Oil fired Furnace maintenance

Hello,
I am in Canada and have an oil fired furnace I use in my back yard to heat my "play shop' where I woodwork ...fix cars...etc.. I have this furnace on a switch so when I am done woodworking or whatever I simply shut it off when I am not using it. The problem is that on a weekend when I decide I have time to go back to the shop to play...I walk into the shop and throw on the furnace (room temp about -10 Degrees Celcius)and the furnace dosen't light right away but still pumps fuel into the combustion chamber....when it does light some 15 or so seconds later, it is trying to burn all the deisel oil from not lighting up right away which freaks me out...IE:.....big roar...black smoke etc... then it settles down and works fine... I think it's something inside that needs cleaning.............. perhaps the contact points that make the spark to ignite the fuel? Would there be a website where I can see a "hands on" cleaning of one of these things?....I did a Google search and came up with nothing....Thanks in Advance...Jim
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Jim & Lil" <jim.morris-at-sk.sympatico.ca> wrote in

First..I know what you mean. I live about 10 miles from Quebec and 70 miles from Montreal so I know what cold is all about up here. First of all, it's possible that the oil you're burning is getting too thick to atomize at the nozzle. When it's cold out, the spray coming from the cold metal of the oil burner just can't break down well enough to light off. In essence, all an oil burner does is try to break the oil down into something like a liquid "gas" that'll burn better. If this doesn't happen the oil burns in "globs" and burns dirty like you mention. I run a huge boiler room here in NY state and we have 7 boilers (the biggest is 600HP and the smallest is 250HP) and our tanks are outside. We have to have electric heat trace tapes on the lines to keep the oil flowing. One other thing you might try is taking the burner assembly out of the burner and doing a good cleaning. Replace the nozzle too. They're only good for about 1 year or so in regular use but if your oil is thicker than normal, it could wear it down sooner. Yes...oil can wear out a nozzle just as they use water to cut metal. Check your electrodes to be sure they aren't burned too far back. If they are, you might be getting post ignition. This is caused by the chamber filling with oil mist and lighting only after there's enough of it in there to finally hit the spark that the electrodes make. They should be about 1/8" apart, 1/16" past the front tip of the nozzle and about 7/16" above the center hole of the nozzle that the oil sprays from. Start there. It might take a little tweaking to get them just right depending on the spray angle of the nozzle. As a rule, the narrower the nozzle angle, the further ahead you put the electrodes. Normally the setting above will give good ignition for nozzles around the 70 to 90 angle. Try all the above and repost if this doesn't do it for you. I'll watch for you.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thank you 'Myname"...I printed out your posting and am going to do what you say. I had a furnace guy come by here two yrs ago and replaced the nozzle and a photo-electric eye he and charged me like 500 dollars for the visit and cleaning (200 dollars more than the cost of buying it used). The furnace probably has been turned on a total of 1 month total days at the most in running since his visit(shut off most of the time) so it may be fuel gelling perhaps?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.