New shower installation - options

BUFF

DanielDeronda said:

Will be very difficult to put the shower in a separate place to the bath, I'm in a compact flat.

So, I am reading that as your shower is over your bath? Could you upgrade your bath taps (presumably run from your combi) to a thermostatic bath/shower mixer?

What combi do you have (check dhw flow rates)?

ThisIsWeird

BUFF said:

DanielDeronda said:

Will be very difficult to put the shower in a separate place to the bath, I'm in a compact flat.

So, I am reading that as your shower is over your bath? Could you upgrade your bath taps (presumably run from your combi) to a thermostatic bath/shower mixer?

What combi do you have (check dhw flow rates)?

D'oh! A good idea.

DD, the age of your current shower coupled with the fact it's a hard water area would very likely have your shower at the end of its life - lawdie, it's done well.

Make, model and photo of shower, please? And does the cold tap in the bathroom gush pretty strongly?

Make, model and photo of combi boiler too, please.

Your options would appear to be:

1) Swap your current leccy shower with one of the same rating. Pros - cheapest solution. Cons - the resulting shower will still be leccy-pants. But if you are happy with your leccy shower when it's working fine, then cool.

2) Check the size of cable supplying the shower, and see if there's any room to upgrade the shower to a more powerful model. It'll make a 'difference'. But not much.

3) Run a new 10mm power cable to a new 10.8kW electric shower, which is the biggest you can get. It should then be 'ok', but nothing special.

Or, remove the leccy shower and run one off a combi:

4) BUFF's idea of replacing your bath taps with a thermostatic shower mixer deck. This will have a control to swap from 'taps' to 'shower'. Usually a flexible hose then goes to a handset on a rail as before. This will give you a shower around 3 times more powerful - a huge difference. It won't cost any more to run.

5) Take a hot pipe up t'wall from below the bath, alongside the existing cold one, and fit a thermo shower mixer on the wall. This will not perform any better than the bath deck mixer, but will look a bit better and be easier to control - it'll be right in front of you. A lot more work to fit, tho'.

Bear in mind that if you remove swap from leccy shower to thermo mixer, you'll have to remove the old leccy shower and make good the wall.

If you go combi-powered, then make sure the shower is a 'thermostatic' type.

CSI_Yorkshire

ThisIsWeird said:

CSI_Yorkshire said:

ThisIsWeird said:

CSI_Yorkshire said:

ThisIsWeird said:

If the mains cable supplying your leccy shower is the larger 10mm2, then you should be able to fit the most powerful 10.8kW(?) unit, so that should be an improvement (provided your water supply is ok). How close is your CU ('fuse box') to your bathroom?)

No no no no no.  "Should" here translates as "I would like to set my house on fire".

Eek! Sorry, I don't understand.

10mm2 might be enough for a 10.8kW - the cable by itself would, on paper, be big enough for that amount of load.

Doesn't take any account of the installation method though.  If the cable was running through a notch in a joist with several others, or if it happened to run through some insulation (many people have added extra loft insulation covering cables), how much current the cable can carry without overloading goes down.

Some examples - if 5cm of the cable goes through loft insulation, you lose 11% of the capacity.  At 40cm of cable in insulation, you have lost 45% of the capability.  If there are 3 cables bunched together (and each is likely to be more than 30% loaded) then you lose 30% of the capability.

These things can easily be enough to make a "big enough" cable actually not big enough at all.

The shower manufacturers all ignore this in their online help pages - so many people assume it will all be ok - but they will all have something in the instructions that say "cable sizing is just a guide and your circumstances should be checked by a qualified electrician" or something like that.

Phew - good job I said 'should', then, and not 'will' :-)

(Seriously - a 2" run of cable in insulation reduces the carrying capacity by over 10%? A footandahalf is nearer 50%?!)

Yep.  Here's the table:



I've seen exactly this thing happen several times - note the username

ThisIsWeird

CSI_Yorkshire said:

ThisIsWeird said:

CSI_Yorkshire said:

ThisIsWeird said:

CSI_Yorkshire said:

ThisIsWeird said:

If the mains cable supplying your leccy shower is the larger 10mm2, then you should be able to fit the most powerful 10.8kW(?) unit, so that should be an improvement (provided your water supply is ok). How close is your CU ('fuse box') to your bathroom?)

No no no no no.  "Should" here translates as "I would like to set my house on fire".

Eek! Sorry, I don't understand.

10mm2 might be enough for a 10.8kW - the cable by itself would, on paper, be big enough for that amount of load.

Doesn't take any account of the installation method though.  If the cable was running through a notch in a joist with several others, or if it happened to run through some insulation (many people have added extra loft insulation covering cables), how much current the cable can carry without overloading goes down.

Some examples - if 5cm of the cable goes through loft insulation, you lose 11% of the capacity.  At 40cm of cable in insulation, you have lost 45% of the capability.  If there are 3 cables bunched together (and each is likely to be more than 30% loaded) then you lose 30% of the capability.

These things can easily be enough to make a "big enough" cable actually not big enough at all.

The shower manufacturers all ignore this in their online help pages - so many people assume it will all be ok - but they will all have something in the instructions that say "cable sizing is just a guide and your circumstances should be checked by a qualified electrician" or something like that.

Phew - good job I said 'should', then, and not 'will' :-)

(Seriously - a 2" run of cable in insulation reduces the carrying capacity by over 10%? A footandahalf is nearer 50%?!)

Yep.  Here's the table:



I've seen exactly this thing happen several times - note the username

Ah! Buried to a DEPTH of 50mm throughout its WHOLE length? Phew :-)

Eldi_Dos

So would it be good practice to enclose electric cables in a plastic trough with a lid before installing the recommended depth of insulation.
Or better to leave cables above the insulation.

CSI_Yorkshire

ThisIsWeird said:

CSI_Yorkshire said:

ThisIsWeird said:

CSI_Yorkshire said:

ThisIsWeird said:

CSI_Yorkshire said:

ThisIsWeird said:

If the mains cable supplying your leccy shower is the larger 10mm2, then you should be able to fit the most powerful 10.8kW(?) unit, so that should be an improvement (provided your water supply is ok). How close is your CU ('fuse box') to your bathroom?)

No no no no no.  "Should" here translates as "I would like to set my house on fire".

Eek! Sorry, I don't understand.

10mm2 might be enough for a 10.8kW - the cable by itself would, on paper, be big enough for that amount of load.

Doesn't take any account of the installation method though.  If the cable was running through a notch in a joist with several others, or if it happened to run through some insulation (many people have added extra loft insulation covering cables), how much current the cable can carry without overloading goes down.

Some examples - if 5cm of the cable goes through loft insulation, you lose 11% of the capacity.  At 40cm of cable in insulation, you have lost 45% of the capability.  If there are 3 cables bunched together (and each is likely to be more than 30% loaded) then you lose 30% of the capability.

These things can easily be enough to make a "big enough" cable actually not big enough at all.

The shower manufacturers all ignore this in their online help pages - so many people assume it will all be ok - but they will all have something in the instructions that say "cable sizing is just a guide and your circumstances should be checked by a qualified electrician" or something like that.

Phew - good job I said 'should', then, and not 'will' :-)

(Seriously - a 2" run of cable in insulation reduces the carrying capacity by over 10%? A footandahalf is nearer 50%?!)

Yep.  Here's the table:



I've seen exactly this thing happen several times - note the username

Ah! Buried to a DEPTH of 50mm throughout its WHOLE length? Phew :-)

That's not what it says.  The column label is "Length in insulation".  Not depth.

Eldi_Dos said:

So would it be good practice to enclose electric cables in a plastic trough with a lid before installing the recommended depth of insulation.
Or better to leave cables above the insulation.

In conduit, in contact with a joist/beam/the plasterboard, and above the insulation are all "better" (i.e. there is less loss of rating) than completely surrounded by insulation.

To get the full rating, it's "clipped directly onto an exposed surface (like the wall)".

All in the wiring regulations (mainly Appendix 4) - so the electrician who you consult should do the right maths and make sure the cable is the right size.

DanielDeronda

The make & model of my combi gas boiler is a Vaillant Ectotec Pro 24, on the wall in my lounge, as the kitchen wasn't really possible.

The make & model of my electric shower is a Triton Biarritz, obviously discontinued. On the wall in the bathroom on tiling.

The water flow from my bathroom taps is pretty decent.

I've cleaned the showerhead in white vinegar to reduce limescale but no visible improvement.

DanielDeronda

BUFF said:

DanielDeronda said:

Will be very difficult to put the shower in a separate place to the bath, I'm in a compact flat.

So, I am reading that as your shower is over your bath? Could you upgrade your bath taps (presumably run from your combi) to a thermostatic bath/shower mixer?

What combi do you have (check dhw flow rates)?

According to Vaillant website the DHW flow rate is 9.6 litres per minute for the Evotec Pro 24 boiler.

https://www.vaillant.co.uk/for-installers/products/ecotec-pro-24-28-and-30kw-3776.html

ThisIsWeird

DanielDeronda said:

BUFF said:

DanielDeronda said:

Will be very difficult to put the shower in a separate place to the bath, I'm in a compact flat.

So, I am reading that as your shower is over your bath? Could you upgrade your bath taps (presumably run from your combi) to a thermostatic bath/shower mixer?

What combi do you have (check dhw flow rates)?

According to Vaillant website the DHW flow rate is 9.6 litres per minute for the Evotec Pro 24 boiler.

https://www.vaillant.co.uk/for-installers/products/ecotec-pro-24-28-and-30kw-3776.html

That's a smaller combi, but once you've added a blend of cold water - say another 3-4 litres - it'll will be hugely better than your electric shower. And it won't cost any more to run.
Swapping your existing bath taps for a 'thermo shower deck mixer' must be the best solution, if cost vs performance is the requirement. 

ThisIsWeird

Found this but haven't read it yet:

https://www.buyaparcel.com/blog/replacing-a-triton-electric-shower-like-for-like.html