Repositioning Radiators and Upgrading 15mm to 22mm

[Ben-Ja-Min]

I'm planning on relocating the pipes for radiators 1 & 2 to make way for a steel beam. Radiators 1 & 2 will branch off the main flow and return between radiators 3 & 4. I noticed the flow & return leave the boiler in 22mm copper and steps down to 15mm copper before the first radiator, this then feeds 6 radiators (22500 BTUs).

While relocating the pipes would it be worth upgrading the main flow & return from 15mm to 22mm? I would do this for Rad 1,2 & 3 and leave rads 4,5&6 in 15mm. I believe 15mm copper is capable of around 14000 BTUs and rads 4,5,&6 would be 12100 BTUs. Am I right to think if I did this, I would benefit from faster heat-up times and slightly lower flow temperatures?

 

[fixitflav]

While relocating the pipes would it be worth upgrading the main flow & return from 15mm to 22mm?

I would think so, while you're at it. It's usual to have 22mm for the main flow and return, branching off in 15mm to each rad.

Am I right to think if I did this, I would benefit from faster heat-up times and slightly lower flow temperatures?

Probably, but I doubt whether you'd notice.