Solar water heating

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Mary Fisher" saying something like:

That he had a bath at all and that he could afford coal?

Reply to
Grimly Curmudgeon
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It isn't worth doing much to save 20 pounds per year, but it might make more sense to collect both hot water and space heat from a polytunnel, which might have a linear parabolic reflective north wall over a 2'x6'x8' shoebox tank with an EPDM or polyethylene film liner and a $60 1"x300' piece of pressurized polyethylene pipe for a heat exchanger and a horizontal draindown EPDM cover with a small pump to move water up 2" over the cover when the sun is shining, and a greywater heat exchanger, eg 2 55 gallon drums with PE pipe in series.

Gary Reysa and I have been working on this sort of DIY stuff. See

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Reply to
nicksanspam

The figures used in the SAP calculations where applicable are 50% during the heating season (taken as 34 weeks) and 50% during the rest of the year.

Reply to
Tony Bryer

The latest SAP 2005 algorithms for a 100m2 house, 110 litre factory insulated cylinder give a required raw energy input for DHW of

3172kWh. Divide this by the boiler efficiency to get the actual energy required.
Reply to
Tony Bryer

The figures in this thread have stated the savings amount required to make it worthwhile. If you think you can save well over £100 a year with a £2000 water heater, go for it. I dont.

I do.

Mary

NT

Reply to
Mary Fisher

We don't. When he does wash it he uses cold roof water from the butt.

Reply to
Mary Fisher

That it was a he and that coal was used in the house.

Reply to
Mary Fisher

would take - as said before - the remaining life of the universe to pay this off,

Don't be daft.

Reply to
Mary Fisher

It has changed the way we use hot water.

And it's turned us into thermoholics - watching the thermometer every time we pass!

Mary

Reply to
Mary Fisher

I know exactly what you mean. I have to check the voltage in the batteries every time I pass the meters, and peek at the windmill whenever I'm on the east side of the house.

As it is, now, I shower immediately before leaving for work in the morning - I expect once I get the solar heater in, it'll be more likely the first thing I do when I get home, in Winter at least.

Reply to
Derek Broughton

Yeah, I can calculate it too - I was checking if my numbers for cost/BTU were a reasonable average.

Reply to
Derek Broughton

On Wed, 08 Mar 2006 11:41:40 GMT someone who may be Tony Bryer wrote this:-

And the efficiency of the pump and pipework. I doubt if the conversion of gas into hot water is ever going to exceed 80% efficiency over a year. That gives 3965kWh gas input. At 3p per kWh that is 118.95 a year, at today's prices. A solar water heating system should save at least 75% of this through the year, which is £89.21 a year saved at today's prices.

If the water is heated by off-peak electricity, in theory 100% efficient, at 4p per unit, then 3172kWh cost £126.88 at today's prices.

I have no idea by how much the price of gas and electricity will go up by over say 20 years, but it will go up. The price of sunshine will remain the same though.

As for maintenance, an evacuated tube system may need a tube or two replacing over 20 years, but that will probably be it.

Reply to
David Hansen

On Wed, 8 Mar 2006 12:22:51 -0000 someone who may be "Mary Fisher" wrote this:-

In some ways changing attitudes to energy use is at least as important as anything else. The Sustainable Development Commission looked at the way local power sources change attitudes in

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from which the quote ?It seems that micro-generation provides a tangible hook to engage householders emotionally with the issue of energy use? Householders described the sheer pleasure of creation and of self-sufficiency: ?It?s like growing your own vegetables?? is a good one.

Reply to
David Hansen

The fifty US gallon figure I quoted, was not for HOT water - it was for ALL daily water use.

Reply to
S Viemeister

I couldn't have put it better!

Mary

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Reply to
Mary Fisher

I've been looking at one such system, but those glass tubes are fragile. I can't see them standing up to the frequent very heavy, occasional hurricane-force, winds I get here, so I'm going with a flat panel system.

Another problem, I've been told, is that efficiency of E.T. systems goes down when you get snow, as it collects between the tubes. Flat panel systems, it slides off. We usually get a lot of snow, though not this year.

YMMV. Obviously, not everybody has to worry about frequent extreme winds and snow.

Reply to
Derek Broughton

I know that's what you said. Nevertheless,

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says it IS what families use.

Reply to
Derek Broughton

According to

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the typical home uses 17% of their energy consumption on heating water. That would make it somewhere between $15 and $30 a month for most families. They also state on that page that "A family of four, each taking a five-minute shower a day, can cut water heating costs $250 a year by switching to a low-flow showerhead." Given that, I would have to say that the statement that you would only save 20 British Pounds a year ($34.73) a year to be completely ignorant of the actual facts.

Reply to
Ron Purvis

Good lord. None of the figures are cost of hot water.

The =A320 a year figure is proposed saving from a basic system, and will vary a fair bit IRL.

The =A3100 a year figure is how much a =A32000 system would need to save per annum to ever pay its way even if you made the most wildly optimistic assumptions.

NT

Reply to
meow2222

Good lord. None of the figures are cost of hot water.

The £20 a year figure is proposed saving from a basic system, and will vary a fair bit IRL.

The £100 a year figure is how much a £2000 system would need to save per annum to ever pay its way even if you made the most wildly optimistic assumptions.

What you don't seem to understand is that just because you made up a number, doesn't make it valid. Your number has no basis in reality.

Reply to
Ron Purvis

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