Electric shower available as 9.5kW or 10.8kW

Yup that is more like it...

In response to the actual point though, there are differences between "close but different" shower power ratings, and it is not just the allowance for variability in supply voltage. The makers usually make units for the common sizes of MCB - so 32, 40, 45, 50A etc. If you buy one, then they will also likely give you a power output range that is linked to the actual (rather than design) supply voltage. So you can show that a lower power shower can deliver the same output as a higher one if the former is on the higher end of possible supply voltages, and the reverse is true for the higher power one. That does not mean they have the same design specs though.

Showers destined for the UK market usually express their power based on an assumed 240V supply rather than the typical design voltage of 230V, since 240V is what the grid supplies.

(It was just the spec that was "tweaked" to allow out normal supply voltage to fit into the "common" European 230V nominal value - we changed our voltage limits from 240V +/- 6% to 230 +10%/-6% - however we did not change the actual supply voltage).

I don't have a thermostatic mixer, but the piping from my shower to my hot water tank is about 50cm long. That is good. Turn it on and it comes out hot, no waiting.

It's not powered, with only about 3m head, so you always want it on full pressure, but it is enough for me. Simple.

Our current 10.8kW Mira gives a decent hot shower in colder weather than we have now.

The flow is nothing like the pathetic trickle from a 3 KW Triton shower I remember when I was growing up decades ago.

Presumably a combi boiler won't support a power shower and they seem to be the most popular boiler these days.

Why would a combi feed a power shower? It's giving you hot at mains pressure, just feed that and mains cold into a thermostatic mixer shower ...

Having experienced that sort of shower in various locations, I'll agree with that. But retro-installing in a bathroom that has already been expensively re-tiled (etc), with a 20' run from the gas boiler, is a daunting task.

HP for measuring the output of an non-motive electrical system?

Ah well... there's another reason why a power shower isn't available to us.

But 3kW? That's not a lot, is it?

why not? kW are used for EVs

Power is power, no matter whether it is motive or not.

Horses used to tread mills to thresh corn etc etc

Imperial power would be something like foot-pounds per second.

Electrical power has always been the Watt, and it's always been SI units.

It's a crazy old world innit?

SI units are quite recent. Before them was the MKS sysytem ( when I was at university). and before that was the CGS system (when I was at school|).

It appears Watts were a suggestion from the British Association to the international congress of electricians, to replace erg/s.

What really irks is that they split a 9kw into 5kw + 4kw rather than 6kw

• 3kw with 5kw being practically useless except in a heatwave. Got caught by that once so now read the specs before buying a replacement.

IIRC SI units *are* mks.

We didn't do much with cgs ever. It was a weird standard even then

yes, it isn't surprising that the UK is involved with internsational Standards

A HP is a unit of power like any other, where 1hp = 746W (or 750 for ease of reckoning!)

So it is only convention (or scale) that uses it in some cases and not others. Can't see ordering a 1k 1/2984 HP resistor will win you any favours!

There are those that will assure you that without the EU, there *are* no international standards.

Prats.

I don't know, 0.33 mhp sounds good?

History suggests otherwise:

Horsepower was a truly European standard unit of power. Of course each country defined it slightly differently!