Hydronic Heating Zone Valve Placement

I am replacing three radiator hydronic plumbing Zone Valves. I suspect that the valves I am replacing were installed incorrectly, namely the water flow direction is the opposite as incicated on the valves. One pipe is coming from the heater to the Zone valve area where this pipe splits into three lines into the Zone valves. It seems that this pobably is the feed line. Is it possible to have been put on the return line? I am installing Honeywell V80443 E 1020 motorized valves. Does the flow direction that important? Any help would be appreciated.

John Parker