What type of shower is cheapest to use

Section62

Bendy_House said:

Section62 said:

In a similar vein, who said anything about gas?

Someone should have, as it's the one-word answer to this thread

(Yeah yeah yeah, it's 'combi', but you know what I mean...)

Grumbler suggests 5p/min for an electric shower - so say 10.5kW at a cost of 28.5p per kWh.

And he suggests an electric/gas cost ratio of about 4x.

So that data suggests gas per output kWh would cost about 7.1p  (ignoring the electrical costs of running the gas boiler)

How much does gas cost per output kWh in (say) the IV47 postcode area?

Does that one-word answer still apply?

Bendy_House

Section62 said:

Bendy_House said:

Section62 said:

In a similar vein, who said anything about gas?

Someone should have, as it's the one-word answer to this thread

(Yeah yeah yeah, it's 'combi', but you know what I mean...)

Grumbler suggests 5p/min for an electric shower - so say 10.5kW at a cost of 28.5p per kWh.

And he suggests an electric/gas cost ratio of about 4x.

So that data suggests gas per output kWh would cost about 7.1p  (ignoring the electrical costs of running the gas boiler)

How much does gas cost per output kWh in (say) the IV47 postcode area?

Does that one-word answer still apply?

Probably not - but I'm bored now.

plumb1_2

What would the gas cost be to rise the cold water temperature of 5c to 35c plus in the long winter months we have in the UK. Compared to electric cost?

Bendy_House

plumb1_2 said:

What would the gas cost be to rise the cold water temperature of 5c to 35c plus in the long winter months we have in the UK. Compared to electric cost?

Surely the same ratio? So if gas is cheaper in mild weather, then it'll ditto in cold?

Can I ask why you are wondering about this? I'd have thought that in the scheme of things - with heating and cooking presumably being larger consumers of energy - how much difference it might make?

grumbler

plumb1_2 said:

What would the gas cost be to rise the cold water temperature of 5c to 35c plus in the long winter months we have in the UK. Compared to electric cost?

Are you serious? To rise the temperature of what amount of water?

And why do you need absolute figures and only for winter when you already have the relative one - electricity cost will be about 4 times as high as the the gas cost, other things being equal, .

daveyjp

I've just seen an advert for Triton showers and they state their electric showers are cheaper to use than a shower using water from a combi.

Maybe contact them and ask for their workings.

I suspect a lot of it is based on how much water each uses and the costs of the water and treatment charges, not just the method of heating the water.

northernsoul

Rather than guess I have done some tests. Mostly done last May but a good indicator of costs.
I have a Vaillant 837 28kw combination boiler. The water temperature is set at 45C.

At the new rate of 7.33/kWh these are the costs I found for various lenghts of showers ( from actual gas meter readings)

I use a large rainforest shower head and the shower temperature is too high for some people so plenty hot enough (they turn it down from maximum temperature)

3 min shower  1.32kwh , 9.7p (one reading)

4 min shower 1.88kwh , 13.8p (average of 9 readings)

5 min shower 2.14kwh , 15.7p (average of 6 readings)

6 min shower 2.39kwh ,  17.5p (one reading)

Do not take showers longer than 6 minutes.

Note that after the 4 minute shower costs go up per 1 minute extra about 1.9p (so approximately 1.9p for every extra minute in shower - I guess).
For a normal shower head costs may be different.

The temperature is also hot enough for a very hot full bath (to overflow) which now costs 5.84kwh , 42.8p.

I believe the following calculation is correct for a 10kw electric shower for a comparison
6 minute shower = 10kw* 0.1 (6 minutes/60 minutes)*27p = 27p for a 6 minute electric shower

Hope this helps

ComicGeek

daveyjp said:

I've just seen an advert for Triton showers and they state their electric showers are cheaper to use than a shower using water from a combi.

Maybe contact them and ask for their workings.

I suspect a lot of it is based on how much water each uses and the costs of the water and treatment charges, not just the method of heating the water.

Triton have an Energy & Water savings calculator on their website that they've created alongside this. For our household that gives:

£468.65/yr for a mixer shower from a gas combi - £227.37 for water, and £241.27 for energy.
£427.95/yr for electric shower - £96.60 for water, and £331.35 for energy.

So using a tiny 8.5kW electric shower to limit the shower flow rate, thereby reducing water costs - the energy cost for electric showers is still significantly higher, even with a massive drop in flow rate. The mixer shower is modelled as 12 l/min, so could be easily reduced with flow regulators, or by turning it down.

Typical marketing tool of comparing apples with pears.

GDB2222

Section62 said:

Bendy_House said:

Section62 said:

In a similar vein, who said anything about gas?

Someone should have, as it's the one-word answer to this thread

(Yeah yeah yeah, it's 'combi', but you know what I mean...)

Grumbler suggests 5p/min for an electric shower - so say 10.5kW at a cost of 28.5p per kWh.

And he suggests an electric/gas cost ratio of about 4x.

So that data suggests gas per output kWh would cost about 7.1p  (ignoring the electrical costs of running the gas boiler)

How much does gas cost per output kWh in (say) the IV47 postcode area?

Does that one-word answer still apply?

I love these end cases.  

Norman_Castle

ComicGeek said:

daveyjp said:

I've just seen an advert for Triton showers and they state their electric showers are cheaper to use than a shower using water from a combi.

Maybe contact them and ask for their workings.

I suspect a lot of it is based on how much water each uses and the costs of the water and treatment charges, not just the method of heating the water.

Triton have an Energy & Water savings calculator on their website that they've created alongside this. For our household that gives:

£468.65/yr for a mixer shower from a gas combi - £227.37 for water, and £241.27 for energy.
£427.95/yr for electric shower - £96.60 for water, and £331.35 for energy.

So using a tiny 8.5kW electric shower to limit the shower flow rate, thereby reducing water costs - the energy cost for electric showers is still significantly higher, even with a massive drop in flow rate. The mixer shower is modelled as 12 l/min, so could be easily reduced with flow regulators, or by turning it down.

Typical marketing tool of comparing apples with pears.

https://www.tritonshowers.co.uk/calculator/savings

Mine shows, combi mixer shower £132.78 total or £80.30 with a flow regulator/low flow shower head.

Also shows £149 total costs for an electric shower vs £80 total costs for a mixer with a low flow.

Their calculator shows I can save about 40% of the cost by adding a flow regulator. It ignores the fact I've got a low flow shower head as I suspect many others have. As above, its not a fair comparison.

They also sell flow regulators for £10.47. Severn Trent used to offer these to customers for free, its possible other water suppliers also offer them.