I have a TACO 5002 miximg valve not holding temp. 1 year of operation in a radiant system. Any other of you guys had troubles? If I adjust it all the way in and back it out it will act ok for a while. I see that they have a replacement cartridge for it but I did not have room to isolate it with 3 more valves in my cramped space, so that means a drain down to service it. Maybe I'll just have to fool with it until warmer temps?