Plumbing options for new bathroom in attic rooms

[oscarthecat91]

I am planning a re-model of my loft conversion which currently contains two bedrooms to incorporate a new shower room as well. Would welcome some advice on the best plumbing options:

- There is one existing bathroom which is currently served by a 10.5kw Triton Electric Shower (already installed when I bought the house). I have a Worcester Greenstar 8000 Life 35kw combi boiler in place (installed 1 year ago, replacing a 21 year old combi) with a stated flow rate of 12.5ltr per minute. I believe the water pressure is good. Would this be sufficient to serve a Thermostatic mixer shower in the new attic shower room?
- In future I will be remodelling the main bathroom and may get rid of the electric shower if the boiler is up to running both showers? If not the electric shower can be kept in situ in the main bathroom with the thermo mixer in the attic
- The new shower room will be built directly over the existing bathroom. Hopefully it won't be too challenging to extend the hot and cold plumbing up. The existing cast iron soil pipe extends as far as the 1st floor bathroom, I assume this can be extended with PVC and some sort of joining kit to extend to the loft?
- There are radiators already in the attic which will need moving and an additional towel radiator for the bathroom installed. This will mean the boiler will be running 9 rads which I think should be ok?

Thanks

 

[muggles]

Yes, your boiler would serve the new shower in the attic, although if the new room is a long way from the boiler you may wish to consider the amount of time it's going to take for the water to get hot there. Would you be better off moving the electric shower to the attic, and having the mixer shower in the existing bathroom? I'd advise hanging on to the electric shower either way.

You probably can extend your stack, but speak to your Building Control Officer. The work you're proposing is notifiable to BC so it's best to get them involved at an early stage. Your boiler should be capable of running about 30 radiators, 9 will be no trouble

 

[Madrab]

As suggested, it would be recommended to keep the electric shower in the bathroom that will be used the least. Your boiler would struggle to run 2 mains showers at once, it's just the nature of combi's.

 

[oscarthecat91]

Thanks both for the reply. I think I will follow your advice and relocate the electric shower to the attic shower room and have a thermostatic mixer installed in the main bathroom.

In terms of the 10mm cable for the electric shower, this already runs up to the attic floor for the pull cord switch on the first floor bathroom ceiling. Can this cable simple be joined/extended in the attic floor? It’ll be a disruptive job to renew the cable all the way back to the consumer unit.

 

[muggles]

Usually it can, yes. It'll need to be joined either using an approved maintenance-free junction box, or in a box which can be accessed for future maintenance. The only thing which might make a difference is the length of run, but you can usually go quite a long way in 10mm even with a 10.5kW shower.