What type of shower is cheapest to use

plumb1_2

Is a electric shower or a shower off a Combi boiler cheaper to use ?

Section62

plumb1_2 said:

Is a electric shower or a shower off a Combi boiler cheaper to use ?

It depends on so many different factors... there's no one right answer.

Probably more important than cost is which (in the circumstances of the household using it) gives at least an adequate showering experience.

grumbler

plumb1_2 said:

Is a electric shower or a shower off a Combi boiler cheaper to use ?

Electricity is about 4 times more expensive for heating water than gas. For the same flow rate, electric shower is about 4 times more expensive to run, but the maximum flow of electric shower is lower (otherwise the water temperature drops). So, with a powerful boiler normal shower can be more expensive to run if it allows very high flow rates and if it is used at very high flow rates.

Bendy_House

I'd imagine as Grumb says; for the same delivered VOLUME of water, gas must surely be considerably cheaper?

Not as 'efficient' in converting the fuel to heat, but way more than compensated for by the lower energy cost.

Section62

Bendy_House said:

I'd imagine as Grumb says; for the same delivered VOLUME of water, gas must surely be considerably cheaper?

Not as 'efficient' in converting the fuel to heat, but way more than compensated for by the lower energy cost.

Only if the cost of electricity is 4x the cost of gas and the (gas boiler) system efficiency is at least 25%. (or equivalences of those numbers.)

For starters, the gas-system cannot deliver exactly the same volume of hot water as the electric shower because (depending on circumstances) there will be a volume of cold water to be run off first, and a volume of unusable hot water left at the end.  The volumes will vary depending on how close the boiler is to the shower.

As I said, there's no one right answer because in practical terms there is so much variability in circumstances.

The cost of gas vs cost of electric makes people overlook all the other factors that need to be taken into account - not forgetting the cost of wasted water if on a metered supply.

grumbler

Section62 said:

Bendy_House said:

I'd imagine as Grumb says; for the same delivered VOLUME of water, gas must surely be considerably cheaper?

Not as 'efficient' in converting the fuel to heat, but way more than compensated for by the lower energy cost.

not forgetting the cost of wasted water if on a metered supply.

Come on ... Why make things more complicated than they actually are?

Water costs about 1p/10L (?), and volume of 10 meters of 15mm pipe is just 5L. About 10L if it's 22mm pipe (very unlikely). So, for 10 meters of pipe we are talking about extra 1-2p when electric shower at the max power cost about 5p/min.

Section62

grumbler said:

Section62 said:

Bendy_House said:

I'd imagine as Grumb says; for the same delivered VOLUME of water, gas must surely be considerably cheaper?

Not as 'efficient' in converting the fuel to heat, but way more than compensated for by the lower energy cost.

not forgetting the cost of wasted water if on a metered supply.

Come on ... Why make things more complicated than they actually are?

Water costs about 1p/10L (?), and volume of 10 meters of 15mm pipe is just 5L. About 10L if it's 22mm pipe (very unlikely). So, for 10 meters of pipe we are talking about extra 1-2p when electric shower at the max power cost about 5p/min.

So you are saying it would be cheaper to run the shower in my garden room from the gas combi boiler 40m away in the kitchen, rather than having an electric shower? (*extreme example)

If not, then the OP's question is 'complicated'.  And completely ignoring relevant factors (such as wasted water) because they don't fit a preferred 'right' answer isn't doing the question justice.

I also think 5 litres per 10m of 15mm pipe is rather generous....

twopenny

One consideration is that a power cut will mean no shower. 
While gas driven will remain - so far.

Section62

twopenny said:

One consideration is that a power cut will mean no shower. 
While gas driven will remain - so far.

...not if it is a combi as the OP says.

But if the options are widened to include a system boiler, and you aren't reliant on a shower pump, then showering during power cuts would be a (time limited) option.

Norman_Castle

twopenny said:

One consideration is that a power cut will mean no shower. 
While gas driven will remain - so far.

I might be wrong but I think gas boilers need electricity to work.

GDB2222

Section62 said:

grumbler said:

Section62 said:

Bendy_House said:

I'd imagine as Grumb says; for the same delivered VOLUME of water, gas must surely be considerably cheaper?

Not as 'efficient' in converting the fuel to heat, but way more than compensated for by the lower energy cost.

not forgetting the cost of wasted water if on a metered supply.

Come on ... Why make things more complicated than they actually are?

Water costs about 1p/10L (?), and volume of 10 meters of 15mm pipe is just 5L. About 10L if it's 22mm pipe (very unlikely). So, for 10 meters of pipe we are talking about extra 1-2p when electric shower at the max power cost about 5p/min.

So you are saying it would be cheaper to run the shower in my garden room from the gas combi boiler 40m away in the kitchen, rather than having an electric shower? (*extreme example)

If not, then the OP's question is 'complicated'.  And completely ignoring relevant factors (such as wasted water) because they don't fit a preferred 'right' answer isn't doing the question justice.

I also think 5 litres per 10m of 15mm pipe is rather generous....

It depends on the pipe wall thickness, but I make it around 0.15 litres per metre. 

A combi boiler is normally going to be far cheaper,  although it's possible to find extreme cases where that's not true.