Oil pump pressure test 2 line vs 1 line system

belham

Hello all,

Writing you from Europe. In my home, I've an oil burner (gasoil--called "mazout" here) made by Weishaupt and it is mounted into a cast iron St. Roch Couvin water boiler. Weishaupt is a renowned German oil burner maker, and essentially the unit is identical to Riello systems in the U.S. This overall unit was installed in 1998, and has been maintained every year. Some background before my question:

The 3000 litre gasoil tank is outside the house, buried about 6 feet down. At that height, it is at the same height as the oil burner sitting in the basement. The only lifting is drawing it out of the tank, maybe a 2-3 ft pipe and run 12-14 ft into the house (trenched under cemented/tiled floors) & into the Weishaupt burner. A two fuel line pipe system(3/8" copper) was installed, which leads to a Oventrop filter (attached to side of the Weishaupt boiler) that has a 100 micron filter in it. In 20 years, cleaning it every year, I've never seen debris and/or oil sludge in it.

The Wesihaupt utilizes Danfoss oil pump and Danfoss nozzles (nozzles replaced every 1 year, 2 yr max). The small fuel filter in the Danfoss oil pump is/was cleaned 3 times a year, since it is so easy. Equally, I have never seen debris there either in 20 years.

The system uses the chimney as its exhaust, as the chimney was closed off in all other parts of the house to set it up only for the oil burner machine. The chimney is regularly cleaned, and honestly, there's never really anything in it. Overall, the Weishaupt unit runs great.

I guess you are asking why I am writing/posting here then.

My problem has been for the past few years an increasing "after leak" at the nozzle. What started as a just a few drops every so often-- that previously the blower had no problem pushing back out the blower tube---has now turned into seeing a tablespoon of gasoil accumulating & leaking back down the burner tube. Unfortunately, there is no option on Weishaupt burners to adjust the burner tube down slightly towards the floor of the inside the chamber. Germans didn't make it that way because their units (cough, cough) are never supposed to leak.

Anyhow, I have ruled out overdraft (or the interior chamber getting blowback & the nozzle overheating), there is no oil seal leak on the Danfoss pump (it in fact the pump is brand new), it is not bad nozzles (all new ones leak too), all fuel lines hoses have been replaced, and everything (all connections) checked for being tight & sealed. What baffles about this nozzle "after-drip" is that the Danfoss pump fires right up, hitting its 10 bar, and the Weishaupt unit runs & purrs like a kitten throughtout its whole burn run (compared to other oil burners I have heard). Still, knowing I have a growing "after-drip" problem, I am in the process of buying a glycerin test and vacuum gauges to plug into the Danfoss pump for further testing.

This brings me to my question: is a two fuel oil line system different than a 1 line system when doing the pressure and vacuum testing? What I mean is, is on my 2 line system, should I still see the pressure test gauge (once it hits 10 bar quickly on pre-firing) should I see it fall no lower than, say, 8 bar and hold there (as I prevent the unit from fully firing)? And it should stay there, around 8 bar, until the next time the oil burner machine fires? Or does this pressure stuff only apply to 1 line systems, since in a single line system it has to hold at 8-10 bar no matter what, when off and/or on, always, versus a 2 line system that only pressurizes itself when needed (like when it is turned on) and thus never needs bleeding and/or worrying about "air" in the system?

Thank you for any help, advice and/or tips.