Smart meter: some days starts with a big balance + a bath is cheaper than a shower?

[Harry Bloomfield]

Bath or a shower?
Which is cheaper?

A great deal depends on the type of shower, the flow rate and how long you run the shower for.

9.5Kw electric shower, for 2 minutes, at 33p per Kwh - around 10.4p, assuming the shower runs flat out for the entire period.

A bath full of really hot gas heated bath water costs around 30 to 40p.

Both are plus cost of the water if you are on a meter.

In winter I tend to make more use of the bath, because it has the effect of warming me up, and reducing the need for heating the house up.

 

[Brigadier]

cost of the water if you are on a meter.

OOI, what is the cost of water on the meter?

I've had a look, and it either gets confusing, or I'm overthinking it.
As in, the principle is "you only pay for what you use".
But the charges are stated as both for use i.e. what comes in, and waste i.e. what goes out.

Logic says that, for me to create waste water, I've had to pay for it already, "on the way in".

 

[Harry Bloomfield]

But the charges are stated as both for use i.e. what comes in, and waste i.e. what goes out.

It's charged separately, because not all properties have mains drainage.

My charge is around £2.90 per cubic meter, the most expensive component of which is the waste part. A bath needs around 75L, so the water, if on my meter, would cost around 21p on top.

 

[Brigadier]

It's charged separately, because not all properties have mains drainage.

My charge is around £2.90 per cubic meter, the most expensive component of which is the waste part.

But if you have mains drainage, waste water is not charged?

 

[Harry Bloomfield]

But if you have mains drainage, waste water is not charged?

Per cubic metre, they change me £1.29 for the incoming metered supply. Based on what fresh water I consume, they cannot measure it - they charge me £1.61 for disposal of waste water. Both added together is £2.90 per cubic metre - which is the sum I pay per metre consumed.

Rain water disposal is charged on top and at a fixed annual charge of £39. Rain water goes untreated into the streams and rivers, grey/waste water needs much more costly treatment than the fresh water they send to me.

 

[Justin Passing]

You can probably forget flow rates and temps if you aren't restricting the flow.
Your 35cdi combi boiler flat out will use almost 40kW so in 6 mins that's 4kWh or 44p.
Actual flow rate depends how hot you like the water. It's about 38°.
I don't know what flow rate they set on the boiler...

From stored water you'd have to measure your flow rate - mine's about 25l/min max on one shower which uses a 4.5bar pump, and another off an unvented is quite a bit less.
I only use them on low.
Baths (around 43°) vary in size, obvs.

 

[Deleted member 18243]

Someone has to pay for all those furloughs and "business loans".

 

[Ihavenojob]

The temperature of the incoming mains water will have some bearing on a combi.

 

[Justin Passing]

The temperature of the incoming mains water will have some bearing on a combi.

Applies to a bath of shower, though, it pretty much cancels out of the equation

 

[Ivor Windybottom]

If the bath is over the shower then next time put the plug in before. Shower as normal, see how much water is in the bath when you've done. There's your answer, the temperature is near enough the same either way, it will be cold after the shower but only because it's been blown through the air.

If the shower is using too much water then fit a screw-on flow restrictor to the hose. Most people don't notice the difference if you don't tell them, they're not stupidly slow.

I'm assuming you have a mixer shower - if it's electric then the comparison is completely different, as it costs much more than gas.

 

[Harry Bloomfield]

If the bath is over the shower

T'other way round!

There's your answer, the temperature is near enough the same either way, it will be cold after the shower but only because it's been blown through the air.

Showers tend to be run a few degrees hotter than bath water, because the water cools between the shower head and your skin.

I had been intending to satisfy my curiosity about bath water temperatures for months, and last week I remembered to take my calibrated digi-thermometer upstairs with me, to carry out some tests...

As hot as I could feel comfortable in, was 42.3C. After a soak, with the water seeming to cool, I checked it again and I was quite surprised to note it had only dropped in temperature to 40.5C - so my assumption was that my skin must become accustomed to the hotter water, rather than the water being that much cooler.

Shower as normal, see how much water is in the bath when you've done.

Good idea, another way, might be to just check the water meter, if you have one in a convenient place for reading.

 

[Ivor Windybottom]

Oh aye, shower over the bath!

So it sounds like you're agreeing in a very roundabout way that the temp of a bath is near enough the same as a shower. So if you stick the plug in before a shower then the amount of water at the end as a proportion of your typical bath depth is near enough the same as the proportion of the cost. If both are using the same hot water source of course.

Probably best not to pee in the shower during this experiment though. It may cure athlete's foot but it will also skew the results.

 

[Harry Bloomfield]

So it sounds like you're agreeing in a very roundabout way that the temp of a bath is near enough the same as a shower.

More or less, as I said - the shower water will tend to have to be slightly warmer, to account for the cooling of the drops as they fall through the air. The water which lands on my shoulders in the shower, is always obviously warmer than that which lands on my feet.

 

[jeds]

Shower costs?

During summer, my gas charge is for hot water only - no cooking or anything else. We averaged 300 to 350kWh last summer.
Taking 350kWh at the higher (current) rate (today's rate) of 10.43p per kWh + daily standing charge of 28.5p that averages at £1.50 per day.
There are 3 adults in the house and we shower every day, making approx shower cost something less than 50p. Obviously we do also draw a certain amount for cooking etc. but I reckon that's probably minimal in the calculation.

 

[Justin Passing]

Showers tend to be run a few degrees hotter than bath water,

It's the other way round. Bath temperatures are up to 45 (women like or can stand them hotter, due to surface body fat).
I can't stand anything near 45.

Showering is always close to 38°., not much difference m-f.
Delta T from incoming, varies with the season but over a fairly narrow range.
If Mains is say 10-15° then the max deltas range is between 15 to 38 = 23°
and 10 to 45 = 35°.

You really notice the winter flow temp if you have a weedy 7kW electric shower in a camp site!

If you want to improve your shower, either get a f-off pump like I did (Stuart Turner 4.5 bar - more than I ever use)
or a head which incorporates air. It makes it feel like there's a lot more volume of water.


Combis confound things because they quote numbers for a 35º rise. And many have a flow restrictor fixed to a specific flow rate. Usually a little rubber O ring which perishes/wears out.
If you turn the tap down you get more than a 35° rise.