Welcome! Here are the website rules, as well as some tips for using this forum.
Adding underfloor radiant
I currently have hot water baseboard heat using a Navien boiler (having a circulator) feeding 4 relatively short zones in our one floor + basement house just built. The four zones are fed by 3/4" pex and another circulator and are : 1. Bed1 and basement 2. Bed2 and Bath 3: Living Room 4;DHW. I am planning to add underfloor radiant using the basement ceiling. For this I will use 1/2" pex. I would like to add the 1/2" pex to one of the four existing loops (up to 300') and I am wondering if such a plan would be manageable by the circulators or will I need another circulator and use a completely separate loop for the underfloor.