Weil-Mclain ultra series 2

[colin hawkins]

i have a Weil-Mclain ultra series 2. It has the cast aluminum heat exchanger. It was installed when my home was built 12yrs ago. I have infloor hydronic heat. The boiler has been a fair amount of trouble. The fan was replaced under warranty 3yrs into its life. A tune up kit and cleaning of the heat exchanger was done last year. And every year...About 3 weeks ago I was giving me the fail too Ighnite code, so I replaced the Ighniter. Runs for a while a d says same error code. The aluminum heat exchanger gets a lot of black gritty stuff in water condensation drain tube but when I was serviced a ton more came out, seems odd that that much stuff would be junking up the guts of the boiler. Can a aftermarket stainless exchanger be put in place or not worth it. 3 weeks of no heat. A service tech has also tried increasing the amount of gas let in on the valve. No luck. Do I need a new boiler?

 

[Dana]

Is the radiant floor done with EPDM tubing (Onix, et al) or is it PEX?

Aluminum heat exchangers are more sensitive to system materials than stainless, EPDM has a long and lousy history of "mysterious black goo" clogging water tube heat exchangers (of any material).

At 12 years an aluminum modulating condensing boiler that's been having problems might very well be nearing end of life, but it's hard to say with certainty. And that very uncertainty might be reason enough to replace it.

If you're going to replace it, a right sized boiler with a stainless fire-tube heat exchanger is going to be a better bet going forward. Since you have a heating history on the place, run this math to measure the design heat load using the boiler as the measuring instrument. With radiant floor systems there is rarely a point to upsizing from the 99% heat load by the ASHRAE 1.4x recommendation, but most homes in AK can be heated with any 80,000 BTU/hr-in mod-con boiler with a 10:1 turn down ratio, of which there are several. But before picking one that might be better supported locally, first come up with the load numbers.