Thanks for explaining the arithmetic. I have often thought that it should be possible to have a small US-style hydro station at Teddington Lock near me,, but following your numbers 800m litres/day (avg) x 2.68m drop is just 258kW. It just seems amazing that so much could produce so little, especially since this assumes 100% efficiency. I guess head is everything.
You can get small low head turbines but you phenomenal amounts of water to get any decent power from them. Water supply is normally the hard bit so the higher the head the more you get per kg of water passing through the turbine.
Well it's the product of head and flow. The "Barrage du Rance" (or whetever the frogs call it) across the Rance estuary in northern France produces substantial power form very little head and massive volumes.
I think you could use a length of 42mm Cu pipe (which is totally compatible with BS 5454 push fit plastic waste). Around the out side of this (say 1m length) spiral four pieces of 8mm microbore and solder them in place, to make good thermal contact. Connect the four ends into a 22 4 x 8mm "manifold" fittings at each end of the spiral. then you have a reasonable waste water to pressured water heat exchanger. My guess is that the flow of an electric shower with this arrangement would probably settle out as double the flow rate without, or you could go to half power on the electric even in winter.
We've had this discussion some time back, the american device that is sold for this purpose is a short length of ~2" copper pipe in series with the drain, around this are wrapped 4 adjacent coils of microbore soldered to the drain pipe and joined into the cold water feed to the shower. The drain water forms a skin around the copper pipe and as such is a good heat eaxchange surace without fouling.
Last time I mentioned it it was more to boost a shower heat output than to save the planet.
The message from "Dave Liquorice" contains these words:
But lb to a pinch of salt the supply would be more constant than a windmill, cheaper to install and not visually objectionable like windmills.
Isn't the average output of those ridiculously sited London turbines of the same order of magnitude as 258kw.
We have of course had this argument before (2 years ago) and IIRC the minimum flow at Teddington is 600 million litres a day and the maximum 9 times that so there is some scope for higher outputs.
Agreed, there is a 700 odd kW hydro system near here, supplies roughly 50% of the power used on The Moor. I bet most people don't even know it's there, they probably walk past the generator "hall" thinking it's a double garage. The water supply pipes are buried from a restored reservoir near the fell top originally built to provide water for the water wheels in the lead processing plant. English fecking Nature almost put a stop to the project due to the "disturbance laying the pipes". You couldn't tell where they ran 18 months after installation...
Oh, indeed, but first you have to make enough money to stay alive.
House are essentially, in terms of stuff that works,rather than looks prety, prety bioring engineering systems. They are not deish=gend tomake yiu feel good emotionally, or salve yor green conscience, and nor should they be. They are there to offer you a warm dry spoace in which uou get all that guff from other thiungs.
I too, have owned several Jaguars.All I can say, is don't own a Jaguar if you are worried about what its costing you. It spoils the pleasure.
But at least there you are buying a thrill, performance and comfort.
With a roof top windmill, its ugly, expensive, uses more energy to make than it will ever pay back..you may extend your definition of benefit to cover other than cash terms. but what benefit is a windmill that doesn't generate electricity? you probably can't even paint it pretty colors and watch it occasionally go round.
That is actually not a bad idea. Better still, use a car radiator and suck air through it for ventilation..Mind you, you need a turd muncher to get rid of the lumps..
As the actress said to the bishop, stirring her tea ...
Water head has to be low power, cos they pump water into tanks from boreholes using windmills in many part of the world, and we all know how effing useless windmills are.
That's interesting -- I wasn't aware what the sizes were above 35mm.
My original thought was to take a couple of 28-15-28 T's*, ream out the end-stop on the 15 so you can push the pipe straight through, and make up a length of concentric pipe that way. The reason for incorporating it into the vertical part of a deep U-trap was to ensure the waste pipe side is completely full of slow flowing water for max heat transfer time and contact, rather than trickle of fast flow with a lower surface contact and short heat transfer time.
or 35-15-35 T's, until I saw the price, £35 instead of £2! A 42-28-42 T isn't bad though, at £5.
I've just started to read this thread (only recently back on line since my HD died before Christmas).
Why just grannies?
We're both grandparents - well, we would be! - and have never had heating on through the night. Recently he set the timer to have the heating come on just before getting up time, I hate that but men are such wimps ...
When the children were small we had no ch and we got up to a cold house unless the coal fire had been left on overnight. That was pure luxury. The fire had to be lit most winter mornings.
When they were teenagers we had gas fires in the downstairs rooms, that was lovely because we could have breakfast in a warm room.
Our ch is now governed by the thermostat (except for an hour in the morning). The boiler will fire up if the roomstat in the hall gets down to
10C but it rarely does.
I'd hate the gas bills of most people too. When we had a fall of snow recently I looked at other house roofs in the street, ours was the only one with a complete white covering (which was a little irritating since the solar panel was covered too). That meant that more heat was being wasted in other houses than in ours. Insulation is cheap and free for many, why don't people take advantage of it?
Oh - and despite being grandparents we're still fitter than most people half our age.
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