10mm feed for small wc room

[iamlee2002]

Hi all, just in the middle of creating a small wc in our bedroom. My question is can i run a 10mm pex pipe feed from our bathroom hot water pipe to the upstairs toilet basin? Reason im asking is because its about a 12 meter run of pipe was just thinking the boiler would heat up less water etc. ive already put in 15mm pipe work under the floor boards upto the basin. Just wondering if it would work or would i be best to keep 15mm throughout?

thanks in advance

*Edit: using a combi boiler

 

[mogget]

This ones going to depend on your mains pressure, personally if it were above about 3bar then would have no worries running 10mm to basins.

But check the pipe can take the pressure (hot) in the manufacturers specs.