Confused about what shower system to install

[Bathroommonster]

Hello, I am new so I am not sure whether I am repeating another thread here, but here goes.
When we moved in, almost 9 years ago, we put in a new boiler (valiant eco etc plus 624). I also have a Unistor unventilated hot water storage tank. Both are installed in the attic. It's a 4 bed house. There is a tiny family bathroom, which has a thermostatic shower. When a tap gets turned on, the temperature stays alright but the flow slows a little.
We are thinking of installing another "kids bathroom" in the attic but this is were I get confused.
Which system would work for this set up? As both the boiler and new bathroom would be in the attic do I need a pump? What would you advise? Any help appreciated.

 

[ianmcd]

your unvented cylinder should handle two showers easily enough but all depends on the incoming mains flow rate, usually they are OK but you should check first

 

[simond]

You can't fit a pump to your uniSTOR, it is against water regulations.

You can fit any shower designed to work on an 'unvented' system; however I would advise you to choose one with a modest flow rate* if your water supply is a bit limp.

Be aware that the performance of both units will be compromised in terms of flow if you try and use them simultaneously. The only solution for this is to uprate the incoming water supply. This is where it can get complicated and expensive.

*somewhere between 8-14 litres per minute.

 

[Bathroommonster]

The only solution for this is to uprate the incoming water supply. This is where it can get complicated and expensive.

Hi Simon, thanks for the advice.
If I fit a "normal system" now like you advised for low pressure, can I still do the expensive upgrade at a later time or would it not be compatible then?
Also, "complicated and expensive"...tell me more, please?
Thank you

 

[dilalio]

The only solution for this is to uprate the incoming water supply. This is where it can get complicated and expensive.

Hi Simon, thanks for the advice.
If I fit a "normal system" now like you advised for low pressure, can I still do the expensive upgrade at a later time or would it not be compatible then?
Also, "complicated and expensive"...tell me more, please?
Thank you

Your hot and cold water both depend on the flow rate and pressure of your incoming water supply. Opening ANY additional outlets (hot or cold) will affect the performance of one already open, to the point where all open could result in nothing but a dribble from each!

Improving this 'incoming' flow rate can be achieved using various methods...

1. Worth checking that your existing stopcock is not restricting the flow due to not being fully open or age - replacing might improve things.

2. Replacing the main, your side of the supplier's stopcock, having checked that what they are supplying you at their side is enough to justify replacement to improve the installation. This will mean excavation outside and likely pulling up floors inside. Could mean further repiping inside too.

3. Installing a break tank/pump or accumulator...
//www.diynot.com/diy/threads/accumulator-or-break-tank.184439/