Author Topic: Replacing an electric shower  (Read 10079 times)

Replacing an electric shower
« on: 24 October, 2016, 07:46:23 pm »
My electric shower is over 20 years old & now only produces lukewarm water, so it's got to be replaced. 

It's a direct feed 8.5W (Gainsborough 300) and I'd like to replace it with something similar.    Water feed is via an external pipe which enters from the right hand side, this is a brazed joint via an elbow to a vertical pipe.

I believe that if I replace it with another shower of the same rating I can do the wiring myself.   Is this correct ?

What's the best way to approach the piping ?  If I can de-braze the existing joint do I need to replace it with another of the same or can a push fit be used ? 

If I end up having to GAMI how much is it likely to cost ?   (My Dad did it last time, but I don't think he can manage the stairs anymore....)

Not fast & rarely furious

tweeting occasional in(s)anities as andrewxclark

Feanor

  • It's mostly downhill from here.
Re: Replacing an electric shower
« Reply #1 on: 24 October, 2016, 08:19:42 pm »
Replacing it with one of the same rating means that you don't need to look at upgrading the wiring.
When you ask can you do it yourself, I presume you mean the Part P stuff?

Regulation 12(6A) sets out electrical installation work that is notifiable. All other electrical installation work is not notifiable – namely additions and alterations to existing installations outside special locations, and replacements (like for like), repairs and maintenance anywhere (this includes special locations such as saunas, swimming pools and within the area of special location in a bathroom).

So you'd be OK doing like-for-like replacement.

Regarding pipework:
You just have to deal with it as best you can, and the best solution will be highly situation-dependant.
De-soldering an old elbow is of course possible.
I'd not want to use a push-fit onto a previously soldered stub of pipe unless you were able to wipe the solder off very well ( blowtorch followed with damp cloth using a quick twisting wipe towards the end of the pipe); I'd either solder onto the stub, or cut back the old pipe to un-soldered copper.
Sometimes it's easier to cut back some distance and run fresh pipe for the final approach, than trying to bodge the existing approach.


Re: Replacing an electric shower
« Reply #2 on: 24 October, 2016, 09:49:59 pm »
Just give the water bye laws a look see. May be necessary to install a NRV/isolation valve. Otherwise can't really see a problem. Mybuilder.com is perfect for obtaining quotes for GAMI. You cant go wrong with compression fittings tbh.
Get a bicycle. You will never regret it, if you live- Mark Twain

Vince

  • Can't climb; won't climb
Re: Replacing an electric shower
« Reply #3 on: 24 October, 2016, 09:57:58 pm »
I would be surprised if the water connection to the shower is via a soldered joint. If you take the cover off, does the copper pipe connect via a (plastic?) compression joint?
216km from Marsh Gibbon

Feanor

  • It's mostly downhill from here.
Re: Replacing an electric shower
« Reply #4 on: 24 October, 2016, 10:02:19 pm »
It won't be soldered internally within the shower ( that would melt the plastic! )
The internal connection will usually be a push-fit.
But the external pipework may have been made up and soldered in place such that the shower unit could then sit onto it.

Re: Replacing an electric shower
« Reply #5 on: 24 October, 2016, 10:29:49 pm »
The vertical riser pipe has an isolation valve fitted, I can't recall if we did that when swapping out the old unit!   There is  a copper stub sticking out from the body of the shower unit which is soldered to the pipe.  If that's push fit internally then it would simplify matters.  Time to get the case off and  have a look!
Not fast & rarely furious

tweeting occasional in(s)anities as andrewxclark

Feanor

  • It's mostly downhill from here.
Re: Replacing an electric shower
« Reply #6 on: 24 October, 2016, 10:45:13 pm »
That simplifies matters.

It means that whatever, you can just chuck the old pipework from above the isolation valve.
Make up new pipework to suit the new shower.
Make it up in-situ, and then remove it and solder it elsewhere.
Mark alignments with a pencil if they are likely to rotate.
Bring the made-up assembly back, and install it between the isolation valve and the new shower.

Re: Replacing an electric shower
« Reply #7 on: 29 October, 2016, 11:21:26 am »
Back to this again I'm afraid.  Taking the cover off the existing shower shows that it's actually a 7Kw shower, which restricts the number of available direct replacements.

On reading up it appears that 8.5kw showers & above need 10mm2 wiring, I think I've only got 6mm2. 
It's on a 30A breaker, will that need upgrading as well ?




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Not fast & rarely furious

tweeting occasional in(s)anities as andrewxclark

Re: Replacing an electric shower
« Reply #8 on: 29 October, 2016, 12:26:54 pm »
Mira still do a 7.5kw. According to Mira is UK's best selling shower.
Get a bicycle. You will never regret it, if you live- Mark Twain

Kim

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Re: Replacing an electric shower
« Reply #9 on: 29 October, 2016, 12:39:59 pm »
Mira still do a 7.5kw. According to Mira is UK's best selling shower.

Best selling == popular with landlords who don't have to use it, thobut.

OTOH there's not a lot to an electric shower, and if the current 7kW one is adequate, that's probably the best approach.

Re: Replacing an electric shower
« Reply #10 on: 29 October, 2016, 12:46:37 pm »
Miras are not cheap. Shop around, huge variances.
Get a bicycle. You will never regret it, if you live- Mark Twain

rogerzilla

  • When n+1 gets out of hand
Re: Replacing an electric shower
« Reply #11 on: 29 October, 2016, 12:55:43 pm »
Do you have a combi boiler, and is it an over-bath shower?  If so, mixer taps and a diverter valve will be cheaper to buy, cheaper to run and a lot less hassle.  The Beta taps from Homebase are absolutely fine for £50.  If you're all-electric then I commiserate you  :(
Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.

Re: Replacing an electric shower
« Reply #12 on: 29 October, 2016, 12:59:53 pm »
The 7.5kw Mira appears to be left side only for the water inflow, so not suitable.   Now looking at Tritons.

I'm on the 4th floor & water pressure isn't the best up here, that restricts me to a fairly low powered unit as well.
Not fast & rarely furious

tweeting occasional in(s)anities as andrewxclark

Re: Replacing an electric shower
« Reply #13 on: 29 October, 2016, 01:14:44 pm »
The 7.5kw Mira appears to be left side only for the water inflow, so not suitable.   Now looking at Tritons.

I'm on the 4th floor & water pressure isn't the best up here, that restricts me to a fairly low powered unit as well.

If your water pressure is ok when the shower is on cold then it's fine regardless of what kw unit you install.
The bigger the bang as regards kw then the bigger the buck in your leccy bill basically.
It depends how easy[often not very] it is to route a new 10mm supply from CU to shower. If the distance is not huge and access is straightforward then maybe it's worth doing, but 10mm cable is stubborn stuff to work with. You'll need a 45amp breaker as well.
Garry Broad

Vince

  • Can't climb; won't climb
Re: Replacing an electric shower
« Reply #14 on: 29 October, 2016, 01:23:46 pm »
Do you have a combi boiler, and is it an over-bath shower?  If so, mixer taps and a diverter valve will be cheaper to buy, cheaper to run and a lot less hassle.  The Beta taps from Homebase are absolutely fine for £50.  If you're all-electric then I commiserate you  :(
This is what we did when the insides of our shower melted!
Currently looking for a thermostatic bath tap with diverter valve.
216km from Marsh Gibbon

Re: Replacing an electric shower
« Reply #15 on: 29 October, 2016, 01:34:27 pm »
A suitable 7.5kW Triton is available for £89, this seems the simplest & cheapest option.

The Plumbworld site says  http://www.plumbworld.co.uk/electric-showers-65-0000

 "As electric showers can range from 7.5kW all the way to 10.8kW, they all have differing demands on the power supply. In general, all showers that have a power rating greater than 9kW will require cabling to be upgraded from the regular 6mm to 10mm. However, if the shower you buy is 9kW or below, the standard 6mm cables connecting your shower to your electric supply will be suitable. It is advised that a professional electrician is consulted prior to the installation of the shower to ensure all criteria and safety checks are met."

Other sites say that an 8.5kW need 10mm cabling  ???   A replacement cable would be a fairly short run via the loft, but I've a feeling there is a lot of junk in that part of the loft, including the old huge & unused cast iron water tank!
Not fast & rarely furious

tweeting occasional in(s)anities as andrewxclark

Kim

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Re: Replacing an electric shower
« Reply #16 on: 29 October, 2016, 01:37:21 pm »
I've a feeling there is a lot of junk in that part of the loft, including the old huge & unused cast iron water tank!

You could fill it with water and have a decent shower...  :)

jiberjaber

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Re: Replacing an electric shower
« Reply #17 on: 29 October, 2016, 01:44:33 pm »
The rating of the cable is also effected by the medium it passes through, i.e. cable in free air relative to cable buried in a wall, this is why you may need to "consult with an electrician" as they will be able to assess based on cable run length and the like to understand any de-rating that needs to be applied.... in short, in lieu of having a chat with an electrician, the safest bet is to opt for 10mm. 

Also don't underestimate the difficulty in handling 10mm vrs 6mm cable it's a lot harder to bend etc - so where a 6mm might fit nicely at the moment, it might be harder to get a 10mm cable in there.  :)
Regards,

Joergen

Re: Replacing an electric shower
« Reply #18 on: 29 October, 2016, 01:52:19 pm »
I've a feeling there is a lot of junk in that part of the loft, including the old huge & unused cast iron water tank!

You could fill it with water and have a decent shower...  :-)

I could have a bath in the damn thing!    These flats are 1930's council tenements & used to be 5 floors with water tanks in the loft.  When Barratt's did their cheap & nasty "award winning" renovation in the 1980's they took the top floor off but couldn't be bothered moving the tanks downstairs.  It makes a handy junk store.

Not fast & rarely furious

tweeting occasional in(s)anities as andrewxclark

rogerzilla

  • When n+1 gets out of hand
Re: Replacing an electric shower
« Reply #19 on: 29 October, 2016, 02:12:12 pm »
Asbestos cement tank?  My parents took one out of their old loft during a roofing job and it became a kind of storage bin in the garage.  Avoided having to cut it up in a Noddy suit, anyway.
Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.

Re: Replacing an electric shower
« Reply #20 on: 29 October, 2016, 05:05:16 pm »
A suitable 7.5kW Triton is available for £89, this seems the simplest & cheapest option.

No doubt.

The Plumbworld site says  http://www.plumbworld.co.uk/electric-showers-65-0000

 "As electric showers can range from 7.5kW all the way to 10.8kW, they all have differing demands on the power supply. In general, all showers that have a power rating greater than 9kW will require cabling to be upgraded from the regular 6mm to 10mm. However, if the shower you buy is 9kW or below, the standard 6mm cables connecting your shower to your electric supply will be suitable."

Oh dear. Proof reader must have gone walkabouts.
Folk reading that for the first time are going to get mightily confused when they start talking to people that believe this:

Other sites say that an 8.5kW need 10mm cabling  ???
Garry Broad

rogerzilla

  • When n+1 gets out of hand
Re: Replacing an electric shower
« Reply #21 on: 29 October, 2016, 06:57:56 pm »
ISTR that MCBs are treated more generously than fuses when it comes to showers; you can go a little above the theoretical current capacity of the circuit,  because the MCB will trip reliably at the rated current + some known margin, where a fuse might allow +50% for an ectended period.  Regs may well have changed, though.
Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.

Kim

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Re: Replacing an electric shower
« Reply #22 on: 29 October, 2016, 07:02:45 pm »
Anyone else find the apparent absence of an RCD (unless there's one upstream of that isolator switch) unnerving?

It is, after all, a shower...

rogerzilla

  • When n+1 gets out of hand
Re: Replacing an electric shower
« Reply #23 on: 29 October, 2016, 07:44:09 pm »
Personally I'd always prefer a 30mA one near the shower rather than relying on an RCD in the consumer unit.  Having said that, I've had a couple of houses with instantaneous electric showers and no RCD anywhere.
Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.

Re: Replacing an electric shower
« Reply #24 on: 30 October, 2016, 07:22:22 am »
Anyone else find the apparent absence of an RCD (unless there's one upstream of that isolator switch) unnerving?

It is, after all, a shower...
Just be glad it won't be one of these:-
https://www.youtube.com/watch?v=cNjA0aee07k
Quote from: Kim
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