Oil Burner Vacuum Question

katman · February 2

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 · February 2

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

You are just fine at 5 to 6” vac

EBEBRATT-Ed · February 2

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 · February 3

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

katman · February 3

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 · February 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 · February 4

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 · February 4

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 · February 4

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.