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Weil-Mclain Ultra Series 3
It's a model 105 in this case, but don't think it matters. Just a message in short - don't ignore annual maintenance/cleaning forever :-) These boilers are great. I've had a 105 for 7 years now with no issues. One thing I did? No maintenance. Problem is that most of the contractors around me get all scared about these high efficiency boilers. Then have to over charge for parts and service because they come to the house, are blind in terms of knowledge and just call the WM hot line as they work on it, then order parts, etc. I've worked on domestic oil burners (full training) as well as early version domestic gas "jet boilers" - factory trained and certified on Lennox "Hydro Pulse" way back then - remember then?
That said, my WM Ultra S3 105 started acting "unfriendly" during this last coldish spell in SE PA. Through the site glass I could see spark then ignition/flame then it would shut down after about 30 seconds or so. Repeat.
So no lockout, no ignition failure or other diagnostic errors. Running diagnostic inputs from front panel, watched flame signal during ignition/fire. Erratic and low based on WM S3 Manual page 96 flame signal chart figure 106. I figured burner, ignitor, heat exchanger should need cleaning but wanted to just get things burning. while waiting for parts.
Watching diagnostic - saw that flame signal was well below the 20 degree differential for shutdown value. AKA saw around 114 max/135 signal. There were times when it was marginal enough to hold fire and keep running. Only to have it fail again later.
I had all the parts ordered to do a full cleaning/annual at this point, but just needed to get things running.
Pulled the ignitor/sensor. Two phillips screws. Pull out slowly to not disturb the gasket as best as possible. Took some 240 wet paper and cleaned off the white oxidation from the electrodes and folded it to push between the air gap and brighten the actual arc points. Voila - fired up and running after assembly.
I'll do the heat exchanger cleaning, ignitor replacement, burner cleaning once I get the parts and the cleaning tool. As I should have done previous. But just saying - sometimes you can find the specific culprit through reading and understanding the unit and how to get into diagnostic mode. I'll be less "recalcitrant" now and set the maintenance reminders on the front panel to tell me to get my ass in gear to do routine maintenance following the manuals.
My challenge is that I don't want a contractor that is not familiar with these units wasting $$$ while they are calling hot line, then ordering parts and charging $100 for the vist and 300% over parts cost to recover the hours spent. One fellow I called who is a neighbor in the business basically told me that he would be totally unfamiliar with the "new tech" and would not have parts on board to fix anything.
If you do get a service contract on these make sure first that the contractor has full knowledge and understanding how to troubleshoot and has parts stock on hand for these. Otherwise performance will vary.
So in short "RFM" and you can get yourself out of trouble in the short run if you have some knowledge and and initiative to understand "how things work". Always use care and shut down the system before doing any work. Now how to do that or don't touch it.