I have PEX without O2 barrier in the cement slab (zone1) and baseboards (zone2). Its a 2 zone closed heating system. Baxi Luna is the heat source, mixing valve to drop temp for radiant, two Taco IFC cast iron pums; each pump in each of the zones. System was installed this spring. This will be the first heating season. Radiant water temp will be about 100 deg. baseboard 170 deg.
I did not realize at the time when plumber finished/was paid that the cast iron pumps are not optimal for the no-O2-barrier PEX system (He was a young kid, did not know any better?).

The question is: will/how soon the pumps will fail, should I run system as is until pumps fail or install bronze or stainless steel pumps now.

What should I do? Thanks!

System is in vacation home, cold climate, freezing is a problem.