Problems troubleshooting quirky boiler

[wiadnm]

I have a Weil-McLain HE-6 Series 2 boiler (about 18 years old) that tries to ignite but sometimes go through a few cycles before turning on. Sometimes it tries to ignite and the flame immediately goes out other times it will try to cycle on and then go through the pre-purge process before lighting. I had my plumber check it out yesterday (he tested all components and they check out ok). He told me that he spoke to a friend having a similar issue and they replaced multiple components (one by one) trying to resolve the issue. After replacing many components it did not resolve the issue. My plumber mentioned that he tested the gas and it came in at 7lb/in but fell 2lb/in when the boiler cycled on. Not sure if this is a symptom or where to go after this. I told him about this board but unfortunately he did not have i-net access to post a msg so I offerred to post for him describing the problem the best I could. Any ideas I can pass along to him?

[simpleman]

If I recall that boiler at one time had issue with the pressure switch getting alot of condensate in them.

We had to install condensate traps to keep the water from entering the switch.

Hope this helps.

[millerman]

After reading your post I am curious why you have a plumber trying to diagnose this issue when you should have a technician look at it. As Simpleman states it could be the pressure switch however, it could be many things that a person trained in gas heat can fix without throwing parts at it. If you don't have a mechanical contractor you trust ask your freinds who they use and get it done right. Good luck.

[wiadnm]

I just refer to him as my plumber. He's a licensed HVAC guy. I've used him numerous times and found him to be knowledgeable, reliable and honest.