Gravity flow to \"off\" zones

Chuck_30

Heres the set up. 4 apts and 1 indirect W/H. Zoned with pumps on the return. Flow checks on the supply. Problem is complaints of too much heat through off zones. Their are 7 bldgs that each have this set-up and complaints are spread out through the complex.Is the problem defective flow checks and will changing them solve this or is the problem deeper? Will a flow check on the supply and return solve this? Should the pumps be pumping away from the boiler,if so,is a flow check on suppy and return needed? As these are rental units,budget is always a concern. Thanks for any help you can provide. Peace and Hugs,Chuck