I have a 2yr. Old Riello (bf5) burner on a Peerles cast iron hot h2o boiler in my home. Lately it quits at night (3 nights in a row). To fix I: Reset, then bleed line once pump starts. There is a small amount of air that comes out immediately, followed by steady stream. It will usually ignite during this first bleed attempt and run fine until some point during the next night. :confused:

Tank is in basement. 3/8" x 20' line comes out top of tank, over head to boiler, down to shut-off and filter (right next to boiler). No visible leaks.

Q. Is there a check valve in the pump that might be failing vs.?

Q. Also, this being a completely new system, I only get 79% efficiency! Isn't this low?

add. info.
emission level = 12 co2
airate = 5
stack temp = 610 gross 550 net
nozzle = 85 80' B
smoke = 0

With an overhead oil line if there is a loose fitting the oil will syphon back to the tank. Also what brand of oil tank do you have? The eff. On the boiler is low, it is in the stack temp. the higher the stack temp the lower the eff. The CO2 reading is right on