Boiler Keeps Cycling Gas Burner

BrianT1077

Hello everyone! Please check out the video I attached with this post. I noticed tonight that my boiler keeps cycling the gas burner over and over within minutes. What would be causing this? If you need any more details, please just ask. Thank you again!

https://youtube.com/watch?v=OanYfRDTZRA&feature=em-upload_owner

JUGHNE

First thing I would do is clean flame sensor and check wiring connections from the module to burner.

newagedawn

take the front panel off so we can see the flame, could be roll out switch, could be gas valve, could be the ignition module, how old is the unit? the grey ignition module is ole they havnt been grey for a long time, flame sense could be dirty or weak

BrianT1077

Thank you guys for your advice, of course it is not acting up now since I have been watching it, but I will get a more in depth video hopefully tomorrow that you can see.

BrianT1077

Update! The boiler started cycling the gas burner again today when I got home so I was able to make a video with the flame. Check it out:

https://www.youtube.com/watch?v=eskd0k_AGdg

MilanD

By way of how quickly it's cycling, I'd check tstat wiring, tstat itself may also be bad. I had this same thing on the hot air furnace, changed tstat, problem solved.

Then, check other wiring: ptrol, flame sensor, etc. If it isn't tstat, you have a loose wire somewhere, or a dirty/faulty flame sensor.

JUGHNE

I wonder if your main burner isn't knocking the pilot flame out or away from the flame sensor. The pilot almost looks to go out and then relight.

I would clean pilot, spark, flame sensor and make sure ground from burner to module is good.

Steamhead

What @JUGHNE said.. It's not the thermostat since the spark comes on when the flame goes out, indicating the thermostat is still calling for heat.

JUGHNE

And if there was a vent damper motor, that might have to cycle if any other control was cycling.

MilanD

I'd still jump tstat to rule it out.

j a_2

MilanD said:

I'd still jump tstat to rule it out.<
Jump out the t stat...that will answer that...Check for loose or corroded wires....Test all the safety features...u can jump them out for testing purposes only...shake all the low voltage wiring when it's up and running....Best of luck....

BrianT1077

Hi everyone! Thank you for the input. I am going to try some suggestions out. BTW it does have a vent damper motor but that does not close or attempt to close when the burner keep cycling.

BrianT1077

I jumped out these 2 sensors one at a time and the problem still exists.

JUGHNE

If either of those sensors opened the spark would not continue to buzz. It is fairly clear that the flame sensor at the pilot is not transmitting presence of flame back to the ignition module.
It needs to be clean and there needs to be a good ground connection back to the module.

What is that dripping tar look substance above the burners?

BrianT1077

@ Jughne, that tar like substance has been there since it was installed, it is like a sealant of some sort.

Dave0176

Hi Brian I've had this issue before and I cleaned the Flame sensor with nail polish remover (because of the acetone) and that works great. However if the issue returns then you have to replace the flame sensor.

JUGHNE

Clean first and retry......if for some reason the flame sensor is not in the fire, as mentioned pilot too small when main comes on perhaps.
It must have the flame of actual fire to conduct the electric signal back to the safety/ignition module to keep the gas on.

BrianT1077

@Jughne, @Dave0176, Thanks guys, later on I am going to check the flame sensor and clean it. I hope it is just dirty, shouldn't need to be replaced, boiler was installed in 9/2015.

BrianT1077

Hey everyone! Well tonight I cleaned the flame sensor with nail polish remover per @Dave0176 suggestion, and also found some junk on top of the burners, see pics below. So I took them out, cleaned and shop vacuumed them, then I also vacuumed out the combustion chamber. Note on the 1 burner there was a mound of junk fairly close to the flame sensor. Outside temps are warmer now, but I did crank up the t-stat for a bit and test ran everything, so far so good. We will see, I will keep you posted if anything happens with what little left heating season we have. Thanks for the advice so far everyone!

j a_2

Good job