Naked Science Forum
Non Life Sciences => Technology => Topic started by: thedoc on 16/09/2014 01:30:01
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David Gregory Kerr asked the Naked Scientists:
Would it be possible to replace the conventional heating element of a power shower with a coil of narrow bore copper pipe wound around a steel mandrel which is encased inside the stell cylinder which the mandrel fits inside of former made from varnished cardboard wrapped with 1,000 turns of enameled copper wire which connects to a high frequency bridge circuit which is driven by a 250KHZ veriable frequency oscillator which would allow the unit to run on just 5 watts of power at 250 volts which can be got from a three pin plug.
What do you think?
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Yes, but if it only takes 5 watts of electrical power it will only deliver 5 watts of heat (minus all the inefficiencies of the inverter). If you want to wash with flowing water at 2 liters/minute you need about 3,000 watts to raise the incoming water (at say 20 deg C) to 40 degrees. The best way to achieve that is with an immersed resistive heater, which is about 99% efficient at coverting electrical energy into useful heat (you lose about 1% heating the incoming wires) - i.e. an ordinary power shower.
Best of all, immerse yourself in a well insulated bath (say a styrofoam coffin) with a tiny amount of water, and wait until the 200 watts of your body heat has raised the water temperature to about 30 degrees, then apply soap. No electrical power, minimal waste water - the ultimate ecobath!
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It works as advertised but I found my well water is much colder in winter so now I am having to install a booster on the output side to get shower-worthy hot water. Be sure to check your incoming water temperature in a worst-case scenario (dead of winter) before ordering. This website have nice charts to help you decide on which model. Installation was simple and easy. I measured the current draw on my 240V lines and it was 61.5 amps. It should save me money over the old 50-gal tank unit it replaced. I am awaiting my next electric bill to see.
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Check that electricity meter! 61.5 amp = 14.7 kilowatts - about as much as an electric cooker in a restaurant!
If your well water isn't frozen, you shouldn't need more than 3 kW for a shower.
Most economical, though it costs more to install, is an air-source heat pump feeding a 50 degree storage tank. This will supply all the hot water you need for a small house, including baths and showers, at about one third of the cost of direct resistive heating.
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Just for interest's sake, many years ago (when the UK had a substantial engineering industry) I worked for a company which made moulding machines (presses) for the plastics industry. This company was almost unique in using induction heated platens to heat the press tools (moulds). These induction heaters were powered directly by the 50 Hertz mains current. As I recall, they were rated at up to, something like 20KW, and compared to resistive heaters produced a very even temperature tolerance across the heated area.
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I hope one day, these great British engineers will awake again and make Britain a bigger and brighter place again.
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Just as soon as we get out of the crooked EU, my friend.
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Just as soon as we get out of the crooked EU, my friend.
As soon as we get our of the EU, you will discover that the conservation of energy isn't EU legislation and the OP's idea still won't work.
On the other hand, nor will your 3KW shower.
If your well water isn't frozen, you shouldn't need more than 3 kW for a shower.
The commercial ones all run about 3 times that - 8 to 11 KW
https://www.plumbworld.co.uk/search?q=electric+shower
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I hope one day, these great British engineers will awake again and make Britain a bigger and brighter place again.
Sadly the demise of the great British engineers was bought about by the attitude of the establishment in the UK, that financial services etc., were far preferable to engineering industries.
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I hope one day, these great British engineers will awake again and make Britain a bigger and brighter place again.
Sadly the demise of the great British engineers was bought about by the attitude of the establishment in the UK, that financial services etc., were far preferable to engineering industries.
Actually it's more interesting than that.
Teh figures here
https://en.wikipedia.org/wiki/Economy_of_the_United_Kingdom#Manufacturing
show that the manufacturing industry is (or was in 2011) more important to the UK economy than the finance industry.
"In 2011 the UK manufacturing sector generated approximately £140,539 million in gross value added "
"The UK financial services industry added gross value of £116,363 million to the UK economy in 2011."
It's just that the Tories have been lying about the need to preserve the finance sector- not because of its importance to the UK, but because a lot of yuppies vote Tory.
The Brexit will hit both industrial sectors hard.
It looks like the single biggest direct cost will be the £40 billion settlement that the brexiteers forgot to write on the side of a bus.
There will be other massive damage like this
https://www.newstatesman.com/politics/staggers/2017/11/loss-european-medicines-agency-due-brexit-could-hinder-access-life-saving
which will probably kill people, as well as costing the UK about half a billion pounds in lost revenue.
Apparently that's worthwhile price to pay for "taking back control"- a phrase which seems to mean "abandoning any pretence at control and handing the reins of power straight to Brussels."
The finance industry in the UK is more likely to be wrecked by the decision to move the European Banking Authority to Paris.
https://www.theguardian.com/politics/2017/nov/20/london-loses-european-medicines-agency-amsterdam-brexit-relocation
And, when all is said and done, the OP's idea still won't work; and I think we should make this clear- not even if we use British engineers. :o
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The Brexit will hit both industrial sectors hard.It looks like the single biggest direct cost will be the £40 billion settlement that the brexiteers forgot to write on the side of a bus.There will be other massive damage like thishttps://www.newstatesman.com/politics/staggers/2017/11/loss-european-medicines-agency-due-brexit-could-hinder-access-life-savingwhich will probably kill people, as well as costing the UK about half a billion pounds in lost revenue.Apparently that's worthwhile price to pay for "taking back control"- a phrase which seems to mean "abandoning any pretence at control and handing the reins of power straight to Brussels."The finance industry in the UK is more likely to be wrecked by the decision to move the European Banking Authority to Paris.
Yes, Brexiteers are happy to leave the EU, AT ANY PRICE!!. It's all about ideology, and memories of the days when Great Britain still had an empire. Sadly, expecting that our exit from the EU will result in the reappearance of the Great British engineer seems to be the pinnacle of misplaced optimism.
Your links are informative, thanks, but is it not still the case that present-day UK engineering companies (as well as previously state-owned utilities) are predominantly owned by overseas interests?