a little pressure when off and maybe 1Ē of vacuum running. So far Iím happy with the results.
 
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Old 05-12-19, 11:12 AM
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Thank you for the update.
 
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