Heatstore Multi-flow 12kw instead of shower

[timmy567]

Looking to replace an electric shower with a 12kw multi-flow instantaneous water heater from Heatstore. I've removed the old electric shower and all the wiring (cable far too small - needs 10mm2) and MCB from the consumer unit and was looking to procure all the parts required for the Heatstore.

The consumer unit I have is a MEM unit from the 80s and seems to only accept MCBs with a max rating of 45Amps (if I were to buy a second hand one from ebay as you cant get new ones to fit).

So I figure that the best thing to do would be to install one of these separate shower consumer units with built in RCD and a MCB rated to 50Amp (as per the MCB rating specified in the Heatstore installation manual). All of the 50Amp MCBs seem to be rated to 11Kw (MK units) or 11.5Kw (Wylex Units) max rating though, and I need 12kw.

Can anyone recommend a good brand of unit that will suit? or will this make much difference?

There is a crabtree unit in screwfix (starbreaker shower kit) but the spec they give you on their website is pretty basic and crabtrees own website is dung also. Looks not too bad for £41?

 

[securespark]

12 big ones @230 is 52.17A.

 

[timmy567]

I was just trying to go by the manufacturers instructions. Seems to be a bit of a misfit as the biggest electric showers you can get are 10.5 kw so I don't think a shower kit is made for a 12kw.

I thought a 50A MCB would suit better than a 63A MCB?

 

[timmy567]

Just checked my supply is only 60Amps fused prior to the meter. So the manufacturers recommended 50Amps will have to do. No moint in having a 63Amp MCB.

 

[Taylortwocities]

I spy that you are in Scotland so Part P does not apply.

However, i strongly suggest that you get a qualified spark in to look at the total loading in your house before proceeding further.
If the main fuse is 60A then you'll be over budget if you have a shower at the same time as someone switches on a kettle.

It may be a simple matter of having the lekky co upgrade the main fuse//....

 

[timmy567]

Thanks,

I'll need to get a Sparky in anyway as I will need a Helny box fitted to fit the Shower consumer unit and I cannot turn off the mains power to do this. I'll speak to my electrical supplier regarding the main fuse rating also.

 

[GaryMo]

I thought a 50A MCB would suit better than a 63A MCB?

If the loading is just over 52A?
How do you come to that conclusion? Convenience?

 

[ban-all-sheds]

a MCB rated to 50Amp (as per the MCB rating specified in the Heatstore installation manual).

That's how - 12kW at 240V is 50A.

12 big ones @230 is 52.17A.

Indeed, but what's the betting the 12kW rating of this device is at 240V?

And that if you run it at 230V it dissipates approx 11kW, and draws approx 48A?