Zone valves are in supply or return of hot a water boiler?
by pshab Question by John: Zone valves are in supply or return of hot a water boiler? Multiple zone system. No one seems to have a factual answer WHY. Best answer: Answer by Jim MIt can be done both ways but I prefer to put them on the return side which keeps the supply side hot when even one zone calls for heat so when a second calls for heat the supply side is already hot. Give your answer to this question below!