Flow / return pipe layout - is this sensible?

Hello folks
I've moved into a property last month and started to note things that may need looking at. Some of the radiators on the ground floor aren't getting very hot, I've had a few passes of balancing to no avail,

In light of the above, I took a look down in the subfloor yesterday to take note of the flow and returns feeding the radiators on the ground floor. And jotted down a little diagram, does this seem like a sensible way of laying the pipes out?

Essentially its as so :- For the first meter from the boiler, flow return each are at 28mm then each split into 2 lots of 22mm runs. One run powering the radiators at the rear of the property, and the other powering the radiators at the front. From the 22mm runs, they go down to 15mm to the rads,

Diagram below

Could be the pump is getting weak try turning all the upstairs off does some of the downstairs work ?

ShaunCorbs said:

Could be the pump is getting weak try turning all the upstairs off does some of the downstairs work ?

Click to expand...

I rang the boiler manufacture over the weekend, it's only 6months old this boiler so doubt its the pump so soon?
It only powers the radiators the ground floor this one.

Does the loop/s on the diagram look sensible? Im hoping to not have to rework flow and return pipes ideally.

Pipework looks fine maybe try balancing the rads ?