Oil Burner Question

[howie]

I had a HVAC technician "friend" clean my boiler last fall and have had on and off problems ever since. My boiler is a 50 yr + old Weil-McClain with a beckett type oil burner. He replaced the tank filter and oil line to burner. He replaced the nozzle and cone. He said the existing ones were the wrong size. Once complete, he fired up the burner and bled the line. Once fired, instead of hearing the burner flame run constant and smooth, it kept intermittently flaming out every couple of seconds causing the damper door to bang shut every couple of seconds and stink up the cellar. He thought it was a draft problem and wanted me to get my chimney cleaned. About a week later I noticed it started running smooth and I let it go. A short time later it started running poorly again.

Since about February (I live in Maine) money has been tight and I couldn't afford to buy the 100 gal. minimum of oil and when I ran out of oil, I would buy 5 or 10 gals. of kerosene. Here is something I noticed. As I bled the line when firing up the burner, the air bubbles bled out and I got a nice solid steady stream of oil and the burner fired and ran nice and smooth. It's been that way for the last few months, no problems. I finally had 100 gals. delivered last week. I noticed when I went to bleed the line, air bubbles bled out but I never got a nice solid steady stream. The stream looked aerated and when I closed off the bleeder screw and the burner fired up it started intermittently flaming out again. I keep trying to bleed it but doesn't get better. Why would the stream of oil be aerated with 100 gals. in the tank and not when 5 or 10 gals. in the tank? Does it make a difference if it's kerosene or fuel oil? Anybody??

[HayZee518]

Could be water in the line not air bubbles. Kero or fuel oil floats on water. In the summer the difference in tank temperatures could cause condensation in the tank. Change the tank filter again and bleed the line. run some fuel out into a glass mason jar and let it sit for a while. water will condense out and you'll see the fuel floating on the water or it'll look like "fat globules" on the bottom of the jar.

[howie]

Thanks. I just ran some out in a jar. Will let it sit and see. Makes sense. The tank has been virtually empty the past few months and we have had a lot of humid weather lately. I will change the filter and bleed it again. Will post the results.

[suprheat]

Have your friend convert your one stage oil pump into a 2 stage and run the line back to the tank. This will allow the pump to prime itself and you won't have to worry about it. I was wondering what prompted him to change the nozzle type if it had been functioning properly for years prior?