I currently have an electric shower with cold water feed and its own "isolator" with a string pull outside the shower.

Looking to have it replaced (by a professional, so I'm asking more out of curiosity and to understand the process rather than to do it myself) with a shower fed from the hot and cold water tanks.

The setup is a hot water cylinder, cold water tank that feeds the current shower and the hot water cylinder. These tanks are on the floor upstairs from the bathroom.

Been told that to have a mixer shower we need one with a pump due to water pressure (lack of) between the tank and the shower.

I am now looking at "digital" showers with the temperature controller where you can set profiles, schedules etc.

I would like to know whether there will be significant electrical work involved in replacing this electric shower with the proposed digital shower.

  • I'm assuming the "controller" for the shower still requires the electrical connection? (Mains voltage - this is in the UK so 240V)
  • as such, do I still need the "isolator" string pull?
  • can anyone give an easy to understand explanation of how the "digital" shower does its thing?
  • if the current electrical connection for the shower is redundant, does it need to be "closed off" in some way?

As said above I am getting a professional involved not intending to do it myself, but would like to be somewhat 'in the know' when I speak to them!

NB: there is already hot and cold water to the bathroom for the sink and existing bath (which has the shower over it and will be replaced by just a shower cubicle). The cold water taps come off the mains feed (1 floor below) rather than the cold tank.

  • Have you gotten cost estimates? Are the hot and cold supply pipes pressurized for the sink and the bath (tub?)? What is the source of the hot water, i.e., what kind of water heater--tank or tankless? So you have a hot water supply to the hot valve on the tub, but the shower head above is an electric shower fed by cold water? Sep 6, 2019 at 17:30
  • @JimStewart I am at the stage of looking to get cost estimates, but trying to understand whether what I am asking for is possible/feasible (I guess pretty much anything is possible given enough money! :) ) and to have some info already when I talk to professionals. The hot water source is a (140 litre, I think) "cylinder" (tank) which is heated on a schedule by the boiler/furnace. Yes the bath/tub has a hot water supply, but the electric shower is cold water feed and has its own heating element etc inside itself. Sep 6, 2019 at 17:34
  • So you wish to use the existing hot water supply to feed the new shower? Does the existing tank water heater heat the water to 60 C? Does the hot water come out of the hot taps of the lavatory and the tub very hot? Sep 6, 2019 at 18:44
  • @Jim Yes, I want to use the existing HW supply to feed the new shower. I haven't tested the exact temperature but it does come out subjectively very hot (and is adjustable by a thermostat, which is set somewhere in the middle at the moment). If I run the hot tap by itself (without any cold mixed in) it is uncomfortably hot to put my hand in. Sep 6, 2019 at 18:53
  • Don't heat up and cool down stored water. Keep it at 60C or don't heat it at all. That's to avoid bacterial growth that can kill you (legionella). Sep 11, 2020 at 18:31

2 Answers 2


These may be the type of valve for your application thermostatic mixing valves for shower. They come with a diverter for switching between tub and shower, and some may be without a diverter. Since you already have valves on the tub it is not clear to me which kind would be best for your situation.

EDIT I believe that you would be required to remove the wires that powered the electric shower head.


A digitally controlled electric water heater may be the cheapest option, the same mains electrical feed would be used. When there is water flow the heater adjusts the flow to maintain a preset temperature. I have a small 30 amp 240v electric that works this way we need a fair flow so we set it to the minimum temp we want to bathe our show horses ( it takes a lot of water to wash a horse).

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