bath moved downstairs 22mm pipe right up to cylinder ?

[runforestrun]

I am putting in new watertank and feed/expansion tank for an indirect vented system in loft. Making tiny bathroom upstairs into ensuite removing 4ft bath and replacing with electric shower .

In my bathroom DOWNSTAIRS i am going to remove present shower and install a new bath 30ft or so away from hot water cylinder upstairs presently i have 15mm hot cold pipes running downstairs.

Question is MUST I RUN 22MM HOT WATER PIPE ALL THE WAY FROM CYLINDER to new bath ripping up untold floorboards not to mention the cost. 1st time on here so please be kind!

Obviously dont have combi and dont think i ever will.

 

[Bahco]

I would leave it at 15 mm if it was too much trouble.

Your bath will take longer to fill but you can always change pipework if you have to.

Should be plenty of pressure if the bath is going downstairs anyway.

 

[runforestrun]

thanks 4 reply ive just got in . The thing is the pressure downstairs really ain't that good in the sink already down there. My wife will say its alright until she tries to have a bath which takes 20mins to fill ! while im ripping up boards i think i will do it with 22mm but does that have to stretch all the way to the bath from cylinder my guess is it will . Also can i tee off 15mm pipe on route to bath, for upstairs sink and downstairs sink. any ideas please..

 

[ajs heating]

15mm not any good for gravity water 22mm all the way to the taps.
15mm tee up to the basin.
as all gravity systems bigger the bore the better

 

[runforestrun]

Thanks ajs i appreciate your help after a long day! My bath downstairs is in the extension on the back of the house , the 22mm pipe will run straight into the loft space of extension and not go downstairs to kitchen sink 1st. Before the pipe goes off to the loft space to go to my bath i NEED TO TAKE 2 RUNS off the 22mm pipe 1 for the sink in upstairs bathroom (approx 6 foot) and 1 for kitchen sink downstairs (approx 20ft) will this AFFECT THE FLOW/ PRESSURE for the bath downstairs ? :win[/b]

 

[JohnD]

if you do plumb it in 15mm, lay in a good stock of books to read while you wait for the bath to fill

If your branch is just for a basin it will not matter, but if you mean for the shower, a dedicated supply is better. Anyway, your cylinder will run out of hot water if you try to use shower and bath together.

On a gravity system the shorter and more direct the pipes are the better the flow will be. Even Tees and elbows slow it a bit.

 

[runforestrun]

thanks john you know your stuff i was editing my post while you replied WOW thats efficent. I am being more specific now the 22 pipe runs straight from cylinder to extension at back through its loftspace it cant run to kitchen sink downstairs 1st and don't really want to run it round the ensuite for wall hung basin i know you said it will affect pressure abit but can i branch off 22mm pipe twice before goes into the extension through loft for bath downstairs ?, 20ft for kitchen sink 6ft for sink in ensuite upstairs with say 15mm pipe? or would that affect pressure too much i realise it will a bit when sinks are used but you only use bath once a day i hope ! :By the way will not branch for electric shower that will come off mains IM LEARNING SLOWLY !

 

[JohnD]

you can get tables of flow loss per metre and per fitting for different pipe sizes, I am not a plumber but one of the old hands will know off the top of his head.

the run to sink sounds quite long so flow will not be very strong. but a bigger pipe will take longer to run hot

remember to use foam lagging on the pipes, with the thick BS stuff in unheated voids like loft and underfloor.

 

[runforestrun]

Nothings ever straightforward! Thks john once more. Flow loss per metre , makes sense. Anyone know floe loss per metre for a 9metre branch using 15mm off 22mm hot water pipe? Would it make too much difference to my bath ?I want to get stuck in cos im off now for weekend!
But want to plan and save alot of headaches

 

[JohnD]

hee hee! Too difficult for me!

http://www.aquatext.com/tables/frict-wat.htm
try the spreadsheet and compare figs with 15mm then recalculate with 22mm if you like

 

[runforestrun]

I dont think i can do the calcs either ! Does any one think branching off 22mm hot water pipe 20ft with 15mm for kitchen sink will affect hot water flow / pressure water to bath on along distance run to down stairs bath?