This has been somewhat covered in a couple of recent threads but they are
long so I'm trying to pick up on a few points.

(1) The maximum power output of a UK electric shower is around 10 kW. The
output of a small(ish) combi boiler is around 28 kW. So the combi should
be able to apply 2.8 times the heat to incoming cold water and so (I
assume) heat 2.8 times the amount of incoming water to an acceptable
temperature compared to the electric shower.

(2) Electricity costs around 3 times gas (per unit of energy) which kind
of balances out. You can either have about 3 times the hot water in your
shower for the same price or save money each time you shower at lower flow
rates.

I think most people would go for the more satisfying shower which does
reduce/eliminate the cost saving from using a combi boiler.








{Wanders off into speculation}

Hmmm....what is the maximum (ignoring wiring restrictions for the moment)
that you could get out of a UK domestic 2 phase supply?

Simplistically, using (Volts * Amps = Watts) and rounding outrageously 4
amps = 1 kW.

So again rounding outrageously a 13 Amp circuit could support a 3 kW fire,
for example.

If your mains incomer is 60 amps (a lot go up to 100 amps) then you might
be able to draw (60/4) = 15 kW is nothing else is powered up, or (100/4) =
25 kW for a 100 amp supply.

I realise there are all sorts of minor (hah!) constraints but if you had a
100 amp incomer then is there any reason that you couldn't (with some very
thick cabling) take 60 amps for a shower giving you 15 kW of toasty
goodness?

I do note that taking all the output from a 100 amp incomer still gives
you less heat input than a combi boiler.

3 phase electric shower, anyone?

Cheers


Dave R

--
AMD FX-6300 in GA-990X-Gaming SLI-CF running Windows 7 Pro x64

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