Vacuum gage on oil filter cansister

HyrdoAirJoe

Just had my annual maintenance on my oil fired boiler and the tech installed a vacuum gauge on top of the oil filter canister.  What is this gauge for and how do I interpret it's readings.  It does not move from 0 even when the burner is running.



TIA

Jean-David Beyer

I suppose it is to show if the filter needs replacing.

I suppose it is to show if the filter needs replacing. Or maybe to see if the oil pump is failing. It depends just where, hydraulically speaking, that gauge is placed. On the Input? At the Output?



It is puzzling that it does not read at all, even if the boiler is running. Should it run much in August?



If the gauge is not defective, perhaps it is not sensitive enough. When I ran oil, they routinely changed the filter every year (and the nozzle), so there was no need for a gauge.



And when my oil pump failed, it puzzled the tech for a while because the pressure was fine,  but the boiler would misfire when starting up. It turns out the clearance between the gears in the pump became too great, so when the boiler stopped firing, air was drawn back into the fuel supply, and the air kept the boiler from firing properly. He put in a new pump. I doubt a vacuum gauge would have found that problem.

Paul Fredricks_3

gauge

It is there as a diagnostic tool used by the service tech. They use it to check if the filter is plugged, or if the oil line is plugged, or if there is an air leak in the oil line. The readings will vary from unit to unit depending on many factors. A reading of zero is normal with a clean and clear filter and oil line. If that reading changes it does not necessarily mean there is a problem.



The best thing to do is forget it's there. It's really for the service techs to help them with troubleshooting. We've had customers call to tell us they are out of oil because the gauge reads zero.

chapchap70

Pressure Normally

Hi,



Where there is a basement tank, the oil is flowing by gravity if the burner is lower than the oil level in the tank.  If the filter is clogged, the oil burner pump will have to suck the oil and the gauge will register the vacuum.  If there is no restriction, there should be no vacuum and the gauge will read zero.



chapchap70

Jean-David Beyer

I forgot about that.

My tank was in the ground, and so far away (about 40 feet and 3 feet down to the top of the tank)  that I needed a 2-pipe system to get reliable operation. At one point I got a 2-stage pump in there too, but that was because the tech had only a 2-stage pump in the truck that day when I needed a new pump. So mine always pulled  a slight vacuum.