McCann Big Mac Carbonator: Backflow Valves Keep Blowing Out - Beer, Wine, Mead, & Cider Brewing Discussion Community.

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Oct 15, 2011
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I have built a homemade (seltzer) water machine with a small corny keg and the Mc Cann tank in a small fridge under the house (directly under the Kitchen). The Mc Cann motor sits on top of the fridge.

After about a year the Backflow preventer on a rebuilt Big Mac blew and c02 was pushing back up the line. So I went out and bought a new Backflow valve. 1 year later and that brand new one blew out again (no c02 pushing up the line). So again I bought a new valve and 1 month later Ive got water spitting out the backflow non stop. C02 is not pushing back into the corny so the stainless steel catch is doing its job (thankfully).

So now I am wondering if I am doing something wrong and I have a few questions:

Is there any other issue that could cause water to constantly spit out of the Backflow valve?

Could there be some other factor that is causing my Backflow valves to blow out (I am on my third in 2 years)?

I very much appreciate any and all enlightenment!
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