Any boiler maintenance/repair members?

Gregg

Gregg
Lifetime Supporter
I am hoping there is a boiler maintenance/repair member who can assist me. I have a Vaillant boiler with a Beckett AFG burner. Nozzle is 1.10 @ 80 degree B. I performed routine maintenance, changed filter, screen on pump, new nozzle, cleaned and adjusted electrodes, and disassembled boiler for cleaning- front plate, top spring plates and top side plates, flue pipes dissassembled, cleaned and reinstalled. Re-assembled without issue. Boiler starts quite and shuts down quite. Problem is that boiler starts quite, runs for about 30-45 seconds and then intermittently sputters. Flame is seen to momentarily go out and come back. Damper moves rapid with a little smell back into the house. I looked online for a possible solution but found nothing other than to seek out a licensed repairman. Tank is underground. Two pipe system. Only thing I can think of is possible blockage or freezing of water in the oil line, which I doubt, vacuum leak somewhere in supply line allowing air entrance, but I don't see any oil leaks to indicate same or possible pump failing to maintain fuel pressure. I don't think the air flow is an issue. Any suggestions to cure would be appreciated. Thanks in advance.
 
Gregg, if the nozzle is the type that is equipped with an integral micro-porous bronze filter, you may have a small bit of crud inside the filter that moves into one or more of the 'feed' grooves in the spray tip,even on a new unit. it may be congealed foreign matter. Try removing the filter from the nozzle assembly and cleaning/blasting the whole assembly,part by part with an aerosol can of brake cleaner. Spray through the filter from the outside in,same direction as fuel flow. Do not dry (touch) with a cloth,just re-install. Use ventilation when doing this. Also, the pump will/should have internal screen filters. Did you remove and clean them? If that fails, try roughing up the electrode tips with a file and then closing the gap ever so slightly. Be sure the tips are not in the main stream but just at the (upper) edge of the spray. You can check flow into the nozzle by opening the pump bleed or disconnect the line to the nozzle. In either case,use a small section of hose to redirect the flow into a container. Finally,go to the local Home Depot or Lowes and get a can of de-sludge liquid. Add per directions. A very small amount will treat a couple hundred gallons. A.J.
 

Gregg

Gregg
Lifetime Supporter
Doug & Al, thanks for the replies and suggestions.

Al, I performed all of those steps except adding the sludge remover, prior to posting. Today I even swapped the old nozzle back in. I will go to home depot and add the sludge remover and hope for the best. Thanks again, and if anyone else has any suggestions not mentioned, they would be appreciated.
 
If the desludge compound fails you most likely have an airflow problem. It may sound silly but check the flue/chimney for blockage. The soot builds up rather quickly and must be mechanically removed from the flue. DO NOT use a chemical to 'burn out' the residue - you're asking for a chimney fire. The other end,the air intake must be set set correctly as well. You probably have an adjustable slotted collar on one end of the pump/motor assembly that regulates airflow. This, along with nozzle size,regulates the air/fuel density, much like a carburetor.If you haven't touched this since initial setup, don't. If the combustion rumbles,it's probably too rich and can extinguish the flame if too violent. The other extreme,too much air/lean can damage the heat exchanger.A lean condition may appear to be 'surging' but without rumble. A professional can diagnose this by taking samples at the furnace exhaust/flue. He will check for correct hydrocarbon ratio and it's worthwhile to have this done. You'll save damaging the furnace and the cost off excess fuel as well as eliminating soot buildup in the chimney. I'm assuming you're asking all of this of this to avoid having the furnace guy come over, so try and judge proper,smooth operation by examining the flame in the chamber as it runs,that's all you can do. The last circumstance is that you got a crappy load of fuel that has contaminents or water. Fresh filters upstream will take care of the particulate and the desludger will disperse a small quantity of water. Let us know how you do. A.J.
 
Last edited:

Gregg

Gregg
Lifetime Supporter
Thanks Al. The flue is clean. I was tired of paying for the service contract by way of higher fuel prices, so the one year I don't take it, an issue arises. I'll wait and see what effect, if any the de-sludger has. I haven't touched the air settings and don't think it has ever been adjusted since I am in the house, and since I don't have the guages to test the system, I am reluctant to adjust the intake. The burner runs nice and quiet it just has an intermitent stumble so I think it is either a small vacuum leak or dirty fuel. The filter was filthy when I changed it, so it may just be bad load of gas. I might just add a racor water separator to the system this summer. If the problem persists, I'll have the furnace man analyze the flue gasses.
 

Gregg

Gregg
Lifetime Supporter
Al, at the suggestion of the plumbing supply store, I bought a vacuum gauge and tested the system. Vacuum was too high. Cause of the problem was then diagnosed to a partially clogged fuel supply line. Purchased a chemical clean kit and "Larry" the plumbing supply counter person was kind enough to loan me his CO2 pressure setup (approx. $150 rig) to blow back the line to clear it. Boiler is running now without issue. Thanks for your assistance and to all others who sent me a message.
 
Good to hear you fixed it. Remember to check the tank filter on installation to see that it seats properly or that goop will do a repeat performance. Right about now (10 deg) I'll bet you're glad you got it corrected!
 
Back
Top