The best boiler to replace Weil Mclain Ultra 230 (Series 2 circa 2006)

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Hello, everyone.
I am seeking advice/recommendations on the boiler replacement.

We never had a boiler system at home, so I do not have any first-hand experience with any boiler brands, and your experience and input would be greatly appreciated.

Current Boiler setup:
2 X Weil Mclain Ultra Series 230 (230 MBH, 94.1% Efficiency), Series 2 from 2006 to connect to the following:
- Hot water storage tank (also WM)
- 3 x Hydronic Air handlers
- 13 zone in floor heating

We recently moved into a new house, and this is our first winter and would like to deal with these before it gets too cold.
The biggest issue that I discovered was a small pinhole on the heat exchanger (on the flue condensate part) in one of the boilers, and when I opened it to do annual maintenance, it is clear to me that the previous owner did not take care of these units.

For now, I patched the hole to stop the potential leak with a JB weld high-heat putty, and I want to resolve the problems.

I read that these heat exchangers are made out of aluminum and this is a known problem to develop problems caused by acidic condensate liquid.

Do you have any suggestions for the best replacement boiler idea to replace these units? And the rough cost of the job to replace 2 boilers?

Also, I notice that the hot water tank is as old as the system and thought that it would be better to have the combi boiler units, so I can get rid of the hot water tank. Is it an idea that is worth a venture?

Thank you in advance for your time and expertise.


The wife is still training me.
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Orlando, Florida
I never had to deal with a boiler but having owned five homes in the last 43 years, deal with a local company that has been around for a while and most important, they can support the product on service and warranty because they are an authorized distributor of the manufacture. A company like this after many years knows what boilers are more reliable since they do not want home service calls for problems. Another good sign is the company or rep will do a heat load calculation so the you get the right size unit. Replace the water tank because as it ages it more likely it can leak and cause more problems.

John Gayewski

In the Trades
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I would only hire someone who does a heat load calc. Also no one is going to be able to tell you a "good price" the range would be between 10k and 30k.


Well-Known Member
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Peace valley missouri
All condensing boilers get their 95% efficiency by condensing return water temp has to be 140° or below above efficiency goes to 87%. Water temp for air handlers run 160° supply or more. Contractor is more important than brand. Combi heaters need heating load and dhw max flow rate, lowest incoming water temp and if gas service availability. Do some research on combi systems and some of their problems. Pumps if there getting replaced go with a ecm their more efficient.
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