Sometimes the price of admission AIN'T worth the 'ride'. I have had good luck with the Taco's and have used two Alpha's. Both brands were in higher end situations that had multiple systems, radiant all through plate exchangers, some antifreeze protected, some not, conventional radiation, even water to air ex-changers. In any event, we were not the first guys on the job, but after 7 other firms, we got it working as the heat engineers specked, and there were no 'Bee's' or Alpha's when these places were built. Re-piping and the Bee's made the system work VERY well and made for a happy homeowner.
EACH APPLICATION IS DIFFERENT, so never assume a canned response will solve the problem. Especially when some really good folks preceded you; folks you respect a great deal.
Thinking outside the box will NOT work for everyone, and many times a simple tweak will allow you to sleep for a few more nights.....until the next 'mind-twister' comes along..
Larry, are you trying to make your system do calculus for you, too?
Close only counts in................... horseshoes and hand grenades.