Can I have an electric shower and toilet on same feed from CWS tank?

[Ch_152]

Current electric shower and toilet are fed from mains supply. Pressure is terrible (have had plumbers and Thames Water round - no dice), so I've been advised I could try an electric shower with built-in pump that runs from the CWS instead (example).

However, I'm not able to get a new pipe into the bathroom. So if I go for it, both the shower and the toilet would need to be fed from the CWS. Bathroom and CWS cupboards are on the same floor (CWS at high level in spare room cupboard).

Is this likely to present any issues? Some thoughts I had:

1) Would there be an issue filling the toilet cistern from the CWS?

2) Would there be issues if the toilet is flushed at the same time as the shower is being run?

3) The two existing outlets from the CWS run to a salamander pump (for cold water), or to the vented hot water cylinder. Is taking the feed off one of those for the shower a bad idea (i.e will I need another hole in the CWS for a separate outlet to the shower/toilet)?


I do not plan on doing this myself, but working out whether it's feasible before getting a plumber in to take a look!


Thanks


Chris

 

[Elsa TLC]

Hello Chris

Electric showers are designed to work on mains pressure.

You could use a pump , and if so that could supply a WC.
However I wouldn't recommend it.

 

[Madrab]

I could try an electric shower with built-in pump that runs from the CWS instead

Yes, no reason not to - the problem like any electric shower is the fact that it's heated by an electric element. It can only heat the water so fast, therefore it is restricted to how much power it uses as against how cold the water is in relation to how hot the person wants the shower to be.

To get the best experience get a 10.8Kw and run it off a fat 10mm cable @ 50A but you need to ensure the consumer unit can handle that too, that and the electric installation can cost as much if not more than the shower itself.

These do allow you to use stored cold water as against using the mains. They need a min supply per min too - usually around ~ 10L/Min. They can both be run from the same CWSC supply pipe yes, just try and avoid using the toilet at the same time.

 

[Ch_152]

Thanks for the replies. Unfortunately existing electric (without pump) shower is only on a 6mm cable so I can’t go up to 10.8kw (and the cable has been sealed in behind the tiles by some wayward mortar so there’s no changing it).

I currently only get ~2.5 or so l/m from the electric shower on the mains, so I think the one with built in pump should at least be an upgrade on that until I can afford to do a full bathroom refurb and run a mixer shower with external pump.


Anyway sounds like it’s possible to run both the shower with built in pump and toilet cistern off the same supply into the bathroom.

Tbh it would be very unlikely that they’d ever be in use at the same time as I live alone…

 

[Elsa TLC]

Thanks for the replies. Unfortunately existing electric (without pump) shower is only on a 6mm cable so I can’t go up to 10.8kw (and the cable has been sealed in behind the tiles by some wayward mortar so there’s no changing it).

I currently only get ~2.5 or so l/m from the electric shower on the mains, so I think the one with built in pump should at least be an upgrade on that until I can afford to do a full bathroom refurb and run a mixer shower with external pump.


Anyway sounds like it’s possible to run both the shower with built in pump and toilet cistern off the same supply into the bathroom.

Tbh it would be very unlikely that they’d ever be in use at the same time as I live alone…

Are you thinking of a power shower and nit an electric shower?

 

[Ch_152]

Are you thinking of a power shower and nit an electric shower?

I linked one in my oroginal post, but here is the unit I'm looking at:

Triton T80SR


It's an electric shower with a built-in pump.

 

[Elsa TLC]

I linked one in my oroginal post, but here is the unit I'm looking at:

Triton T80SR


It's an electric shower with a built-in pump.

I honestly never knew such a shower existed.

 

[Ch_152]

I honestly never knew such a shower existed.

Fairly uncommon I think. Mira also do one: Mira Elite SE 10.8

 

[Ch_152]

So reading the requirements for the above, it requires 8cm of head (8cm between bottom of CWS and top of shower unit).

Unfortunately I do not have that, so that’s that idea scuppered!

 

[Madrab]

Fairly uncommon I think.

They were until about 5 odd years ago when they started to become more available

it requires 8cm of head

It does yes - it needs a very minimal gravity flow.

How is your HW delivered at the moment?

 

[polesapart]

Nomenclature; 7.5-10.8kw on mains water = electric shower

Intergral pump on gravity feeds with weedy cable = power shower

 

[Ch_152]

It does yes - it needs a very minimal gravity flow.

How is your HW delivered at the moment?

Makes sense.

At the moment hot and cold water to the bathroom taps and shower over bath are both gravity fed (vented cylinder for HW), via a salamander pump.

Ideally I would just get a mixer shower run from this, but would require some significant building works in the bathroom.

 

[Ch_152]

Nomenclature; 7.5-10.8kw on mains water = electric shower

Intergral pump on gravity feeds with weedy cable = power shower

And what I propose is neither of those things.

It heats the water (has a not weedy cable) and has a built-in pump fed from the CWS.

 

[Johntheo5]

So reading the requirements for the above, it requires 8cm of head (8cm between bottom of CWS and top of shower unit).

Unfortunately I do not have that, so that’s that idea scuppered!

8cm is only 3 inches, also I don't know why the tank bottom is allways quoted, practically speaking, its from the water level in the CWS cistern that should determine the minimum requirement so that might meet your requirements?.

A few other points, the T80SR (SR stands for silent running) is called the T90SR in this neck of the woods, I have a T80 which is a mains supplied shower so ensure that you are looking for a integrally pumped shower.
6MM2 cable will supply a 9.0kw shower so assuming a "average" showering temperature requirement of 40C, a 9.0kw shower will supply a flowrate of 3.8LPM from cold water supply of 6C in the very debths of winter, a more realistic cold mains of 10C will give result in a flowrate of 4.3LMM at 40C and at 15C will result in 5.2LPM.

A well known shower installer (> 1000 showers/annum) a contributor to our Boards.ie website has a very very low opinion of the pumped Mira Quiet (called, I think here), he said that after 3 attempts to re engineer a simple item like a water elbow that they still fail and start leaking and very frequently the pump/motor fails, he said he has rarely if ever had to replace the pump/motor in the Triton T90SR.

 

[Madrab]

Nomenclature; 7.5-10.8kw on mains water = electric shower

Intergral pump on gravity feeds with weedy cable = power shower

And a newer type - a pumped electric shower - 7.5kw > 10.8kw electric shower with integrated cold water pump so just like an electric shower but it has a small pump for the cold water supply.

Mira Elite SE 9.8kW Pumped Electric Shower | Showers Direct

Mira Electric Shower | Powerful Performance ✓ | 100% Silent Showering ✓ | Easy to Clean Filter ✓ | 2 Years Warranty ✓ | FREE Delivery | Buy Now

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