As for the bypass system; some plastic valves used in a few bypass kits can be prone to early demise due to the effects of cold and heat. I’ve not heard of any problems with brass valves in such applications, but the cheaper, plastic ones worry me. It’s plausible that the cold and heat extremes have damaged the seals inside the valves thereby rendering them inoperable. Warping or distorting of the plastic valve body may also contribute to a faulty valve. Perhaps, even, a bit of dirt or hard calcium particle migrated through the system into the valve and damaged the seal.