Afterburn

[chitty]

In dealing with a Hotsy 9450 boiler with a becket burner I have run into an issue.When the burner cylcles to off (discharge water to temp),I am getting blue white smoke from the chimney.( Afterburn old risidual fuel I'm assuming)
Electodes new,transformer strong,air settings ok etc.When the burner ignites it comes on instantly as soon as the fuel selenoid light indicates fuel to the nozzle with no hesitation, and burns nice and even. Intial puff when igniting comparable to a 5 gallon pail worth of smoke and burns clean from there until it shuts off.
I've dropped the burner assembly and test run laying on the floor outside ( burner not bolted into coil housing) the electrodes burn nice and blue/strong with good stretch when the fan blows through spark, the fuel tip sprays nice with good atomization.The fuel pressure set to spec. @ 125 PSI, air band and shutter adjusted to burn just off soot during ignition.Checked fuel selenoid function with the thermostat and it shut completely with no extra leakage when in the off position (not energized)
The coil is new 2 weeks ago and visual inspection today down the chimney shows no significant sooting of the coil enough to choke it out.
Spoke to hotsy dealer and they are at a loss and have nothing else to offer over what I did.Called the 800 line for becket burners and of course they are Closed for the day.
Okay guys....What's the deal with afterburn when all setting appear to be OK and the burner runs good when its running.??
I'm waiting on Z dimension settings for this model "HO-1601" unless you happen to have them kicking around in your head???!!!!

 

[MR ALAN]

How's your insulation? Maybe fuel saturated.

 

[Larry L.]

or could even be a weak battery,electrodes shutting a split second off first before the fuel turns off.

 

[aplanone]

Try this

Try adjusting the air band. If it is smoking white it is getting to much air.
It is normal to get a puff of smoke at start up.
If it is still smoking when the burner is off then it is loading up on fuel.

Good luck,
Ivan

 

[chitty]

Well that will teach me to overlook the obvious.
History is boiler was in a truck (2006 Kenworth Steamer) for a company I am working for recently and not my own.They had replaced the coil a couple of days before I started doing their boiler repairs.They went to acidize the old one and flowed it the wrong direction,plugged it right off and could not free it up.($2300 mistake Ouch!) Thier mechanic installed a new coil and could not get it to burn right etc.
This issue was passed to me when I started.As I said I tried all the usual tuning etc as I have always done. No avail.
Anyway as it turns when I started from scratch again pulled the assembly from under the coil and jammed my head in there far enough to look up inside to inspect the coil for sooting I found extremely heavy soot and the problem.When the mechanic had installed the new coil and insulation the flat insulation that lays in on the floor of the boiler box prior to lowering in your coil was 1/2 over the hole where your electrode and fuel assembly go up through.When the fan kicked in it would flap it up enough to burn what appeared OK but would saturate the insulation.When the burner would cycle to off hence the afterburn.
Once the nasty job of desooting/washing out the coil and trimming the hard to get at insulation was done I reinstalled the burner assembly and it is 100% clean and pure.
Moral of the story is just because somebody put it together with new stuff I assumed they new what they were doing.Big mistake on my part! [lm]

A different truck they had blew a large gaping hole in the coil ( new 2007 Vac/steamer, hydraulic driven 5000 psi Cat pump,$380,000.00 purchase price for this truck) The manufacterer they bought it from demoed it for them when they bought it and showed them how to run it at 4500 psi to impress them.They therefore liked running it HIGH pressure without an unloader in the system.Just a 5000 psi pop relief.So 2 months go by and Kerplooee big hole in $4000 coil. [puke]
I Installed the new coil my second day there ,and sent the other out for repair, revamped their 25 GPM system with unloader and safety relief adjusted to 3500 psi.
The truck manufacterer had misled them grossly as the coil is rated for 3000 psi as are all the hoses on the unit.Safety factors are above this and that is what they were relying on.Looked good on the demo but not in the real world a few months later when it failed and causes them to produce $30-40,000 in revenue to pay for the repairs.
Moral of that story is just cause you pay big money don't assume they aren't going to try to fudge a little.
At least nobody got hurt!
PS thanks for the feedback!