Intermittent pulsing, sputtering, shut off of oil burning forced hot air furnace

clizotte

Hello all. We are growing increasingly frustrated trying to diagnose intermittent issues with our oil furnace. We have had a couple guys come out to diagnose, but it seems to end without finding the source of the problem and pushing us toward buying a natural gas upgrade. We have lived in this home for 4 years and have had annual servicing up until last fall when we switched away from IIrving service. We hired a new tech this fall for our annual service and have had undiagnosed problems persist. Having a hard time finding people knowledgeable and willing to fix instead of replace. Bangor Maine area. 

Maintenance: We have electric hot water so system does not run in the summer. Kept tank above 1/2 to prevent issues. Religious about swapping air filters. Chimney cleaned. Kicked on 1-2 times a month in the summer to check functioning. All seemed fine.

Service: New tech came to do annual cleaning, changed igniter and nozzle, ran no tests that I observed. Furnace sounded sputtery when he left but stayed on. Asked him to come correct the sputtering and after leaving, it worsened. Started to shut off after sounding like it was cutting off/coughing. We then asked a new company to come by after loosing confidence. They switched to a new nozzle, checked the oil line, checked the igniter, checked pump pressure, checked exhaust, and more I didn’t completely comprehend but it was running great while he was here so he couldn’t find anything wrong. He mentioned switching out the fuel pump but he couldn’t be sure if that was the culprit without observing the problems. We don’t want to randomly switch parts and throw money at it if we really are working with a dying system…however it would be nice to know what’s going on. He did mention noticing oil blowback onto the nozzle. I’ve managed to catch a few videos of the issues which are easier to show than describe but it seems I can only post photos. Sounds as though the flame chokes out, or almost goes out, then either the green light flickers off or completely shuts down red. If it manages to just flicker, it then seems to aggressively cough(?) but stay ignited. Restarts automatically after a red light time period. It does also make the house smell of oil after the red light flashes and the fan continues to blow. Always happens mid cycle, never had issues igniting at the start. Happy to answer any follow up questions as best I can. 

BRader

You need to find a competent tech that can test and diagnose that burner. There could be a number of factors leading to the problem you're having. It sounds like poor combustion setup, but without being on site it's hard to tell. Get someone out there that will check the flue for obstructions, check draft, perform a smoke test, and do a combustion analysis. Oil pressure and nozzle selection also needs to be verified and changed/adjusted as necessary. There's a lot more to properly setting up an oil burner than just swapping the nozzle out. On that burner, the Z dimension has to be set as well. Unless the heat exchanger is compromised, you can probably get some more life out of that unit. Good luck. I hope you can find someone local that can accurately diagnose and repair it.

clizotte

Thank you, any chance you know someone you would recommend way up here?

clizotte

Was able to post my videos here. Hope this doesn’t go against any rules.:/ https://www.reddit.com/r/hvacadvice/s/rg1ItS23hI

STEVEusaPA

What happened to the first tech you had? Seems like you had no problems until you switched.
No parts should be changed until properly tested to prove they may be defective.
Can’t tell from you're video, but you’re obviously losing flame.
Is that from poor set up, slipping coupling, and/or a combination of things?
If I had to fix this, I’d probably start over.
First pull it apart to make sure the boiler is clean. Pull the burner to make sure the chamber is clear, no problems with the target wall, etc. Check clean flue pipe to chimney base. If daytime, look up chimney to at least make sure it’s clear.
Verify end cone is intact. Set Z dimension.
Verify proper nozzle, and pump pressure.
Change filter and pump strainer.
Check fuel pump properly with pressure and vacuum gauge.
Power purge, fire up, full combustion test.
All of that should take about an hour.
Did you check 'Find a Contractor' to see if someone on this site is close?

clizotte

Hey Steve, thank you for your detailed reply. Our previous tech retired and we switched oil companies. I will check the “find a contractor” We are somewhat rural, and most techs are booked out months on the off chance they are even taking on new folks. So I guess I assumed it would be futile. I know for a fact that at least a majority of these things were checked but it was checked while running properly not during these bouts of issues. There has been no observable pattern so we haven’t been able to call him back to “trigger” the issues. I don’t necessarily think that the second guy we had check it out, wasn’t qualified, but the issues are so intermittent he didn’t want to (like you mentioned) swap things out without finding the failure. Kinda stuck until things get more frequent, or we just loose patience and cave into the pressures of upgrading the whole system…which we don’t really want to do at least until April when we can swap to natural gas. 

mattmia2

They should have given you a report with the combustion and draft numbers on it. Just because it isn't doing it doesn't mean it is burning properly, that is where instruments and knowing how to use them comes in.