Opinions on repiping

[johnny2007]

In the process of repiping the water pipes as the ceiling has been removed on ground floor for renovation.
So, background is this:
Combi boiler is on ground floor.
Hot and cold run from boiler to first floor to feed the bathroom (thermostatic shower, basin and toilet).
From there they run a floor up to the loft conversion to feed another bathroom, exactly the same as the other bathroom.
All pipes are 15mm.
Now, everything works fine but I was thinking:
Is it worth running 22mm pipes from the boiler to first floor to get better flow?
Or is it pointless?
And if it's worth, should I do that on both hot and cold or only hot? (Cold comes directly from main)
Thanks

 

[CBW]

If the inlet and outlet of the combi is 15mm you have your answer. It would lose heat if it was bigger when not suppose to be.

 

[johnny2007]

If the inlet and outlet of the combi is 15mm you have your answer. It would lose heat if it was bigger when not suppose to be.

Are you referring to water or heating?
I was talking about water, hot and cold.

 

[CBW]

I know you were and I’m referring to water. If you increase the pipe size bigger than the outlet size, then the boiler won’t be capable of heating it correctly.

 

[johnny2007]

I’m referring to water. If you increase the pipe size bigger than the outlet size, then the boiler won’t be capable of heating it correctly.

Ok, thank you.
I'll leave it as it is then.