zone valves

jacsul

I have a simple radiant system in my home. When the outside temp gets above 30 degs the house starts to overheat. I've turned down the water temp. to 90 degs to help with the problem, but it still gets hot in here. Would a zone valve create a flow problem with the circ. pump on a radiant system. My system is 1 zone with a 50 gal water heater closed loop