Oil Burner Vacuum Question

katman

Hi, have a question about normal oil burner vacuum when the pump is running.

I had a new Granby AGT installed with a top feed. It's about 3ft from the top of the oil line from the tank to the ceiling. Then it's about 13 ft to the burner and 7 ft down from the ceiling to the burner.

Tigerloop is installed with a vacuum gauge on the supply line. I installed a new Suntec A2VA-3006B oil pump with bypass plug installed and set the pressure to 140 psi. Nozzle is 1.10. Carlin EZ-1 burner.

When the pump is in pre-prime, I'm getting about 4.5" vacuum. When the burner fires up, I'm getting around 5.5" vacuum. I also notice that the dial on the vacuum gauge vibrates slightly on occasion.

Does these readings sound normal?

Thanks!

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EdTheHeaterMan

anything over 7” hg. vacuum we recommend a two stage pump

You are just fine at 5 to 6” vac

EBEBRATT-Ed

If your not getting any air to the burner and it fires ok then I think you are ok.

You might want to put a valve between the vac gauge and the oil line to "save the gauge" The pulsations may hurt the gauge over time. If that happens the gauge may lie to you

Big Ed_4

The vacuum should be "0" on your set up …. Assuming it falls to 0 at rest ?

katman

https://forum.heatinghelp.com/discussion/comment/1839838#Comment_1839838

Yes, it is 0 at rest, the rises to 4.5 during prepurge and 5.5-6 during burner operation.

I wasn't sure if these readings were normal. Burner seems to operate fine with no issues.

Thanks

Big Ed_4

The vacuum is from the resistance of the oil running through the Tigerloop . The gauge is on the suction side of the pump … It may be normal …

techforlife

Too much vacuum, something is clogged or bad gauge. Should install O.S.V. at tank to protect Tigerloop from pressure when filling tank. At that point vacuum should be 2 to 4 " vac. due to O.S.V. Pulsating gauge means air leak in suction line, period. Possibly not all was purged out at install.

katman

https://forum.heatinghelp.com/discussion/comment/1840017#Comment_1840017

Thanks. Everything is new including the oil line, all fittings, firomatic, tigerloop, and flex hoses to burner.
When I first started it up after the new tank install I bled the system from the bleeder on the pump.

I see that the tigerloop has bubbles on occasion when the burner first fires. See attached video in the zip file.

I have another gauge I can try that is liquid filled, so it might be more stable.

The pulsating of the needle is very slight, and it doesn't happen all the time.

I don't think I can have a clog since everything is brand new. Is there an easy way to test for and identify air leaks from the suction line?

This might be a wild goose chase since everything seems to be working fine. I just wanted to make sure everything was working normal since I never had a top feed oil line running across the ceiling and a tigerloop.

Thanks again everyone!

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techforlife

How far off the bottom of the tank is the new dip tube? It might be too long and sitting in the mud. If during install it was pushed to the bottom and pulled up, it may have sucked up some mud. The observed air bubbles may be coming from a weak fuel unit shaft seal.

katman

https://forum.heatinghelp.com/discussion/comment/1840100#Comment_1840100

I'm not sure how far from the bottom the new tube is, but the tank is brand new with fresh oil.

I also put on a brand new Suntec A2VA-3006B oil pump.

Thanks

katman

Here's some pictures of the oil pump lines, and a video inside the zip file showing the vacuum gauge vibrating:

20250204_112032.mov.zip

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katman

Update

Hey guys,

So I did the following:

Replaced supply and return flex lines out to TigerLoop brand lines

Changed out pump inlet brass elbow to a new 1/8"NPT M by 3/16" Flare M (not easy to find)

Changed out brass nozzle oil line from pump to nozzle

After this, I now read 0" of vacuum during prepurge and when the burner is running.

Hopefully zero inches of vacuum is a good number 😀

I did notice with the old flex line that the vacuum gauge needle would bounce when I wiggled the flex supply line - perhaps this is where the leak was.

Thanks again for all the help!

katman

Well that lasted all of two days….. vacuum is back to 4" when the burner is running, and the needle shakes when I shake the flexible suction line.

I'm going to put back on the original oil pump as a last resort, perhaps the new pump is bad.

EdTheHeaterMan

After watching the video, I dont believe that there is any problem with your system. That little bit of air that you see in the clear tiger loop top is normal. That is what the tiger loop does, it deaerates to oil before the pump see the air as a problem. If that little bit of air you see wound up in the fuel pump during burner operation, it may end up causing a slight rumble in the flame as the air went thru the fuel pump's pressure regulator.

Don't over think this. the bottom line is: does the burner heat you home? Are you trying to solve a no heat or noise problem or do you just want everything perfect? The new and the old pump are made to operate with a 4"hg. vacuum with out a problem.

The rule of thumb for vacuum is 1"hg vacuum for every 10 feet of 3/8" oil line and 1"hg vacuum for every 1 foot of lift

katman

https://forum.heatinghelp.com/discussion/comment/1844867#Comment_1844867

Thanks, everything works fine - burner has never operated better so I'm going to remove the gauge, put a plug in place of the gauge and leave it alone 😀

LRCCBJ

I don't think I can have a clog since everything is brand new. Is there an easy way to test for and identify air leaks from the suction line?

After suffering your exact issues for months, and finally correcting them without a tiger loop, the process is as follows:

Put the vacuum gauge back on the pump.

Start the burner and let it run for a few minutes. The gauge will read 100 psi (possibly more if it is setup higher).

Shut the burner down and watch the gauge. It will fall by about 15% upon shutdown. THEN it must hold that vacuum level (typically 85 psi or so) INDEFINITELY. If it falls over the next 10 minutes, you have a suction leak. Finding it and correcting it is an exercise…………..sometimes a lengthy exercise. You must redo the flare that has the leak. It's an iterative process…………with a bleed and a test after each attempt.