Weil McLain EG-50 won’t start

esdad697

https://youtube.com/shorts/5LOpF6T8U7g?si=2xYd4MNbVKL5rGFs

Gas furnace won’t start intermittently. It is most noticeable in afternoon and evening. There is usually heat in morning. 

You can hear a click and the gas flows for 10-15 seconds. It doesn’t ignite. The gas flow stops. You can hear this in the video. 

What is likely cause?

109A_5

Hello @esdad697,
Is the spark getting to where it needs to be ?

esdad697

Top pic is bottom view. There is a thing with 2 yellow wires and a thing with 3 wires. Which should generate spark? Does panel have to be removed to see spark? Can it be lit manually?

109A_5

Hello @esdad697,
Sadly your video is simply too blurry, too much panning motion in the beginning to properly see the wires from the control box. And you have not posted any clear pictures of the whole front of the boiler.

"2 yellow wires"
This is the flame Rollout TFE (thermal fuse), probably good, since the start up process is getting as far as it is.



I think the Orange wire is the ignition wire (high voltage). At its very end (pilot assembly) it sparks to light the pilot, the presents of the pilot is then sensed by the White wire. If all is well so far, the gas is turned on to the main burner and the pilot flame ignites the main burner. If something is missing in this process it stops and retries, some systems the retries are limited.

If the spark is not at the very end of the Orange wire at the pilot assembly (arcing elsewhere or just not at all) the process stops, since a lit pilot is not sensed.

109A_5

Hello @esdad697,
Is this just poor lighting or is there some dilapidation of the wire going on here. Maybe a better quality close up picture would help.

esdad697

I had a service call today. Service guy temporarily removed the igniter assembly and sanded the sensor. He is installing a new sensor tomorrow.

Thanks for the help. Reading other posts suggested it was the igniter, and caused me to take a video. The video was helpful, because the boiler started when service guy was here. The video let him see a failure.

esdad697

So I still have the issue, though less frequently. The past few days have been good, but on Sunday at 10am, it was about 60 degrees.

The behavior was the same as before:
- furnace would click and you could hear light gas flow
- about 12 seconds later it would go off
- it never goes fully on

Could this still be an issue with the igniter? What can I check or do?

STEAM DOCTOR

You really shouldn't check anything. You should either have that tech come back or hire a different tech 

esdad697

They tech came back and changed the pilot box. Now, it is working properly. He didn’t charge as when he previously changed the igniter assembly, he said, “I’m 100% sure it is the igniter assembly.”

I’m glad it is fixed.