Repiping Ergomax buffer tank

Dave_61

Hey Guys,
Here is a picture of the piping near our Ergomax.
The upper horizontal 2" pipe is the outflow from boiler to Ergomax. You can see flowswitch as well as swingcheck valve. It then travels vertically behind Ergomax and comes toward foreground before entering tank.
The lower 2" horizontal pipe is the boiler return pipe with supply header on the left tee and then return header on the right tee.
The supply header travels up under expansion tank before making 90 degree bend and then zig zags aroung bypass (vertical pipe that has circuitsetter valve in it). The bypass goes between supply from boiler and return to boiler. Currently, the circuitsetter is off (no fluid through bypass).
The way it is currently set up, the boiler pump must run at all times when any zone pump is running or water shortcircuits between supply/return headers. All supply pumps are on the supply header and each zone pump has a flochek valve on the outflow side. There are no checkvalves on the return header.
In the second picture, you can see the supply header curving behind the bypass pipe on the left of the picture before going up to the individual zone pumps.
We want to repipe the system by moving the return header to the top of the tank so that the boiler circ will only need to run when the tank calls for heat from the boiler.
On thing I was wondering is when we do the repiping, could we just move the return header to the top of the tank and leave the supply header attached to the tee where it is (max of about 5 feet from tank inlet)?
Also, I would like to keep the bypass in case we ever have an issue with colder return temps.
Where would be the best place to tee the return header into the 1.5" pipe on the top of the tank?
Do we need any other checkvalves in order to prevent gravity flow, or should we wait and see once the repiping is done if we have an issue?
Thanks.
Dave