Strange issue, ironic it's Halloween?

Norm Harvey

Hello Folks,

   I came across a strange issue  that is stumping me, so I thought I would put it to you.

The particulars

    New Slant Fin Liberty w/ Beckett AFG, F4 head, 140psi, .85 70 B,

    New oil tank, new fuel delivery.



The problem:

   There is massive, and I mean massive impingement of the flame hitting the target wall, and the fire oscillates.   There is back pressure for a moment, then none, back pressure, then none and so on from the inspection door.



My troubleshooting

   Ive tried a variety of nozzle flow rates, angles, and spray patterns.  Even so far as to (as a test) Install and F0 head, static plate and baffle to reduce down to .50 gph.    I still have impingement even at that low firing rate granted less massive, but no good none the less.

  I have verified that while firing  the pump pressure remains constant at 140 ( I have also varied the pressure down to 100psi as a test)  This steady pressure allows me to rule out the fuel unit.

  I have verified a steady amperage draw on the burner motor while firing at 2.5 amps, and a visual inspection of the burner fan shows no oblong or out of round fan.   This allows me to rule out the burner motor/fan

  The Burner flange is welded, factory set insertion depth, so I can rule out blast tube insertion.

 

My hypothesis:

   If the chimney was somehow blocked, or partially blocked, I think I would get constant back pressure and not necessarily any flame impingement.  am I correct in this thinking to rule out a chimney obstruction?

   Beckett Technical support could only offer "A fuel quality issue" as a possible explanation, but the supplier that filled the oil tank, also filled his own tank the same day, and he has no issues.  I still can try running it off a can of diesel,  but I would rather go back to this house with more ammunition than a few gallons of diesel

   Given that this burner/boiler combination has been in production for many years, I am thinking that the poblem is situational to the peticular install  (This is not my install mind you.)

   I am stumped here as to the massive amount of flame bouncing off of the target wall, and the oscilation of the fire.





So,...

   any thoughts?



Thanks in advance,

  - Norm

Steamhead

Is this the 3-section Liberty/Intrepid?

These require a hollow or semi 80° nozzle with the AFG/F-head since the chamber is rather shallow. You may be getting eddy currents with the long, narrow pattern of the B nozzle, which might be causing the pressure variations. Also the factory spec is still 100 PSI. If you want to use 140 PSI (which is the same thing I'd do), try a 0.85x80°A and see if that works.



I grabbed the burner setup chart from Slant/Fin's site and posted it here. They now call the Liberty the Intrepid but it's basically the same boiler. And if you still have trouble, their tech department is quite good.



Also, how much draft did you measure?

JOE_104

liberty boiler

try .85 80 w @140psi makes for a tight white flame in this boiler