So I have hot water baseboard heat with three zones. The basement, bedrooms and main floor. The baseboard in the master bathroom is connected to the bedroom zone. We keep the bedrooms cooler for sleeping so I want to change that baseboard to the main floor zone otherwise the bathroom is freezing. It's all 3/4" copper piping. If I were to use oxygen barrier pex for changing that baseboard, what size can I use? I know 3/4" pex with crimp fittings are restricted a lot when compared to 3/4" copper and 1" pex is closer to the same size at 3/4" copper with the fittings, but wrestling 1" pex definitely would make things harder. I don't want to starve any baseboards that are downstream, but then I know the water doesn't flow that fast. It's 180 degree water and I believe it runs about 15psi, but I don't know the gpm of the pump at the moment, but can find out if that matters. I don't want to use push fittings so I'll sweat copper to pex adapters on.