Shower pipe sizes

[duffsparky]

Hi All,

I first started this post in the shower section but as I've had no replies I guess I put it in the wrong section.

I'm re-modelling our bathroom, en suite and installing a shower in our ground floor toilet/cloakroom. I've run low on money so I'm just concentrating on getting the shower into the ground floor toilet/cloakroom but eventually I'd like to have a shower in the en-suite and bathroom, both on the first floor, as well.

Ideally all the showers will be gravity fed and I'd like some advise on pipe sizes for the showers. The cold water storage tank was raised several years ago which gave a reasonable shower in the now removed en-suite.

Attached are 2 drawings showing my proposal, they show all shower pipework to be 22mm taking the feeds from the existing 22mm pipes beneath the bathroom floor. I'm wondering if my design using 22mm pipe throughout for the showers will give that much of a better performance over 15mm pipe, especially pipe drop D for the ground floor toilet/cloakroom shower. Is my design a bit overkill?

Also would it be better to take the shower feed(s) from as close to the water storage tanks as possible, maybe even changing the hot water tank draw-off outlet from 22mm to 28mm (if possible) and modifying the first section of pipework to suit, perhaps it would be better still to add an additional 22mm draw-off outlet point to both tanks tanks.

The cold old water storage tank is not directly above the hot water tank, it is about 7 metres horizontal distance away and raised up to give a water head height of about 2.4 metres to the first floor shower mixer valve positions and about 5 metres to the ground floor toilet/cloakroom shower mixer valve.

The 2 drawings are essentially the same except the second one has less written detail to make it clearer(?).

Thanks in advance.

 

[justlead1]

Hi using 22 mm will give better performance than 15 mm, although you may well need to reduce when connecting to the mixers. (the square area of 22 mm is double that of 15 mm) You will pull a bit more cold out on the dead leg, but if you get into turning on the shower before getting your kit off it should work well.

 

[duffsparky]

Hi using 22 mm will give better performance than 15 mm, although you may well need to reduce when connecting to the mixers. (the square area of 22 mm is double that of 15 mm) You will pull a bit more cold out on the dead leg, but if you get into turning on the shower before getting your kit off it should work well.

Presumeably you refer to reducing pipe sizes to connect onto mixer inlets which are 1/2" BSP with an 8mm dia port. I'll be using 22 x 22 elbow -> 22 x 15 reducer -> 15mm full bore isolator valve connected directly(?) onto the 1/2" male mixer inlets all butted up to each other.

When coupling the isolating valve to the 1/2" male inlet on the mixer I need to keep the assembly as short as possible and I doubt if i'll have enough room to use a 15mm x 1/2" female adapter, all the ones I've seen are too long and all the 15 x 1/2" isolator valves seem to be small bore. Therefore, I wondered about joining the isolator to the mixer inlet using a 1/2" x 1/2" female/female socket and screwing the 2 together such that the mating faces don't quite touch so that there is enough of a gap between them to fit an "O" ring or similar that is supported by a short stub of 15mm tube fitted in the normal place. Any thoughts?

 

[justlead1]

hi. Complacated to follow. Reduce down say 300 mm from mixer. If it make life easier. It will not have a big effect on the supply.

 

[tackleburger]

You will be better with 22mm from the tank and cylinder to the upstairs shower. The downstais shower will be fine in 15mm with that kind of head. It may be an idea to increase feed to cylinder to 28mm and a 28mm take off from the cylinder until both showers are tee'd off.

 

[duffsparky]

hi. Complacated to follow. Reduce down say 300 mm from mixer. If it make life easier. It will not have a big effect on the supply.

Apologies for the complication, what I was trying to explain (but not very well) is connecting the 15mm isolating valve to the 1/2" male mixer inlet by removing the isovalve compression nut & olive and replacing it with a 1/2" x 1/2" female/female socket like in the bottom left picture +4. The "O" ring would sit in the middle of the socket to form the seal.


1 +2+3
+4+5+6



The mixer inlet and outlet are off-set, unlike in the righthand picture, and fit through a wall mounting plate.

Alternatively I found this 1/2" female x 15mm O/D tail by JG (Speedfit) but they are quite expensive at £4 each

 

[PlumbBobBob]

isolators don't need to be that close to the shower, will be easier if they are not. you are being unnessarily overcomplicated. you just need to bring the pipes from where they are teed into the system up or down the wall whichever way you are going, then bring them into the wall plate and then into the shower. as said only need to isolate where pipes tee off feeds giving yourself easy access to the isos.

 

[duffsparky]

Hi Steve,

Thanks for the reply.

I've just added a bit to my previous post.
If I connect to the existing supply pipes it will have to be done beneath the floor where access at a later date will be difficult unless I put access boxes/plates in the walls. I'm aware the isovalves do not need to be as close as I've suggested, but it would be very convenient as they will be out of sight below a corner shelf to be fitted on top of the corner wall bracket supporting the mixer valve, see photo

The picture shows the right hand assembly sat on top of the corner bracket, when finished it and the left hand one will be beneath making access to isovalve very easy.

Left hand pipe in picture is not in final position, it should be inside the chase to the left of it.