gravity fed thermostatic shower pipes

[cambio]

hi, just updating bathroom and fitting a thermo bar shower to replace a tap shower feed. Old tap feed also only had tank cold and mains hot so was a nightmare to balance out and not get backfeed and cold shower.
Anyway, hot water from vented cylinder is 22mm, had fitted a new feed from the cw tank in the loft in 15mm. Shower flow is not great (7.5 l/ min) so would it be worth changing cold feed pipe to 22mm?
cw tank is about 3m above shower head, mixer is good for 0.2-5 bar. Planning to get a combi in the longer term which would largely resolve pressure issues but if 22mm is worth it i'll do it now.
thanks in advance!

 

[Dan Robinson]

Depends what your definition of "longer term" is really.

check what restrictors you left in the shower valve too.

 

[cambio]

Long term hopefully 6 months. No restrictors in mixer, nrv in hot feed only, full bore valves on both 15mm feeds bar. Tempted to replace bathroom pipe in 22 leaving the rest in 15 see if it changes, changing a few metres of 15 might show if its worth it?

 

[kvsalamander]

Just out of curiosity,

Without being seen to be advertising have you considered a pump? Obviously may not prove worthwhile if you are fitting a combi soon but its just another option for you.

regards

ken

 

[cambio]

thanks all
have replaced bathroom section of 15 for 22, few hours work (1 forward 2 back!) so will see how it goes with shorter section of 15 from loft tank to that. Not massively keen on pumps tbh as the ones i have seen/ used in the past are noisy. Things have probably moved on since then but it would be a bit of an awkward install pipe wise, plus i would probably need a bigger cw tank. probably as easy to fit a new boiler