Oil burner won't start or won't keep running:

Step by step checklist to diagnose & repair an oil burner that won't run or keeps stopping.

Oil burners used on oil-fired heating boilers, furnaces, or water heaters can often be diagnosed using a visual inspection approach as well as (optional) simple test equipment described here.

This article series answers most questions about all types of heating system troubleshooting, inspection, diagnosis, and repairs. We describe how to inspect, troubleshoot and repair heating and air conditioning systems to inform home owners, buyers, and home inspectors and students of heating service methods about common heating system defects.

The articles at this website describe how to recognize common oil-fired heating appliance operating or safety defects, and how to save money on home heating costs

Oil Burner Won't Run: Diagnostic Steps - what to check in what order

This article series explains the inspection, diagnosis, & repair of oil burners used in heating appliances such as hot water boilers, steam boilers, & water heaters.

If your heat is not working properly, and the problem does not seem to be the oil burner itself,

see NO HEAT - BOILER - hot water or steam heat

or
see NO HEAT - FURNACE - forced warm air heat

We have collected oil burner diagnostic procedures from several texts, [1] - [22] adapted, expanded, and generally re-ordered steps in order of most likely to be successful and easiest to perform.

For example it makes sense to check for a valve or switch that is off, or an oil filter that is clogged, before we start disassembling the fuel unit.

If the OIL BURNER WILL NOT START

A good starting point is

at HEAT WON'T TURN ON. You can return here from that article. Start right at the room thermostat.

Or jump right into the detailed oil burner diagnostic step sequence below.

Step 1: Make These Quick Visual Checks 

• Power switched off to the unit
  
  - ELECTRICAL POWER SWITCH FOR HEAT
• A fuse or circuit breaker or fusible switch has blown
• Adequate oil supply in the oil tank
  
  - OIL TANK GAUGES
• The oil supply valves are all open
  
  - OIL LINE QUICK STOP VALVES
  
  and
  
  - OIL SUPPLY LINE SAFETY VALVES, OSVs
• The thermostat is really calling for heat - it is switched to "heat" and proper time of day
• The room temperature is below the thermostat set temperature
  
  - THERMOSTATS, HEATING / COOLING
• Evidence of an oil-flooded combustion chamber (you do not want to try turning on the burner in this condition as there is danger of a horrible puffback mess)

Step 2: Oil Burner Electrical Power Tests

First: test for voltage across terminals 1 & 2 at the stack relay or cad cell relay primary control

If there is no Voltage at the Oil Burner

• Check the LIMIT SWITCH, BOILER,
  
  check
  the RESET SWITCH, HEATER PRIMARY CONTROL,
  
  Check
  the LOW WATER CUTOFF VALVE (if it's hot water heat or steam heat),
  
  check any fusible switches,
  find and check all of the electrical switches that can turn off the unit (the stair switch, the service switch, the breaker or fuse in the panel
  
  - ELECTRICAL POWER SWITCH FOR HEAT.
• AMPS MEASUREMENT AUTOMOTIVE DC
• AMPS MEASUREMENT METHODS
• DMM DIGITAL MULTIMETER HOW TO USE
• VOLTS / AMPS MEASUREMENT EQUIP
• VOLTS MEASUREMENT METHODS

If Voltage is Present at the Oil Burner

Continue oil burner troubleshooting with Step 3 below

Step 3: Thermostat Tests

Jump across the thermostat terminals. At the primary control remove the existing thermostat wires and connect a jumpe wire across the two T T terminals.

If the oil burner starts continue at step 3a below.

To diagnose heating thermostat problems

see THERMOSTAT DIAGNOSTIC GUIDE 

 

Step 4: Oil Burner Start & Run Diagnostic Steps

If the oil burner relay pulls in and

The oil burner starts, continue at Step 4a below.

 

Step 4a: The Oil Burner Starts & Runs

• Check the flame for normal appearance,
  
  The system seemed to run OK when you jumped the TT terminals, right?
  
  If the flame is normal (not smoky or loud rumbling or intermittent) reconnect the thermostat as we describe just below.
  
  If the oil burner flame is not normal,
  
  
• Re-connect the thermostat
  
  Remove your thermostat jumper, wirere-connect the normal thermostat wires to the T T terminals, and make sure the thermostat calls for heat.
  
  

  If the burner runs OK & does not again go off on reset or "lock out" then continue with the steps just below at 4a.
  
  If the oil burner will not start and run then continue with the steps below at 4b - Oil Burner Still Does Not Start

Step 4a-1: Oil Burner Runs, Not short cycling

- the system should be OK

Step 4a-2: Oil Burner Runs but Short Cycles On/Off

Is the oil burner short cycling on-/off every couple of minutes or less?

This condition can lead to the oil burner going off on safety-reset.

Your service tech will probably check the following:

• Check for loose wires at controls, power, thermostats &c.
• Check for hot or burned relay switch contacts,
• Check for thermostat bounce or thermostat internal wiring or flat cable connection defects
  
  - THERMOSTATS, HEATING / COOLING
• Check the aquastat HI, LO and DIFF settings
  
  - AQUASTAT CONTROLS
• Check also for improper voltage.
• Check the low water cutoff switch (that can also bounce) if one is present
  
  - LOW WATER CUTOFF VALVE
• Check for improperly-set heat anticipator
  
  - HEAT ANTICIPATOR Adjustment (if present) or
• Check for improperly set HVAC cycle or swing temperature variation
  
  - THERMOSTAT SWITCHES, INTERNAL
  
  If all of these look ok, you may need to change the primary control relay.
  
  Thanks to HVAC tech Anthony Alaggio for suggestions about oil burner short cycling.

  Example: of oil burner short cycling: (Jan 2, 2018) Deb said:
  
  We have an older weil mclain gold high efficiency heater. Recently, it has started to go on for fifteen to twenty seconds, stop and then restart for another fifteen to twenty seconds and so on.
  
  Every time it does this, we hear a clicking sound when it goes on and another when it goes off.
  
  Our cast iron water radiators only get lukewarm to the touch even though the thermostat is turned up 5 degrees over the room temperature. We have a call out to our plumber but we were wondering if our system is safe to run.
  
  (Jan 2, 2018) (mod) said:
  
  Deb The system needs service promptly. Turn it off. SHORT CYCLING oil burners can end in loss of all heat or
  
  also OIL BURNER SOOT & PUFFBACKS
  

Step 4a-3: Oil Burner fires but just intermittently - oil burner chatters or starts and stops

• Check for loose electrical connections at all power and control wiring connections.
  
  Here is an example from reader M.F.

  ... the furnace draft fan began to pulse several times upon starting. After making sure the control module showed a steady green, I asked a friend and he suggested that I wiggle all the spade connectors to be sure there is good contact between the copper and aluminum.
  
  It seems that there only needs to be a little corrosion to cause problems. That seems to have done the trick. - M.F. 12/24/2014

 

Step 4b - Oil Burner Still Does Not Start or Starts then Shuts Down

Step 4b-1: If the burner oil burner does not fire up at all

there may be a problem with the thermostat or the 24V thermostat circuit. You may need to change the 24V transformer or the thermostat.

If the oil burner motor runs, continue below with Step 4b.

If the oil burner motor never even starts to run, contue at Step 4c below.

Step 4b-2: If the oil burner fires up but goes off on reset again

• Check for a bad flame, bad firing, dirty nozzle, electrodes, oil leak at the nozzle adapter, blocked combustion air
• If a stack relay is used, check for a dirty or broken helix
• If a cad cell relay is used, check for a dirty or failed cad cell eye
• If these look OK you probably have to change the primary control relay

Step 4b-2.1: If the burner motor started but no flame: no oil flow

• No oil flow comes out of the burner. 
  
  You already checked that there is really oil in the tank, right?
  
  - OIL TANK GAUGES
• Check that the oil tank float gauge is not stuck.
• Check for a dirty or clogged oil filter
  
  - OIL FILTERS on HEATING EQUIPMENT
• Check for a dirty, clogged oil burner nozzle
  
  - OIL BURNER NOZZLES [PDF]
• Bleed the fuel unit of any trapped air, then check the pressure (pressure out, vacuum in) on the oil lines.
• Check any oil safety valves, check valves, PRVs,
  
  OIL SUPPLY LINE SAFETY VALVES, OSVs
• Check for a clogged strainer in the oil burner fuel unit
• Check that the burner motor is turning the burner blower and fuel unit (a bad coupling or a bad motor)
• Check for an oil line that is clogged or blocked by ice (outdoor tank) or sludge - a clue is to see how much crud is in the bottom of the oil filter canister.
  
  OIL LINE CLOGGING FIX
• If there is oil flowing freely at the oil line and all of the above check out, we suspect that the fuel unit is not pumping.

Step 4b-2.2: Oil Burner Started, Oil Delivered, No Ignition

No ignition: oil comes out of the nozzle but there is no ignition. Check

• Check for voltage 
  
  at the primary, terminals 2/4 or if constant ignition 2/3
• Test the ignition transformer 
  
  for spark (old timers know a screwdriver trick; if the flame is blue and reaches mostly across the gap of the transformer springs with the screwdriver an inch or so away, the transformer is probably ok.
  
  Watch out: this is very high voltage: you could be shocked or killed - this old-timer's trick is not officially recommended and our service tech declined to be photographed performing this step.
  
  Other, recommended oil burner ignition transformer test procedures are provided by the manufacturer.
  
  If the transformer is weak the spark will be dead, not bridge the gap to the screwdriver, or not extend to at least 3/4 the width between the contact springs, or will be orange not blue in color.
• If the transformer does not check out,
  
  replace it.
• If the transformer looks OK 
  
  check closely the ignition leads including for cracked shorting ceramic insulators in the burner assembly or an improper or improper gap or damaged electrodes.
  
  You already looked to be sure the electrodes were not bridged with soot and crud, right?

 

Step 4c: Oil Burner Motor Never Starts

Step 4c-1: If the burner motor does not start

• Check primary terminals 2 & 3
• Check for live voltage
  
  at wires powering the motor (if no power there and the relay pulled then there may be a broken wire)
• Check for thermal overload:
  
  If hot and ground are good at the motor, check for a thermal overload switch pop on the motor - if it's out, let the motor cool, reset it and start again.
  
  RESET SWITCH, ELECTRIC MOTOR
• Oil Burner Motor Tests
  
  If after reset of the thermal overload the motor still won't start, replace the motor.
  
  At ELECTRIC MOTOR DIAGNOSTIC GUIDE
  
  we describe both offline and online electric motor circuit analysis (MCA) test procedures.

Step 4c-2: If the relay does not pull in,

• If it's a stack relay, re-step the relay contacts inside the control.
  
  STACK RELAY SWITCH
• Check the lock switch
  
  - RESET SWITCH, HEATER PRIMARY CONTROL
• Check for cold relay points - broken, not connected
• Check for a broken or clogged helix in the stack relay
• Check for a bad cad cell relay

 

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2022-10-14 by InspectApedia-911 (mod) - oil burner didn't re-start on its own

@1WhoFlew147 ,

I understand completely. Incidentally even if someone had previously tried to bleed air from the system.

If they didn't know how to do it and didn't know all of the places from which to bleed air they could have left a problem behind. An example of a more subtle problem Left Behind is a loosened flare connection on the oil piping line that could be continuing to let air leak into the system.

On 2022-10-13 by 1WhoFlew147

Hi everybody, Going to do my best to keep this really brief, a quick synopsis.

After running out of oil 3-4 nights ago my oil burner didn't re-start on its own as it had before.

Enlisted my friends' husband to help. He tried unsuccessfully to fire her up, he then enlisted his wife's brother for help, he also had no luck.

I being frustrated pulled up Google and found the manual, figured out that we had to hold in the reset button count from 1 to 30 by thousandths sure enough she fired up.

Heat came on, house warmed up however after the temperature stabilized and the burner kicked off it's never reignited.

I did go down and try to restart it as I did before it didn't work I may have tried two or three times that night and subsequently tried maybe two more times but I'm reluctant to keep doing it, obviously I'm scared to screw anything up and or make things worse.

Failed to mention that after I went down & restarted it successfully, I left the 2 guys down there nursing their bruised egos lol (I'm kidding) the brother said he did bleed the air out of the line(s), now for how long he did that, p not sure, I left the area.

You should all know that I am a new homeowner due to my aunt passing away.

I've never had to deal w/ a issue like this, so please forgive my lack of knowledge. So I'm here sending out an SOS all ears, what are you guys think?

On 2022-08-06 by InspectApedia-911 (mod) - cast iron boiler malfunction

@Sansy,

Most common cause of oil burner malfunction after running out of oil is that air needs to be bled from the piping, filter, & fuel unit, and at this point the oil burner may need cleaning & nozzle replacement.

On 2022-08-05 by Sansy

Peerless cast iron boiler was out of oil for months now got oil but it starts then stop

On 2022-03-03 by Inspectapedia Com Moderator - motor won't start

@dendelvecc,

Please try stepping through the Diagnostics given on the page above and let me know if that works for you

On 2022-03-03 by dendelvecc@167

motor won't start

On 2022-02-01 by Inspectapedia Com Moderator

@Jim,

If oil burner were drawing sir in the fuel system I would expect there to be a bad flame and the burner to trip off on safety reset.

If the safety reset is not tripping it may be that you have a loose electrical connection.

On 2022-01-30 by Jim

Have a becket oil burner just had cleaned an serviced the problem never showed up. It ones on fine then goes on an off several times the. Runs normal. I have replaced the aqua stat before calling for service any clue. Could it be the pump sucking air thanks

On 2022-01-30 by Inspectapedia Com Moderator - primary control must be malfunctioning

@Anonymous,

With the apology that it's not possible to be confident in an oil burner diagnosis based on a little text exchange,

if the burner is trying to start - i.e. motor runs - then I don't suspect the primary control as the first defect.

If there is oil delivered but no flame I would look at

- a weak or failing ignition transformer

- improper electrode adjustment position or a cracked, shorting electrode

If the burner motor runs but no oil is delivered I'd look for a blocked nozzle, nozzle adapter, or a problem in the fuel unit itself

A more-orderly flow chart of diagnosing a non-starting oil burner is above on this page. Give that a look and let me know what you find as that'll help others.

On 2022-01-28 by Anonymous

@Inspectapedia Com Moderator,
I understand your concerns. I’m very familiar with this system as I am the installer and have maintained it all these years. The boiler is shutting down correctly. It just refused to start a few times. And there is no leak ( I’ve been there before also. Wasn’t pretty).

I had the co2 measured and it’s in the correct range. I’m thinking the primary control must be malfunctioning. I just need to know which contacts to check when the problem occurs again.

On 2022-01-27 by Inspectapedia Com Moderator - don't keep pressing that reset button or you risk a puffback explosion

@Wendell,

It sounds as if your burner is not operating properly, possibly needing cleaning or adjustment.

Unfortunately, while it's mechanically easy to change an oil filter and nozzle, with modern high speed oil burners (3450 rpm motors) it is not possible to adjust the system properly without both training and proper equipment to measure smoke, CO2 or O, stack temperature, and draft.

Also, having done so myself, I warn that it's easy to make a small mistake changing a nozzle that leaves an air leak in the piping (and oil leak when the fuel unit is running), or a damaged thread that causes an oil leak, or a bumped or bent electrode that changes the gap or position of the electrode tips.

ANY of such hard-to-spot snafus can result in an improper flame, sooting, and sending the burner off on safety-reset.

Watch out: if you can re-start the burner and it keeps running for a complete heating cycle, then you may limp along while you wait for a service call. But don't keep pressing that reset button or you risk a puffback explosion.

see

OIL BURNER SOOT & PUFFBACKS

On 2022-01-27 by Wendell

I have an oil fired crown direct vent with a Carlin ez-1 burner. The unit is 17 years old. In the last week the boiler shut off and would not restart on its own. The 1st time the circulator was running , the boiler was off and there were no lights on the control unit.

I flipped the emergency-off switch ( just guessing) and the boiler started back up. 4 days later the same thing occurred except this time when I flipped the switch to on, the red light on the control unit was on. I pressed it once and boiler fired up.

I did change the filter and nozzle 2 weeks earlier for maintenance. I’m stumped as to what to check that causes the shut-off condition

On 2022-01-19 by Alan

@Inspectapedia Com Moderator, Thanks, I will go that route first.

On 2022-01-19 by Inspectapedia Com Moderator - temperature sending probe may be in poor thermal contact

@Alan,

Probably not - though a defective probe could I suppose send a false "high temperature" reading.

The fact that your burner is going off on reset and that you have to push the reset button tells me that cleaning and/or adjustment or repair are needed.

Don't defer that service or you might risk not only loss of heat but a puffback explosion of incompletley-burned oil from sloppy starts or stops of the burner.

On 2022-01-19 by Alan

@Inspectapedia Com Moderator, Thanks, appreciate the help.

Could the temp probe also cause the burner not to start when the boiler temp is low even though the thermostat calls for heat, the relay pulls in, the circulator is on and the aquastat b terminals read 120v but the burner does not kick on. (a reset start will turn on the burner)

On 2022-01-19 by Inspectapedia Com Moderator

@Alan,

The temperature sending probe may be in poor thermal contact in the sensor well, or may be failing.

On 2022-01-19 by Alan

@Inspectapedia Com Moderator,

Thanks for the reply. Settings have never changed over 20 years. High is set at 185 and I dont believe there is a low.

I also occasionally get a variation as to what temp it shuts off at. Usually it is around 180-185, but once in a while it will stop at 10 - 150, and this morning shut off at 210. this was the highest I have seen it.

Could it be the aquastat thermocouple or something else?

On 2022-01-18 by Inspectapedia Com Moderator - Becket Burner not starting

@Alan,

Start by checking the Aquastat settings to be sure they're correct and not "crossed" (HI too close to or even below the LO)

see AQUASTAT HI LO DIFF SETTINGS

On 2022-01-18 by Alan

Becket Burner not starting under certain conditions. System is oil fire hot water baseboard with an indirect water heater. 3 zone system. I have a Becket AF, L8148A aquastat, R8184G cad cell relay.

Once the burner is started, it will cycle to the high limit and stop, reading 0 volts on C and B terminals of aquastat.

If Thermostat calls for heat and boiler is above 150-160 it will start and run correctly.

If the thermostat calls for heat and the boiler is below below 140 I get 120 volts across B and C terminals, the circulator turns on but the burner does not. If I push the reset button the burner starts, and runs up to temp.

Any suggestions, Aquastat or Cad cell relay? Thanks

On 2021-12-18 by Inspectapedia Com Moderator

@Pete,

There could be any of a number of causes of "no flame' at an oil burner, such as more-detailed causes of

• no fuel
• bad igniters or transformer

Step through the diagnostics on the page above and let us know what you find

Watch out: if oil is being delivered DO NOT keep pushing the reset button and trying to restart the oil burner as you could cause a dangerous PUFFBACK explosion

In the Recommended Articles see OIL BURNER SOOT & PUFFBACKS

On 2021-12-18 by Pete

Furnace motor starts but will not fire

On 2021-12-06 by Inspectapedia Com Moderator

@Linda,

If "cheap" heating oil means dirty or contaminated with water, yes. Contaminated heating oil can foul the oil burner and lead to both loss of heat and additional costs to service the burner.

If the "cheaper" oil is identical to the expensive oil, no, it wouldn't hurt the oil burner.

Keep in mind that in some communities, ALL of the heating oil, regardless of who is re-selling it to you, comes out of the same physical storage tank serving oil companies in that area, so all of it would be identical.

The differences in oil retail prices in that case may be variations in the time and rates at which oil companies bought their share of the oil in the master tank.

Another price difference is that even though the oil being sold and delivered to you was bought and delivered and stored in the big oil depot tank six months or a year ago, SOME oil companies, perhaps many of them, charge you an amount per gallon based on the current (increased) wholesale heating oil price - the cost to them of replacing the oil they are delivering .

Watch out though: in other communities, different oil companies may be getting their oil from different suppliers or may be storing it with different care.

On 2021-12-06 by Linda

Can cheap oil hurt heater

On 2021-11-29 by Inspectapedia Com Moderator

@reset button trips after at temperature,

Do I understand correctly that you changed the aquastat or cad-cell relay on which the reset button is popping?

If so and the control is thus new and correctly wired, and the cad cell is new and clean,

• the cad cell might not be properly-placed to see the flame
• there may be a fuel delivery or oil burner tuning problem that's shutting down the system
  

The assumption is that when the temp drops 5 degrees the aquastat is trying to turn the burner back-on. I can't think of a condition that would commonly trip the reset button if a burner was not trying to run.

Also check the Aquastat Settings (See the Index to Related Articles to see the best aquastat settings)

On 2021-11-29 by reset button trips after at temperature

I have an intermittent problem that when you hit the reset button the burner will run until 190 degrees and stop then with a drop of 5 degrees the reset button trips with no demand.

Any idea? I have changed the cad cell and control box still does the same thing

On 2021-09-10 by Inspectapedia Com Moderator

@Mike,

Could be a bad cad cell, and of course that's an inexpensive and easy part to swap.

Look also for a loose or corroded electrical connection

and of course to properly set up the system to be sure that it's running clean requires training and special equipment such as to measure CO2, oxygen, smoke, temperature, and draft.

On 2021-09-10 by Mike

Electric oil burner furnace New York Honeywell Beckett I’m thinking it is the cad eye????

The furnace room is fine but it stopped heating up almost like it’s not calling for it. If I manually starving it will run just fine most of the time then it’s OK for a few days but sometimes I have to keep manually starting it.

It won’t be run for 10 minutes and then stop before it’s up to temperature then I will have to restart it again. That’s only once in a great while.

Usually once I need tostart it, it will take the temperature right up and the furnace may run fine for two days then it will stop calling for it again and won’t heat up the water to correct temp again.

On 2021-04-15 by Inspectapedia Com Moderator

@Jim M.,

Yep; a test of the ignition transformer may find a weak spark that ultimately leads to loss of heat; it's pretty easy to demonstrate in a low-tech way using a screwdriver if the technician knows-how.

And a failing transformer will eventually fail to ignite the oil, leading to the burner turning off on safety-reset.

But when an oil burner hums and doesn't start running, I suspect a bad burner motor

Is there a reset button on your motor? If so, when the motor cools off see if you can push it in.

Keep me posted.

On 2021-04-15 by Jim M.

Is there such a problem as a weak ignition transformer when the oil burner runs just fine and only needed annual cleaning?

On 2021-03-06 by Inspectapedia Com Moderator

@huck finn,

Using the on page search to scan InspectApedia for "oil burner humming noise" we find

OIL BURNER HUMMING NOISE

that lists common causes and repairs for a humming oil burner

On 2021-03-06 by huck finn

I have a thermo pride oil furnace about 20 years old , yesterday every now and then I could hear a humming noise like when a bad breaker is humming or the refridgerater kicks on that only last about 2-3 seconds and then stops?

I didn't relate it to the furnace until this morning when it was a little cool in the house by a couple degrees and when I checked the furnace it was not running?

it ran all night but stopped in the morning, I turned the power off to see if it would maybe cool down? when I turned it back on it hummed for 2-3 seconds and stopped and nothing???

On 2021-02-22 - by (mod) -

@Frank,

Is the burner turning back on after it has shut off shortly after the thermostat was calling for heat?

If so then look for blocked air flow, dirty air filter, clogged heat exchanger, etc.

On 2021-02-22 by Frank

Thanks. Shortly after I posed this question on here I pulled the eccobee thermostat and reset it and it did not happen again until today. Same thing, but we came on several times when it wasnt supposed to and when I moved the call point up ot can on as it was supposed to. So frustrating. Guess I'll have to get HVAC folks out. Again.

On 2021-02-21 - by (mod) -

@mark,

What needs replacement? The oil pump - ok fine. The whole heating system? Wow!

On 2021-02-21 by mark

I have an oil boiler with a power vent. the power vent turns the burner has spark but no power to the motor that turns the oil pump. two service companies said it's twenty years old and needs to be replaced. I can afford to pay for repairs but can't afford to guess at buying parts.

All wire connections are good. Any ideas that could help would be great.

On 2021-02-04 - by (mod) - HVAC contractor says it the thermostat, not the furnace, but the thermostat folks say nothings wrong

Frank

That is an interesting problem involving the ecobee smart thermostat.

I'm not sure If I'm on the right track but certainly one thing I would want to eliminate would be a problem with the thermostat wires themselves such as an intermittent short or a loose or poor connection.

When you turn off heater thermostat and your heating system still turns itself on, it's entirely possible that that's because the thermostat wires are touching somewhere en route.

On 2021-02-03 by Frank

Hi, I have an unusual and intermittent problem. The HVAC contractor says it the thermostat, not the furnace, but the thermostat folks say nothings wrong. I have oil burner with hot air heat and an eccobee 3 lite.

This has happened 2 nights in the past few week. The oil burner will come on and cycle off when the room temp is several degrees above the set point. The fan will not come on. Typically the fan will come on before the burner.

Last night while the thermostat was set to 60F and it was 64F in house, the oil burner started and stopped every 7-8 minutes.

When I moved the set point up above the temperature, everything worked fine, air handler came on and then the burner and heat worked fine.

Later in the night the program turned the thermostat back down to 60F and it started calling the burner in again when the temp was several degrees above the setting.

I turned the heat off on the eccobe and the burner still tried to turn on every 7-10 minutes with the heat off on the thermostat.

To summarize, the heat and fan seem to work fine when the temp is below the thermostat setting and the heat is supposed to come on.

The air handler always comes on first then the burner kicks in. However, sometimes when the room temp is several degrees above the thermostat set point and the heat should not come on, the oil burner is called, starts and runs for about 30 seconds.The air handler does not come on.

Last night this happened even when I turn the heat off on the eccobee thermostat. Thanks.

On 2021-02-04 - by (mod) -

Bob,

Your supposition is a good one, and to check it out in pretty easy. Just Watch What Happens at your air handler or furnace when there is a call for heat.

If the burner comes on in the limit switch rotates all the way around to the high limit and turns the burner off with no fan operation,, that would tell you that your fan is not coming on when it ought.

But this line is inconsistent, since you're describing correct furnace operation most of the time.

It also doesn't address the question of why your heat is running at above the thermostat set point.

It was that that made me look for a wiring defect.

On occasion I have found very sensitive connections that were made depending on temperature or even depending on the position of a thermostat control.

Apologies that I can only guess from such a remote location. In my experience, 100% of the time that we've ever gone to a property we found other critical diagnostic information that we just didn't know about it ahead of time.

So for case like this, I want to start by eliminating the things that would embarrass us later such as a shorted wire or bad electrical connection, perhaps followed by a bad relay or control board.

On 2021-01-13 by (mod) -

Bob

There is a too-long list of possible causes for the oil burner to go off on reset intermittently.

Techs usually check these things in roughly this order:

1. a dirty cad cell sensor in the oil burner gun or a failing cad cell relay
2. a dirty oil burner that needs cleaning, nozzle replacement, oil filter change, oil screen change in the fuel unit, tuneup including combustion air adjustment and a check on pressure at the oil nozzle output line
3. clogging of the oil delivery system such as crud in the oil tank that blocks an oil line, filter, screen, or nozzle
4. a failing transformer on the oil burner - gets hot and stops working
   
   Subtle problems like
5. an air leak in the fuel piping or right in the fuel unit itself
6. Other causes are described on the page above
   

There is a long list of reasons that a burner could be having an issue but the key here is this is only happening when the room temp is several degrees above the set point or even when the thermostat heat setting is off. The burner should not even be trying to come on.

When the room temp is below the set point the burner and fan work fine.

Is there any kind of relay issue that could cause the burner to come on when its not being called by the thermostat or even when the thermostat is off or does this seem like it has to be a thermostat problem? I suspect it goes off because the fan isn't coming on.

On 2021-01-13 by Bob

My fuel oil furnace is having an intermittent problem. When it lights it does stay on until the desired temperature.

It's been solid throughout the year (2020) until recently when I had to press the reset button to get it going (I do know not to press the button more than once or twice). Twice in 1 week I had to press the reset button.

I had a tech come out and do a maintenance on it as well as attempt to troubleshoot the issue.

They still have not found the problem. After the maintenance, I had to press the reset more often. Overnight, I would wake up several times just to hit that reset button.

When it doesn't work, sometimes I do hear the motor running attempting to light the furnace, but other times I hear nothing at all. Once it stays lit, it works great.

Everytime the tech was here, we were able to get to light, turn off, turn back on just fine. Maybe once things cool, it has the problem?

On 2020-12-09 - by (mod) -

John

Probably not.

I was looking for the case in which the burner runs, plenum heats up, fan starts, air flow is too weak, plenum gets too hot, system shuts down.

your case is probably a burner cleaning and adjustment issue, or potentially a bad wire, connection, relay, or control board.

By "Stack box" and by your identification of your primary control as the Honeywell RA117A, you're referring to what I call a stack relay - a primary control that monitors temperature in the flue vent connector, detailed at

STACK RELAY SWITCH

You will want to take a look at that article because it describes re-stepping the relay control - it an be a bit finicky. Sometimes that's all that's needed to get the oil burner running properly again.

See

• STACK RELAY RESET BUTTON OPERATION
• STACK RELAY INTERNAL RE-STEPPING the CONTACTS

A stack relay is less reliable than a modern cad cell primary control, and can usually be replaced by a cad cell relay. There's a bit more to do - adding a cad cell eye and bracket in the burner assembly but any oil heat service tech ought to be able to do that.

Do me a favor and post a sharp photo of your stack relay as installed, and in a separate comment (one image per comment) a photo of the control with its cover removed. Be sure to see the warnings and details in the article I cited above.

On 2020-12-09 by John

Upon further review, it's starts and stops before the blower ever gets going... Would that still be a filter issue... Also, if it is the stack box, is there a quick fix there... Those things are hard to find and very expensive... Thanks again for the help! It's a Honeywell RA117A

On 2020-12-09 - by (mod) -

Watch the limit control dial - if the furnace is shutting off on the HI LIMIT then it's overheating - possibly a dirty air filter, blocked air flow in ductwork, even a bad sensor.

On 2020-12-09 by John

Oil furnace short cycles for a bit, then will kick on as normal for a bit, then go back to short cycling. Been through everything with this "A Christmas Story" type furnace, just hoping it's something simple that I'm overlooking... It has an oil primary stack mount control, which looks ok. Thanks in advance.

On 2020-12-05 - by (mod) -

Keith

It will be diagnostic to see if we can pinpoint the source of the buzzing sound. It's possible for example that what is buzzing is a relay which would possibly mean that we have a bad relay on a control board. If the burner never starts or circulator never starts because a relay has failed then of course the heater won't turn on.

Try pulling the cover off the control to see if you can see or hear a buzzing relay. If you're not sure what that looks like you can tell me and I'll post a photo for you.

On 2020-12-05 by Keith

Oil furnace will work fine for hours then all of a sudden will not start has buzzing noise and then cad cell relay kicks out . Motor circuit breaker stays in not kicking out , cad eye new, cad relay new , igniter 1 year old . Burner is in my hunting camp it's a wayne eagle 1

On 2020-11-25 - by (mod) -

Let's start by looking through the items on the page above. You got fuel but you could still have a bad nozzle

On 2020-11-25 by Anonymous

My oil-fired steam boiler in my residential home will only run for a minute after a manual re-fire. I just purchased fuel and changed the fuel filter within the last two days, so I can confirm that neither of these are the issue.

On 2020-11-06 - by (mod) -

That sounds like your oil burner needs cleaning and adjustment because it is tripping off on safety reset. Don't keep restarting it or you risk puffback explosion

On 2020-11-03 by Johnny

Oil burner comes up to temperature but won't restart

On 2020-09-26 - by (mod) -

Joe

A service Tech will measure vacuum on the oil line supplying the burner and from the determine if the line is probably clogged. If the line is clogged or if the oil filter is clogged it needs to be cleared

On 2020-09-26 by Joe

I have a 550 gal underground oil tank. I started having issues recently with the burner regularly kicking off. If I disconnect the supply and return lines to the underground tank and feed them from a local bucket of oil instead, the system runs fine. Any suggestions to repair so this run properly from the underground tank?

On 2020-06-04 - by (mod) -

Is this a Taco circulator for an indirect hot water heater for hot water used for washing and bathing?

On 2020-06-03 by Anonymous

But there is no hot water

On 2020-06-03 - by (mod) -

Mike

What you describe may be normal;

check the boiler temperature on the temperature gauge right on the boiler itself. If the boiler water temperature is near the HI setting on the boiler's aquastat then the system is doing what it's supposed to.

Leaving out a few details it's like this:

The circulator keeps running as long as there's a call for heat;
The burner will turn on and off depending on boiler temperature.

On 2020-06-03 by Mike

My Taco Valve control system call for heat, my burner kicks on then after 5-10 min it shuts off. But the Taco is still calling for heat and the Circulator pump is still running

On 2020-05-21 - by (mod) - oil boiler that shuts-off (failed to fire) often like once or twice a week.

IS

How old are your oil tank and oil piping? There could be a sludge problem that's either clogging and blocking fuel delivery or sooting up at the burner.

A vacuum test on the oil line can tell you if there's a blockage, and inspection inside the oil filter cartridge can tell you if there's a lot of sludge, water, or crud.

On 2020-05-21 by ISJ

I have oil boiler that shuts-off (failed to fire) often like once or twice a week. I have replaced first oil filter, nozzle and adjust electrodes, clean flue pipe and boiler coil as a regular maintenance.

But that didn't help.Than I replaced the burner control with one that you can read in real time the CAD cell and checked what amps pull the motor and it was less than it's name plate.

Also replaced the CAD cell just in case after that, and also the oil pump because has the shut off valve build in.

So far the boiler shuts-off when it wants and every time when you press the reset button it starts and run fine for days with no problem. I feel lost. What could be the issue?

On 2020-05-20 by Dan - The furnace would burn but it was short cycling,

Hi, my oil burner has been showing multiple symptoms with no one definitive problem, getting very frustrated. It is a becket oil burner installed in a modular home so it's set up as a downdraft furnace (blower on top of heat exchanger)

The first symptom was noisy (bangs and clatters) and eventually burner locking out on flame safety. I then changed the fuel line filter, checked for sludge in both tanks, both were minimal.

I also changed the screen in pump. Replaced burner nozzle, checked electrodes and set them properly. Replaced CAD cell and made sure the ignition system was producing a strong arc. I also cleaned and oiled the blower. After all that, the second symptom started.

The furnace would burn but it was short cycling, heat would run for a minute or two, hit high limit, shut off, repeat.

I inspected the flue which was clear however the flue connector that connects the exhaust to the firebox was in rough shape and had rusted away in the back side which the falling piece of rusted metal had effectively clogged the manifold style flue connector.

I replaced the flue connector. After replacement, the furnace now fired for longer with no short cycling, however, after about two minutes, it was tripping out on flame safety, even though I could clearly see the furnace had solid flame.

I rechecked the CAD sensor's resistance to make sure it's working properly, it was.

I also noticed that my replacement flue connector wasn't air tight because I had cut out bad metal around it when I removed the old one. I took hvac high heat aluminum tape and sealed the area where the exhaust and flue meet. I also blew out the line to make sure I didn't have any clogs. After I did this, the burner struggled to fire.

When it did fire, the flame was weak and tripped out quickly. This is the current symptom I still can't figure out. I thought maybe it was air/ fuel mixture problem, unfortunately, my burner for some reason or another has no air shutter adjustment to adjust intake air. I am at a loss for what to check next, any thoughts would be GREATLY appreciated.

On 2020-05-09 - by (mod) - never keep pressing the reset button

Mark

never keep pressing the reset button - you risk a dangerous puff-back explosion.

Typically the primary controller is using a flame sensor to see that the burner is working properly;

if it doesn't see a flame it shuts the system off.

Sometimes the problem is a dirty or sooty cad cell eye - cleaned off or replaced. If that doesn't fix the problem then the system almost certainly needs cleaning and adjustment.

On 2020-04-22 by Mark

Oil fired heating burner will only fire up when I press the reset button and will only run for a few minutes and then stop. Any advice welcom

On 2020-03-23 - by (mod) -

Glad to assist, do keep me posted.

On 2020-03-23 by Cliff

Thank you for the reply.i will have the system serviced

On 2020-03-23 - by (mod) - lights dim when oil burner starts

Cliff

I expect your technician will check

- that the electrical panel, circuit breakers, wiring, are in good condition and working properly

- that the furnace electrical circuit is remaining on and at proper voltage

- that the furnace blower and burner motors are not drawing abnormal levels of current (dimming house lights, dropping power)

- that there are no loose electrical connections

- for the system being turned off by a safety control

- and then will check for a relay or control board failure

On 2020-03-23 by Cliff

Sometimes when furnace starts it powers downs furnace and 1/4 of power in house. after minutes to 30min will start up on its own. zero breakers trip? Power company verified outside lines ok?

On 2020-03-22 00:43:56.076422 - by (mod) -

Kim:

The cause of your oil burner's refusal to run is likely to be one of those listed on the page above.

In any event, if you are sure that electrical power is ON to the heater and oil burner then it's time to ask for help from a service technician.

On 2020-03-21 19:02:45.134624 by Kim

Fan runs continuously, blowing cold air, beckett no lights, does nothing with reset button. Oil tank full

On 2020-03-02 - by (mod) -

Anon

We have a separate article series on this problem of a boiler that won't go off starting at HEAT WON'T TURN OFF

Please take a look and make follow-up comments or questions on any of those pages and we'll continue.

On 2020-03-02 by Anonymous

What boiler comes on but will not go off again what might be the problem

On 2020-03-01 - by (mod) -

Charles that sounds to me as if the system is turning off because of a safety control such as a sensor that detects a poor burner flame.

Don't keep pressing the re-set button on the burner. You can press it ONCE - if the burner starts and runs for 5-10 minutes or longer you can have heat while you are waiting for your heating service technician.

But if the burner doesn't keep running do not keep pressing the reset button as you risk a dangerous puffback explosion.

On 2020-02-29 by Charles

My riello burner starts then stops after 5-10min with no heat in the radiators, and not starting anymore I can feel hot in the pipe around circulating pump. Right now it stopped

On 2020-02-25 - by (mod) - oil burner has been shut down on "safety"

That sounds to me as if your oil burner has been shut down on "safety" - indicating a flame or burner malfunction that needs to be repaired. It may be as simple as an oil burner cleanout and tuneup.

Watch out: do NOT keep pressing the reset button. If the burner won't keep running after pressing the reset on the primary control the risk is that you keep dumping incompletely burned fuel into the combustion chamber, ultimately leading to a dangerous PUFFBACK explosion.

On 2020-02-25 by Don

The signal to the heater does not activate the heater. However when I press the reset on the primary control the heater starts and the hot water pipes get hot and begin to distribute heat. The heater does not start from the thermostat signal. Thermostats [I have three zones] are working properly.

On 2020-01-11 - by (mod) - pressing the reset button on the burner

Luis

If pressing the re-set button on the primary controller (JUST PRESS IT ONCE) doesn't get the system running, check the step by step diagnostics starting at the top of this page;

If that doesn't tell you what's wrong it's time to call your heating service tech.

On 2020-01-11 by Luis

My boller no turn on in have red light in the honey well ????thank u

On 2020-01-05 - by (mod) -

I can only guess with so little information, but it's possible that your blower is not running.

If the oil burner turns on and heats up the heat exchanger but the blower fan doesn't turn on to push air across at the heat exchanger will get hotter and hotter until the limit control switch reaches its emergency shut off and it will simply turn off the system. So it sounds as if you need repair. Possibly to the blower or blower motor.

However before calling the service repair technician you might open the blower compartment to expose the fan assembly. If your blower motor is driven by a fan belt between the motor and the actual rotating fan it could be that the belt is broken or has come off. That would be an easy repair

On 2020-01-05 by Jerrica

My furnace will start up but it will shut off and not blow no air and it will try to come on like 2 times then stop and it was working good today what could be the problem?

On 2019-12-27 - by (mod) - Do You Want to Disable the LO and DIFF settings

Anon

at AQUASTAT HI LO DIFF SETTINGS

In that article be sure to read also the section titled "Do You Want to Disable the LO and DIFF settings on a Boiler that Does Not Use a Tankless Coil for Domestic Hot Water?"

And then read AQUASTAT LO & DIFF DISABLED

On 2019-12-27 1 by Anonymous

i am not using my water heating element.what settings do i use on my aquastat?

...

Continue reading at HEAT WON'T TURN ON or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see OIL BURNER WON'T RUN FAQs for questions & answers posted originally at this article

If the oil burner starts but does not run properly see these

Recommended Articles

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• BUILDING EXTERIOR Oil Burner Trouble
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• OIL TANK EFFECTS on OIL BURNER
• BOILER / FURNACE ROOM TROUBLE SIGNS
• OIL BURNER VISUAL INSPECTION
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• OIL BURNER SMOKE TEST
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• OIL BURNER MANUALS
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• OIL BURNER NOISE SMOKE ODORS - home
• OIL BURNER NOISE / ODOR DIAGNOSTIC INDEX
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• OIL BURNERS, RETENTION HEAD
• OIL BURNER SOOT & PUFFBACKS
• AUDELS OIL BURNER GUIDE, INSTALLING, SERVICING, REPAIRING - an online PDF of a complete oil heat service text book

Suggested citation for this web page

OIL BURNER WONT RUN at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING OIL, OIL BURNERS, OIL FIRED HEATERS, OIL TANKS

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