Oil-Furnace Repair and Troubleshooting

When your oil furnaces quits, try some home diagnoses before calling in a professional, including these five tips and symptoms.

| January/February 1986


It's fairly simple to diagnose and repair residential furnaces, but precautions are necessary.


On the whole, oil furnaces are considered to be among the most durable household appliances. Even though many manufacturers claim that their units have only a 10-year usable life, a homeowner can often expect 15 to 20 years of service from a properly maintained furnace.

However, this is not to imply that an oil burner won't develop a few ailments now and then, typically on the coldest night of the winter. In some instances, only a minor repair or adjustment will be required, but in many cases, you'll need the services of a qualified heating professional to restore the furnace to good health. Even so, if you're familiar with the common problems that oil burners develop and their recommended repairs, you'll be better able to judge the quality of a repairperson's work and ward off the incompetent or unscrupulous.

In the discussion that follows, former EcoVillage Director Leroy Richter, who teaches a popular introductory course on furnace repair at a local technical institute, lists some common oil furnace problems and some ways to correctly diagnose the trouble.

1. The Furnace Won't Start 

First of all, Richter advises, press the reset button, which manually starts the furnace. It's located either on the primary control at the stack (on older models) or on the burner motor (on newer appliances). Push the button once or twice; however, if the furnace doesn't come on and stay on within 60 seconds, stop pushing the button and check the fuses or circuit breaker. Don't keep pushing the reset button, which merely loads more fuel into the combustion chamber. If you do and the furnace finally does fire, you'll have a "heck of a lot of oil" in there, Richter points out.

Sometimes the motor on the burner assembly will burn out, Richter says. If this is the case, the motor will have to be replaced. Over-oiling the motor, which is sealed, is probably the most common cause of failure. Another possibility, though a rare one, is a faulty starting switch on the motor, which is an inexpensive repair.

2. The Burner's Running, But There's No Fire 

In this case, turn your attention first to the burner nozzle. "The opening in a nozzle is smaller than the tip of a needle," Richter points out, "and the slightest amount of water or trash can clog it up." If it's been a while since you changed the nozzle, replace this inexpensive part and see if the furnace will now operate properly.

8/31/2017 1:15:42 PM

I found Mr Richter's article interesting but it did not answer my problem with my fuel furnace. He didn't address a problem of: Furnace starts and runs fine but there is now a smell of fuel oil in the air. Please help! Kate

samuel yo
2/4/2014 5:19:44 AM

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1/23/2014 10:35:22 AM

My oil furnace vents out the side of my house about 8 inches off the ground. When we have snow storms/blizzards here in Nova Scotia the vent gets covered in snow and of course my furnace stops. I am disabled and it is very difficult to try keeping up with clearing the snow & restarting the furnace. Can an extension be added to have the vent higher off the ground and if so who would be able to do it?

1/3/2014 7:58:49 AM

When I got up this morning, my furnace was running but no fire. About an hour later, I could tell the house was getting warmer, so I checked and the flame was working. What would cause this and should I be concerned that something isn't right? The forecast for this week-end is -15 below.

12/25/2013 10:17:13 AM

oil burner runs but no heat...becket oil burner not firing up

12/21/2013 4:51:11 AM

I have an old oil fired ceentral heating system and having a problem with the oil pump , its a Danfoss MSLA 032 . can this be replaced with a suitable altenative , if so ,what ?

12/15/2013 5:05:34 PM

Does anyone know how to have two systems share one heating oil tank? Do I just get a t splitter on the send and receive?

11/20/2013 11:49:39 AM

I have a forced hot air system and the control box reset button keeps having to be hit. What are the possible causes for this? How do you see replys in this forum?

11/14/2013 7:52:45 PM

Had no heat, found this site. Got the book that fixed my system.Got the heat running again. Thanks! Gene http://homeoilheatingsystems.com

11/9/2013 10:15:12 AM

How do I get to see the answers to comments

11/9/2013 8:21:08 AM

Hi My beckett oil burner nozzle keeps blocking. changed the nozzle and filter run good for 4 to 5 weeks. is there a good additive that will stop th slug ahd water. oil tank and oil burner is 9 years old and the tank is in the basement.

8/22/2013 2:16:26 PM

I need to hire someone to do http://www.needaplumbercanada.ca/en/furnaces_in_edmonton.html. Fortunately mine isn't oil, though I'm not sure what type it is.

1/21/2013 3:12:59 PM

Hi, I have an older Wayne oil furnace in my mobile home and when the blower comes on it run great for 8-10 minutes then makes a loud rumbling/banging sound. I recently changed the nozzle, cleaned the filter, and cleaned the chimney and no change. Please help, cold and frustrated!

12/7/2012 3:27:29 AM

Hi, My oil heater burner is always stop by itselt{the oil tank is full),every time when push the reset butten,the burner can fire until the tempeture that I set but after the tempreture is going down below the point the burn is still not work just occasionaly Why? Thanks

cory thompson
11/16/2012 3:01:08 PM

my fuel oil furnace just got filled and it turns on and works fine for a few minutes and then shuts off, any ideas?

10/24/2012 12:42:34 AM

Beckett oil burner changed nozzle flame senser cleaned eleectrodes burner fires after pressing reset button . But shuts off after a couple of minutes. What could the problem be ?

tony paulin
1/29/2012 9:48:26 AM

hmm links not working? I mean this: http://www.oilfurnacerepair.net/

tony paulin
1/29/2012 9:47:38 AM

Thanks! Together with this "how to" about oil furnace repair I got my Oil Furnace working again! I'm so excited!!!

johnny gallen
12/13/2011 12:01:25 AM

i have a oil furnace the burner comes on and cuts off reset it fires back up till time cut off then i have to do it again does not do it all the time it just started ,are they a nozzel be hide the fuel line i can clean or replace

alicia hibbler
12/12/2011 12:31:37 PM

i changed the nozzle and the filter but my furnace still wont work what do i do now

jim ries
12/4/2011 4:20:41 PM

http://homeoilheatingsystems.com/Oil/ for troubleshooting problem

1/23/2011 8:21:04 AM

we changed the nozzle 2 times in the last 2 weeks and last time had the guy put in an inline fuel filter now its not working again. any suggestions

mark _2
2/22/2010 8:41:25 PM


2/14/2010 5:59:37 PM

Is there an additive that will suspend the sluge in the bottom of the #2 Fuel oil tank, that will allow the fuel to be burned with the suspended sludge?

2/4/2010 4:45:47 PM

I have an oil burner with forced hot water using base boards. Just recently I have had problems with air in the lines that makes it sound like water gurgling in them. Can you please tell me how to get rid of this problem. Can the home owner do this?

david _1
1/19/2010 11:58:44 PM

i have an up flow oil furnace, when i turn up thermostst to " turn on " the furnace i notice that furnace comes on but cold air only come's throgh vents, when i go downstairs and hit the reset button on the thermostat the furnace kicks in and starts to heat up !, after a few moments the reset button pops up and shutsdown the heater , i believe it is the "filter somewhere in the supply lines to the motor on furnace that the repairman last year showed me that was the cause of my same issue !!, he showed me how it was completely clogged with thick oil sludge , he say's caused by " dirty oil tank , that he say's should be professionally cleaned or get a new tank !, my ? to you is where is this filter located and are there more than 1?, d i need special tools?, i think not , but i have never worked on a furnace before , my tank is located same floor , approx 8 ft. from furnace , 2 qty copper pipe come up from tank over to the oil filter and then through oil filter and connects at 2 points to i guess the motor / heater , i am guessing it's located somewhere between the tank and the motor/heater attached to furnace , please help explain if yu can walk me through , i don't want to get stuck with a $100.00 bill or more , for just this filter !, thank you, desparate in tacoma , david .

1/3/2010 9:08:29 PM

I have an oil furnace (Boiler) This thing is sooo fusterating I had it cleaned i have new filter nolese primery were red button is 1 y old 1 y old transformer new oil tank newlines every thing done what it suppose to this furnace will work fine for 7 days shut of work for 7 days shut of works grate in between shut of i dumped sulution to see if that would help shut off again fires up right run right heat water right I am stumped furance man stumpied it was ajusted several times any new ideas

4/10/2009 9:30:21 AM

My oil burner fuel pump runs for 10-15 seconds and drops out. I know the tank is full but it acts as if the pump has lost prime. Service guy says pump has no suction and is too old to repair. I think they want to sell me a new system. Question: are fuel oil burner pumps repairable/replaceable?

2/14/2009 10:44:57 PM

I have a oil burning furnace and it stays on for around 15 seconds then shuts of and this happends every half hour there is fire but dont stay on long enough to warm up my house any idea why it wont stay on long.

m c_2
2/14/2009 7:40:17 PM

Furnace issues

1/28/2009 2:13:38 AM

1/3/2009 3:24:40 PM I have a oil burning furnace,and when it hasnt run in awhile its like it forgets what to do. I turn it on, it stays on for about thiry seconds and then it shuts off. I press the restart button and it starts right up, but only for thiry seconds and it does this repeatily. If I stant by the furnace for about 5 mins restarting it, then it runs find for hours. 1/28/09 I have the same problem. Any suggestions?

1/22/2009 10:10:42 PM

Can Anyone explain what might be wrong? The oil furnace came on and all was well but the room temperature went up to 95. The programable thermostat did not show a time or temp so the furnace was turned off at the thermostat and it stopped and cooled off. WEho should I call for service? I would appreciate and feedback. Thanks, Harriet

tom arnold
1/6/2009 7:39:11 AM

Greetings I checked all the thermostats in the home. I turned off the boiler switch for 30min and then turned it back on to reset the boiler. I also depressed the reset button 30min after attempt #1. there is no call for heat. The oil burner runs for 10seconds and then shuts down. It then fires up again after 60seconds and fires once again. Issue is not hot water as no one showered during that interval where any amount of hot water would be required. Please help...this is insane. Thanks Tom

1/3/2009 3:24:40 PM

I have a oil burning furnace,and when it hasnt run in awhile its like it forgets what to do. I turn it on, it stays on for about thiry seconds and then it shuts off. I press the restart button and it starts right up, but only for thiry seconds and it does this repeatily. If I stant by the furnace for about 5 mins restarting it, then it runs find for hours. We have had the nozzle, filter and eye sensor changed.

1/1/2009 10:29:53 AM

push reset, furnace runs 30 seconds, shuts off, reset, same thing keeps happening. Same as Ronald 12/27/08. Thank you.

12/27/2008 5:01:05 PM

I have a oil burning furnace,and when I turn it on, it stays on for about thiry seconds and then it shuts off. I press the restart button and it starts right up, but only for thiry seconds and it does this repeatily. Can you help?

12/4/2008 1:59:38 PM

ive got a beckit forced hot air oil furnace and ive change to oil tip on the tourch and air filter but now im hearing a small sometimes a biger boom like a fire cracker sound when it starts up a small flame comes out of that hole with the metal latch in front of the furnace and i smell an oil smell in the house. someone told me its an air flow problem please someone has probly had this problem before. how do i fix

12/2/2008 10:58:31 AM

Hello, I wanted to know what would cause my oil furnace to rumble and smoke at the same time? The smoke is coming from my dampner. PLEASE help.

11/27/2008 12:22:14 PM

My oil furnace runs for days at times some times i hav eto hit the reset buttion to start it back up. and sometimes it seems that i get to much presser were it gos to the cimney then when that happens i rais up the squar box that sends the juice to the egniter's then it will work good for a little while and it keeps doing that.... can any one help please???????? please email me at eatarr0ws91@aol.com if you can help thx

11/22/2008 8:23:11 PM

I changed the oil filter and nozzle for my old Oil Furnace (with forced heating air). It's working but fuel oil smell is coming in the house. I turn the termostat off at night because I'm afraid of geting sick or worst, (poisoning). Can you tell me what it's causing it and how I can fix. Your help is much appriciated. Thank you,

11/20/2008 8:01:31 PM

ho do i bleed my oil furnace,before starting it for the winter ?

jim ries
11/20/2008 12:23:34 PM


yvonne _1
11/17/2008 6:55:09 PM

My furnace will fire, shoots oil, then quits?? what can i do ?

11/2/2008 11:48:54 PM

I have an old furnace that is spewing out steam from the top and near the sight glass. This unit does not supply hot water, just heat. Should I drain all the water out an then add water and start it or is there a bigger problem? thanks.

joan wesley
10/30/2008 9:46:25 AM

Raw oil smell when FAO furnace kicks in...particularly noticeable first thing in the morning. Is this dangerous to our health? Do you have a solution?? Joan

bridget faria
10/23/2008 10:11:13 AM

My furnace was just "cleaned" yesterday. When I came home and kicked on the heat my fire detectors went off and I found black soot covering everything. Can someone please tell me what may be the cause? This cant be normal. Help please and thank you,

10/7/2008 7:53:52 AM

Hi! My oil burner keeps shutting down - I have to go down stairs and push the reset button and then she fires up for a few minutes and shuts down again. The burner keeps buzzing - goes away when I push the reset button and the burner starts up. I've had numerous persons look at it - changed the batteries on the thermostrat ....... OK - out of ideas. Any suggestions? Tired of running up and down the stairs.

9/21/2008 2:28:30 PM

Ron, Hitting reset switch issue may be the blower motor has a dead spot, or opens up when heated... after cool down it starts because windings close up. I had this problem pnce, replaced blower motor and solved it.

8/21/2008 2:54:52 PM

The stack temperature is very high on the unit. Could you list some causes for this, and could one be the heat exchanger needs cleaned?

bob pasa_1
8/15/2008 3:27:44 PM

my york oil furnace will not fire up after primary is pushed,the blower will then start running.Is the primary contol fried?

1/21/2008 9:26:23 AM

Hello, I too have been experiencing the same problem as Terry who has sent an e-mail to you on January 2, 2008. Forced air heating system with a oil fired hot water tank. I have cleaned nozzle in the motor as well as changed the air filters. But still the problem continues. I can go one possibly even six days without hitting the reset button. There has been times that the reset button has to be hit a few times throughout the day, however this is rare. Could you please help. Thank you

1/19/2008 10:02:23 PM

Where is the burner nozzle located on an Oil Burner?

1/16/2008 8:29:48 AM

was having to keep hitting the reset button to get my furnace running, sometimes it would take a dozen times before it would start. When it did I could smell the fuel oil through the house. A repair man came out & worked on it and now the burner runs but when the temperature gets to what I have the thermostat set at the burner shuts off but the blower keeps running continously. Any ideas? Thanks much for your help

1/6/2008 9:12:19 AM

When our fuel oil furance kicks on, we get a terrible oil smell. We have replaaced the filters but that doesnt seem to help. What can we do on our own now before having to spend a ton of money on a repairman?

1/5/2008 7:32:58 AM

Hi, I've seen my problem listed several times - is there someone here to answer? My furnace runs once and shuts off. The reset button has to be pushed and then it will start again although for a shorter burst every time. My it's cold.

1/3/2008 11:09:26 PM

My stack mount relay went bad. Had it replaced and had the oil heater serviced, filters, nozzle, electodes cleaned, and so-forth. Now the heater will run a few cycles and the stack relay will trip and have to be reset. If I catch it before it trips and bang on the motor (motor is buzzing) it will fire up. Does this mean the motor is going bad? Thank you.

1/2/2008 1:22:28 PM

Have an older model Atlas Webster oil furnace and have replaced the burner tip and the ignition transformer. When it fires it starts with a small bang and a puff of smoke comes out the small door in front. I need to know what the oil pressure should be and what the gap between the electrodes should be as well as how far the electrodes should be located in front of the nozzle. I would greatly appreciate assistance with this. Thank you.

1/2/2008 7:31:49 AM

I rent a house with an oil furnace, it's a big house and a little old but in good condition so I expect it to be just a little pricey to heat but every time I put the same amount of oil it runs out faster and faster for example $300 DID last me 1 month, then 3 weeks, then 2 weeks, now i got oil 10 days ago it's nearly empty!!! I was told by 2 different family members who looked at it and bled it for me that the furnace is taking in a lot of air (and spilling water i think) and was wasting at least 25% of my money-at that time, the furnace is old and I don't own it so I can't replace it, however, the situation is getting worse and worse I don't know whats wrong, do i need and oil burner specialist to check if its burning properly? I need some kind of repair just not sure what I need or who to call...

1/2/2008 2:06:50 AM

my oil furnace might run for days then suddenly quit..if i push the reset it fires & runs fine it might run 1,2,3 days before failing to ignite again but if i hit the reset 1 time its fine again...no bleeding required...any ideas what might be causing this?...thx

1/1/2008 11:20:13 AM

To get my mother's furnace to run I have to keep hitting the reset button three or four times. There seems to be a lot of air coming into the deairator. Each time the reset button is hit the air decreases until the furnace will run. Is there a oneway valve that keeps the fuel from draining back into the tank once the pump stops after the house has reached temp. Our repairman says the fuel line is obstructed and needs to be replaced. He did a test( I am not sure if it was a pressure or a vacuum test.) and said it read 9. He blew the line out andi it dropped to 5 but the furnace still will not run right and the air seems to be worse. Is he right and is there a back flow valve?

12/29/2007 12:29:38 PM

We just put 100 gallons in our tank a few days ago and our furnace has all of a sudden just quit working...everytime it does this I reset the button and it starts again. But we will wake up at 5 inthe morning and it did not register the temp and it never turns on again. help!

12/26/2007 10:44:27 PM


12/25/2007 7:01:35 AM

I came back from vac. and my oil ran out. I got oil, I need to bleed the burner and get it ignited. (Beckett Burner).

12/22/2007 11:02:54 AM

When my oil burner is running we hear a high-pitched whining noise upstairs. Not next to the burner. I've been told that it is the fuel feed line vibrating. I this so and if so how can it be fixed. Thank you. Darwin Davidson

12/18/2007 11:34:16 AM

my furnace will come on and stay on for about 5 min, and then cut-off and then it won't come on again until I push the reset button. Then it does the same thing again.

12/18/2007 7:49:25 AM

I have to keep bleeding ail out of the oil supply line, why?

12/17/2007 2:08:25 PM

I believe the pump is not working tring to find new one its a old furnace but it runs clean please me know if you help

12/16/2007 5:38:05 PM

My mother-in-law just called and said that she's run out of oil for her furnace. A neighbor said she should use kerosene until the oil is delivered. Is this safe?

12/14/2007 5:31:47 PM

My oil furnace also runs for a couple cycles. I replacedthe following... Fuel tank, filter ,opened pump and cleaned thuroughly, new igniters gaped,speced to specs, new nozel, thuroughly blew out lines with air,[before filter etc.]The other night it ran FINE!! Now it's old self, Two cycles.Please Help!!Cooper Landing, Alaska

12/14/2007 10:02:35 AM

fuel oil furnance runs fine except it burning louder than before?

12/13/2007 10:53:13 PM

My oil furnace will run one cycle then stop. As soon as the first cycle is finished, the breaker kicks out and must be reset before the furnace will cycle again. The first time this happened, the furnace ran for two days, then one day, now one cycle or two. HELP!

12/10/2007 5:48:01 PM

Hi I am having some trouble with my oil I got to bleed the air out of the line to get it to light it will run for 2 mins then it will get air in the line. I took the fittings apart and retighted them all back up I can get it to run out of a bucket but it will not run from my tank that is under ground do you think my pump is getting bad.

12/9/2007 4:23:25 PM

my oil furnice want start i ran out of oil ive put some in t bled it it started then but after i got done bleding it it dosent want to start again what do i do

12/6/2007 3:34:43 PM

I have soot coming through my registers into my house. I have an oil burning furnace. Is this a health hazard? Should I be concerned?

12/4/2007 11:44:14 AM

I had a new furnace installed May 2007, After many hours of running time the furnace is still amitting a very strong oil smell in the house.The repair man said there is nothing wrong with this furnace ( Intertherm ) The biggest problem we find is that you never know when the smell is going to start.Sometimes it is half way through the cycle, other time it could be at the end of the cycle.But the smell is very strong, could you please help me with this problem, thank you Rob.

12/1/2007 4:39:42 PM

We are having a problem with a fuel oil furnace in an older mobile home. We replaced the nozzle, the filter, the fire sensor, and a few other things. We checked the coil and seemed to have good fire there. We checked the ignitors for continuity and it seemed to be okay. Everything seems to be working correctly, but the furnace wont ignite. If you can give us any advice, we would appreciate it. Thank you.

11/30/2007 8:38:32 AM

My oil furnaces keeps going out. I have relaced the nozzle several times because they arw wet Please tell me what else I can do.

11/30/2007 8:35:47 AM

My oil furnace keeps going out.The nozzles are wet and I have relaced them several times. Please tell me what to do.

11/27/2007 6:23:13 PM

I have an oil burner that feeds 2 floors in my house. The upstair floor pipes get really hot while the downstair floor pipes range from cold to warm. What could be causing it. I have looked at the pipes but see no drain to drain out air in pipes

11/25/2007 1:54:01 AM

My oil burner will come on then go off 15 mins later the burner goes on then off with in 5 mins the fan will come on and heat my house. I need your help?

11/25/2007 1:44:44 AM

My oil burner will come on then go off, about 15 mins later the burner goes on then goes off. With in 5 mins the fan will come on and heat my house. I need a diagnose with this problem ? Thank You

11/23/2007 8:22:17 PM

My furnace typically stops working when the oil level gets to about 59 gal. Is this a built-in warning feature and if so can I override it?

11/19/2007 1:38:54 PM

I started the season with a new nozzle and air filter. The furnace will run once or twice, then I have to clean the outside of the nozzle in order to get it running again. I changed the nozzle multiple times and ran can after can of oil out of the line in order to make sure that it is clean. Why is the outside of the nozzle getting dirty?

11/18/2007 6:55:31 PM

I have to bleed the air out of my line or my furnace will not heat.

11/17/2007 7:23:05 PM

i have to keep bleeding my furnace everytime i want it to heat i am getting air in my line why?

10/10/2007 6:45:38 PM

my oil furnace won't fire up i installed a new ignition transformer,new nozzle,filter and electrode points. doesn,t seem like there is any spark. furnace isn,t lighting.please send some solutions. thanks

9/12/2007 1:25:54 PM

oil heat repair and troubleshooting guide www.on-linegraphicsinc.com

4/27/2007 10:03:16 PM

I ran out of oil now when I fill up my tank do I have to re-light the furnace and hot water tank or do i just push the reset buttons If I have to re-light How do I do that

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