I can work it out for my electric shower i.e. 9.5 kw @ 10p per kw/hour =
95/4 = 23.75p for a 15 min shower. But how would that compare to a WB 40 kw combi or a 28kw system boiler and high recovery cylinder / megaflow / thermal store ? I would imagine the combi being chaper to run but its 40 kw !!!Regards Jeff
kw/hour =
boiler and
No idea about cost but unless your washing your partner as well, 15 minutes seems far too long to me!
But you still use the same energy. So assuming boiler is say 85% efficient you can multiply the number of kilowatts used by 1/0.085 or whatever then multiply by the cost per kW of the gas and you'll find it's about one-third the price.
And why DO you need a 15 minute shower ? ;-)
so, disregarding heat exchanger losses etc you are saying that the amount of energy reqd to heat a volume of water is constant ?
Hmm, guestimate, got me thinking now, big job though, 6'6" and a dirty occupation :-)
Regards Jeff
I'm sure somebody will pick me up on something but yes.
Ah - not a two person shower then :-(
"Jeff" wrote | so, disregarding heat exchanger losses etc you are saying that the | amount of energy reqd to heat a volume of water is constant ?
Yes.
Can I guess you're under 35 and/or didn't do physics at school?
| > And why DO you need a 15 minute shower ? ;-) | Hmm, guestimate, got me thinking now, big job though, 6'6" and | a dirty occupation :-)
15 mins in shower. Water running for about half that.
Owain
Yes. What might reduce the electric shower costs to near gas levels (?) would be to fit a heat exchanger to take the output water from the shower, and use it to heat the incoming cold.
Or failing that splash out the 20p and enjoy a decent shower without being a tight wad! ;-)
Oh dawd. You'll start Drivel off again with his concentric copper pipes.
Because it takes that long in a 9.5kW electric-trickle shower to get the soap rinsed off!
I fear this is one area where he might actually be right. Gotta happen eventually.
Scream in pain as you are scalded by the first slug of really hot water out of the shower because it's a cheap electric one that doesn't have very good temperature control;-)
I often have a 15 minute shower - some times even longer! I find it a good way to unwind after a stressful day in the office! CM.
A shower that takes 10 litres/min of 55C hot water will consume 15 litres in 15 minutes. The shower will give approx 13 to 14 litres/mi with added cold
No. of Kilowatts = Quantity of water in litres x temp rise in degrees x Specific heat of water / No. of seconds in one hour.
Specific heat of water = 4.2
So to heat a 150 litres in 1 hour will take:
150 x 50 (raising water from 5C to 55C) x 4.2 /3,600 = 8.75 kWApply this formula to all the permutations
-- Doctor Evil
Knock a bit off if you're using stored energy. Then adjust the flow rate you use.
If you had a combi/stored system, you are unlikely to use the same 4lpm dribble that you would use in an electric shower. 10lpm might be more reasonable.
Then, the actual cost per time will actually get quite close to the electric. OTOH, the shower is so much better, that it gets the job done in half the time, although you may find, instead, that it is so much better that you stay in twice the time...
Christian.
Since I detect a rather patronising tone, I must be a pedant and insist that you are wrong. :-)
The amount of energy required to heat a volume of water depends on the temperature of the water and the pressure. Thus 4186 J/Kg/K for water is at standard temperature and pressure or STP as we used to write at school. (273K ish, 1 atmosphere).
I might add that water takes a lot of heating, which is something to do with the bond geometry. Thus I suggest we start showering in liquids that need less energy to heat.
Markus.
Personally, I think the higher the pressure of the shower, the longer I am likely to stay in there. It's more fun than if you have a dribble.
Like why do you need a one hour massage? Won't 5 minutes do? :-)
M.
Actually a bit older, but bit of a reprobate, got a U grade o'level. Oh the joy of hindsight, its the one thing i wish i'd paid more attention in
Can I guess you're over 65 and/or did economics at school? :-)
Regards Jeff
LOL - a man after my own heart
Regards Jeff
Don't do cheap....... do quality (triton t100) but wish i'd gone for thermostatic control ;-)
Regards Jeff
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.