blue smoke

[commanche]

the repairman thought the igniter might be getting bad.some said it could be a after drip?what is after drip and how is it corrected??when i looked in the firebox are running about 3 minutes, i could see like a white smoke going up.is that normal?i also dont see that blue smoke coming out the chimney all the time on start up only a couple of times usually at first start up in morning after waking up ,i turn it from 72 to 74 to warm the house up and then the smoke comes out.

[what96]

is this oil? Must be if there is after drip mentioned. is th oil tank at or above the level of the furnace. Oil quality comes to mind. Once I worked on oil boiler that was filled with about half gasoline instead of fuel oil that one burned whitish/blue but also wouldnt rise water temp in boiler fuel oil has about 140000 btu per gallon gsa has only about 65000. How is it heating. Is the oil filter clean? Has the nozzel been changed? sometime a check valve inside the oil pump fails causes nozzel to drip on off times.

[jdenyer]

Are you sure it's not water vapor condensing when it hits the cold air outside the chimney? Morning light can give this normally white vapor a bluish hue. Just a thought

[Al Gregory]

Is it a steam boiler? or forced hot water? What is the brand name?

[commanche]

-it is hot air oil furnace 30 yrs old.i opened the door on front to watch flame and there is smoke going up,white looking.when i go outside to look at chimney ,SOMETIMES at start up blue smoke like car burning oil comes out for about 5 seconds,then white vapor then it disappears.my question is that puff of blue smoke at first.some say after drip, some say igniter going bad,some say igniter out of adjustment,some say air out of adjustment..any clue ,why the blue??there is no smell of oil coming from the vents in the home..

[1manband]

Not to be a smart ass or anything but, 30 years old? You are fortunate anything is coming out of the chimney, blue or white.

[commanche]

i thought that too but i talked too many repairman ans some said they removed furnaces 50 yrs old and still good.they could have sold me a furnace and said,oh its 30 yrs old.many said thats a lot of sales tactics and furnaces can go m,ore than 30 yrs.i was ready to buy a new one too but they checked it and said its OK. i was surprised but there are honest people out there.test showed 80%eff on burn and no smoke on the paper.also we smell no fumes in the house thru the vents.chevy garage has a hot air furnace that is 40 yrs old and they said it is OK.

[commanche]

that blue smoke only comes if furnace is turned down over night and you turn it up in morning.i watched it today when she turned it up first thing inmorning.blue smoke came out for 5 seconds ,then white which i think is hot air hitting the cold air,20 degrees out side,then it gets real clear and you can see the heatwaving in the air above the chimney that is clear.so, it must be getting oil at start up or something is not firing quick on start up.i think its oil laying in firebox overnight then when the thermostat is turned up in morning, puff, out comes that unburned oil.question is,WHAT IS CAUSING THIS,IGNITER,AFTER DRIP, AIR OUTOF ADJ,PUMP ETC. the nozzle was changed, filter, test of smoke done.i dont think its the oil because smoke would come out blue all the time,its ONLY at startup in morning..that acts like UNBURNED OIL but i am no expert on this.any help will be appreciated, thanks

[hvac-tech-lane]

Your furnace must have been retrofitted with a flame retention burner for 80% eff. it would not be the ignitor as this would cause poor starting i.e. rumble, puffing, odor, soot, Probably drip from a bad pump cut off, your serviceman can check this with a pressure gauge connected to the nozzel line should hold 80% of run pressure after shut off.
P.S. 30 years old, no problem 80% eff. just as good as a new unit and no crack in the heat exchanger, stay with it.

[Edited by hvac-tech-lane on 02-19-2005 at 11:52 AM]

[hvac-tech-lane]

Originally posted by 1manband
Not to be a smart ass or anything but, 30 years old? You are fortunate anything is coming out of the chimney, blue or white.

1 man, what criteria do you use to determine when you recomend a piece of equiptment be replaced, how old are you.