Replacing an electric shower?

Our upstairs ensuite electric shower died a few days ago and needs replacing, which appears an easy enough job apart from I can't figure how to stop water flowing from the inlet pipe when I disconnect the old shower. There isn't an isolating valve in the water pipe and turning off the stopcock under the kitchen sink doesn't stop the flow of water to the shower. So if I remove the old shower I'm going to have water flowing freely from the copper pipe which I presume is connected directly to the mains.

However I've noticed that some showers can be gravity fed from the cold water storage tank in the attic, I presume i can check this by closing the stopcock under in the kitchen (does this turn off all mains water?), and then empty the tank by running the cold taps in the bathroom. If the shower is fed from here then the flow should stop. However will this effect our typical gas fired central heating at all?

Or do I just remove the shower and try and fit an isolating valve onto the flowing pipe?

Advice much appreciated!

It's more than likely tank-fed, as mains is not recommended on most domestic models. Your central heating is more than likely supplied from it's own closed water circuit, so I would not worry about that for short term. Ensure that any electrical immersion is isolated if you are draining water from system.

On a last point, you may need to ensure that your shower supply from water tank is not the lowest outlet from water tank. That is so that when you go to remove shower you don't get another 20 litres of water (at least be prepared to). I'm presuming that you can't drain the shower line on cold if knackered?

You will have to find out if the shower is feed from the tank (chances are in Ireland) or from the mains. No way to tell from here what the stopcock under the sink turns off. Turn it off and run the taps etc. If you have the correct tool it is easy to turn off the water into the house on the road.

Showers designed to be feed from tanks have a boster pump in them. Showers designed to be feed from the mains (high pressure, not Irish pressure!) don't have one, but can still be used with a boster pump.

Towger

Thanks guys, much appreciated, the current shower is a Triton T90 with a small pump inside the shower casing itself. We have a separate "power shower" with a much larger pump that draws water from the hot water cylinder and cold storage tank, nothing to do with the broken "instant electric shower"

SineWave said:

Ensure that any electrical immersion is isolated if you are draining water from system.

On a last point, you may need to ensure that your shower supply from water tank is not the lowest outlet from water tank. That is so that when you go to remove shower you don't get another 20 litres of water (at least be prepared to). I'm presuming that you can't drain the shower line on cold if knackered?

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Not sure i understand this bit Sinewave, we have a large hot water cylinder, part of the heating system, with an immersion switch - we never use it, use the heating instead - do you mean to to just make sure that the immersion switch isn't on or to actually stop the tank draining?

I can drain the shower line even with the broken shower, albeit slowly, I presume I have a stopcock in the attic to stop the cold storage tank filling, the one under the kitchen sink turns the kitchen cold tap off, is it likely to do the cold tank also?

Finally, is it OK to replace a 8.5kW shower with a 10.8kW one, theres lots of mention in the fitting instructions about ensuring that the wiring is capable of handing the current and to have a 45amp fuse fitted (rather than a 40amp). Is a standard 3 bed semi likely to have the necessary wiring, I presume the fuse they mention is in the ceiling cord pull switch?

I appreciate the advice, always difficult to give when descriptions are from the inexperienced!

What size is the cable feeding the existing shower? A 10.8kW unit is going to need 10mil cable.

SineWave will be able to advise, but an RCBO might be a better idea for protecting a power shower circuit.
Leo

Leo said:

What size is the cable feeding the existing shower? A 10.8kW unit is going to need 10mil cable.

SineWave will be able to advise, but an RCBO might be a better idea for protecting a power shower circuit.
Leo

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Thanks Leo, when you say 10mil, so you mean that flat grey cable that about 10mm across? The shower circuit has a seperate circuit breaker in the "fuse" box alright, I just assume that there is also a fuse in the ceiling switch.

1. Regarding the immersion, it could end up being drained by error as it won't be getting a supply, so basically make sure elements do not get turned on and burnt out.

2. Tying the ballcock to a rafter will have the same result as isolating mains water supply.

3. You are now moving towards 47amps for your 10.8Kw shower. More than likely, your cable is only 6mm, your isolating switch 45amps and your fuseboard protection 45amps, so Leo is spot on.
You are possibly looking a re-run of cable, fusing and switching. No, the switch would not have fusing as standard.

6mm is the cross-sectional-area and may be imprinted along the grey sleeving somewhere. You are better off getting a small known sample of 6 or 10 cable and comparing to existing.

Have you considered leaving shower at 8.5Kw

SineWave said:

Have you considered leaving shower at 8.5Kw

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I am now! I never considered the potential consequences when buying the 10.8kW, looks like I'll have to take it back and swap for an 8.5kW, my wife was looking forward to a better flow rate, however at least the 8.5 is cheaper. Many thanks to all for the advice, particularly Sinewave.