Furnace Mis-firing on and off

jebigham

I have a 20+ year old Lennox oil fired hot air furnace. This is the 2nd time in 3 years it chugs like a car firing on and off. Furnace is serviced every year. Last time a Honeywell control panel was replaced. Any ideas why again? Attached video cloud link.

https://share.icloud.com/photos/056wAmfes8dS4WS2MHRYqCm_w

SuperTech

I'm not sure but that seems dangerous. You should shut it down until your service provider can get there. Ask them to install a modern primary control with interrupted ignition. 

Now that I think about it I've seen the Beckett AFII burner you have do that when the ignition transformer cables to the electrodes are damaged and arcing against the burner.

EdTheHeaterMan

The Primary control model number R8184M is the problem. This is a problem in the control flame sensing circuit. I am not a big fan of that control. Can you tell me the model number of your Lennox furnace so I can look up the wiring diagram? You need to upgrade to an electronic primary control. The problem is that the R8184M has a 40 VA transformer that other components on your Lennox furnace use. So the standard electronic primary controls like the Carlin ProX 70200 will not be an exact wire for wire replacement.

With your Lennox wiring diagram I can offer your technician the necessary upgrade in order to replace that Dinosaur primary control with something that will not fail in the way your control has done 2 times in the last 2 years.

EDIT: I have upgraded a furnace like this in the past. I just need the wiring diagram for your furnace to let you know how.

STEVEusaPA

Agree with the above. While checking wiring for a loose connection, I’d also take a look at the high limit, fan/limit.
To me if it were just flame dropout, or coupling slipping, I’d expect the burner to lock out.

HVACNUT

Same as above. Either faulty contacts in the M control, or something is preventing TT from staying closed.
Can you take the cover off the electric to the left of the burner (Shut off the power first) and post a pic of what's there? I'm pretty sure there's a control board in there so I don't understand why the M is even being used. 

Is there air conditioning? If yes, in the zone panel, is Rc,Rh jumped, or is there a separate wire to each? 

EdTheHeaterMan

Looked all over for the Lennox with the the R8184M in the wiring diagram. Could not find it.

Big Ed_4

Jump out TT and maintain a watched electrical meter on black and white leads on the primary control ( red button ). If burner runs steady check your thermostat circuit . If the primary receives a steady voltage and relay still flickers replace the primary .If there is no AC on the furnace you can replace with a cheaper non 40VA primary control... If you notice the meter flicker you will need to check deeper ..