Replace Shower - Bar

[morg]

Hi all, thinking about getting a new shower, mira divisa 9.8.

The electrical side of it looks to be ok, just change fuse from 40A to 45A (hopefully ) (will be done by someone qualified).

But I am worried the plumbing isn't good enough.

The current shower is fed from the water tank by 15mm copper pipe, which is about 4 feet distance from shower inlet (height). So I guess this makes it around 0.2 bar?

Shower Requirements:
Plumbing

Minimum maintained inlet pressure for 9.0kW and 9.8kW, 70 kPa (0.7 bar)
for satisfactory operation

Maximum static inlet pressure 1000 kPa (10 bar)

Minimum static pressure 20 kPa (0.2 bar) to keep the inlet valva closed.

Will anything need to be done/upgraded? if the pressure does need raising, are there any other ways to raise the pressure with highering water tank etc?

Thanks

 

[bengasman]

You can't just change the fuse to a higher rating without risking overheating of the cable.
The cable in itself might look big enough, but if it runs through insulation, the rating may go down by as much as 50%.

 

[morg]

You can't just change the fuse to a higher rating without risking overheating of the cable.
The cable in itself might look big enough, but if it runs through insulation, the rating may go down by as much as 50%.

Thanks for posting, did not think about the cable requirements.

The current shower is at least 8.5kW ??? (Triton Rapide 3), it works fine by the way.
Not too sure what the cable is rated at, no indication on cable either.

How can I tell if it will good enough?

 

[bengasman]

Apart from physically following the cable from end to end, and checking if it goes through anything insulating, there is no way of telling. You will just have to assume the current rating is the maximum.

 

[morg]

Hi, thanks for posting

I know exactly where it goes, I 'assisted' an old electrician fit it a few years back, drilled the holes, fed it through, he connected the two ends then

through anything insulating

sorry you've lost me, can you give me an example???

I know it runs straight from shower to cu, no joins or nothing

thanks

 

[dextrous]

Anything insulating includes insulation (such as under rockwool) or embedding within plaster (without any trunking). Basically restricting airflow around it.

How old is the cabling, and does the consumer unit have RCD protection?
You could carry on asking here, or put a post on the electrics forum etc, etc, but to be quite honest I think your best bet is to get a local electrician to advise since the responses on here will probably become technical and argumentative, based on past experience

With regard to the water supply, 10m head gives you 1 bar, so 4 feet (1.2m) will give you about 0.12bar, so it's a bit low.

 

[dextrous]

Whether the existing shower pipework is run as a dedicated outlet from the water tank or as a tee off from cold water supply down to the cylinder or other gravity fed taps, amending it so you get mains supply should be quite easy by cutting through the supply pipe to the shower as close as possible to the tee or the water tank outlet to prevent dead-legs, and installing a tee into the mains supply pipe which feeds the water tank itself. Shove an isolator valve (preferably full bore) onto this new junction and use plastic pipes to connect to the existing tail, if you want to avoid copper.

This assumes that the existing mains pressure is adequate enough, which as it is sufficient to lift water up to the tank in the loft anyway, indicates it probably is anyway. Should be better that 0.2bar at least anyway.

 

[bengasman]

Anything insulating includes insulation (such as under rockwool) or embedding within plaster

Embedding in plaster is not counted as insulation
Insulating materials are mainly things like rockwool, foam, and whatever else is used for thermal and sound inuslation, but could be wood if a longer stretch through a small hole.
There is a number of other requirements of course like mentioned above.
A RCD is now always compulsory for shower, as is supplementary bonding, and main bonding.

 

[dextrous]

Anything insulating includes insulation (such as under rockwool) or embedding within plaster

Embedding in plaster is not counted as insulation

Oops

 

[kirkgas]

Whether the existing shower pipework is run as a dedicated outlet from the water tank or as a tee off from cold water supply down to the cylinder or other gravity fed taps, amending it so you get mains supply should be quite easy by cutting through the supply pipe to the shower as close as possible to the tee or the water tank outlet to prevent dead-legs, and installing a tee into the mains supply pipe which feeds the water tank itself. Shove an isolator valve (preferably full bore) onto this new junction and use plastic pipes to connect to the existing tail, if you want to avoid copper.

This assumes that the existing mains pressure is adequate enough, which as it is sufficient to lift water up to the tank in the loft anyway, indicates it probably is anyway. Should be better that 0.2bar at least anyway.

another consideration will also be will the old tank fed pipe take new mains pressure? i have seen many problems when old systems were connected to combis and the old hot supplies couldn't take the increase with the inevitable leaks

 

[dextrous]

another consideration will also be will the old tank fed pipe take new mains pressure? i have seen many problems when old systems were connected to combis and the old hot supplies couldn't take the increase with the inevitable leaks

True - I was "assuming" (very dangerous, will I ever learn!) that the tank being about 4' above the shower meant a short run of pipe which was installed fairly recently alongside the wiring at that time!