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Single wall heat exchangers
In 2015 Minnesota changed their code to allow single wall heat exchangers for DHW in boiler systems. There are some stipulations though such as a 30psi or lower relief valve on the boiler, the heat transfer medium should be potable water _or_ contain a fluid that has a toxicity class or rating of 1 according to some book published in 1984.
Apparently sentinel x100 meets this requirement BUT a local inspector is saying that no single wall heat exchangers can be used unless everything on the boiler side is rated for potable water. Pumps, 100 year old radiators, etc.
Also, you need some warning stickers.
IMO the UPC code is relying on the difference in pressure of the relief valves to prevent dangerous cross contamination. Because even if you meet the ridiculous standards of everything on the boiler side being rated for potable eventually the water you put in the boiler will become non potable after some time. I don't foresee anyone doing a daily flush of their boiler system to maintain potable water status.
Any thoughts? Help? lol. I'd like to be able to install combis or indirects if necessary.