DIY solar heating

[Bob Mannix]

A couple of years ago, I couldn't find DIY solar water heating kits (you could build your own manky system Blue Peter style, giving the satisfaction of true DIY but little else, I fancy, or pay someone a huge amount to install one).

Having revisited the scene I find kits are now available eg:

taking this as an example, a DIY kit, with a simple plumbing arrangement (for those of us with tanks!), with an additional pv panel to drive the pump, is £1900.

I would surmise savings in the region £100-200/year (guess) giving a payback time of 10+years.

Does anyone have experience of such kits, with regard to savings, and this kit in particular, with regard to its quality?

[Mike]

satisfaction

I haven't experience of it myself as I'm building my own "Blue Peter" one :-) I certainly liked the pv panel for the pump and have copied this.

A while ago somebody on the

forum gave the Solartwin one the tumbs up over others. Try having a search on google for the thread.

[Nick Finnigan]

about 1000 kWhr a year, which is reasonable. They only suggest £100 a year saving in exceptional circumstances.

[Mark]

Er But that costs £1.9k, my Blue Peter DIY one cost £

[John Stumbles]

I doubt you'd save that much: we're paying c. £40 a month i.e. £480 pa on gas for our 3-bed semi, of which most is likely to be space heating. If 1/4 of that is water heating of which perhpas half could be supplied by solar then we'd save £60 pa.

Only at 0% interest rates :-)

If you borrowed at 5% interest to install it you'd be paying £95 on the loan in the 1st year (decreasing as the loan is paid off) so taking into acount the lifetime of the solar system you'd quite lilely never make anything back on it. (And if you had the money to hand already you'd have to compare with what you could get investing it in a long-term savings account.)

Technically, the solartwin system also constrains you to an open vented system with a hot water cylinder (or more expense putting in heat stores etc) so when you come to replace your CH boiler (with a shiny new condensing one) you can't easily go for a combi.

[Bob Mannix]

It was time rather than money/ingenuity but I guess a "manky system Blue Peter" comment deserved a snotty response from someone who had built one that works :o). I had already decided it was too expensive but wanted others comments. At least I was asking the question!

Could you furnish any diagrams on your system? The commercial one referred to did have the advantage of being (almost) entirely non-invasive to the existing system.

Cheers,

[Bob Mannix]

This is very true.

/duck hooray! duck/

I guess it's Blue Peter route (see other response) or nothing then.

Cheers,

[bigcat]

Excessively expensive. Doesnt have a hope in hell of paying back.

Solar heating can payback very well indeed, but only if you design it right. I have never seen a commerical system that I would describe as desgiedn right.

For some odd reason, most solar engineers live in a world where cost and payback are complete non issues. This problem has dogged solar energy all along.

There is a good ng for this, alt.solar thermal.

Solar HW is quite tough to make pay; it can be done, but most systems dont achieve it.

Solar flat panel space heating OTOH captures vastly more heat, costs less to install, is simple to blue peter, and has excellant payback figures as long as you design it sensibly, which is easy compared to DHW heating.

Theres another good payer: a crossflow heat exchanger on the shower. Warm water going down the drain heats the cold supply to the shower, result is you use much less hot water. Payback can be under a year, depends on level of use.

NT

[raden]

In message , Mark writes

You'd better post some details then

[John Stumbles]

And passive solar design of newbuild (or occasionally retrofit) can be even better vfm. (When we went to Ladakh one little beacon of optimism against the rather depressing tide of inappropriate 1st-world model 'development' of that delightful 'subsistence economy' was Helena Norberg-Hodge's version of our CAT who were promoting such small-scale appropriate technologies as trombe wall solar heating which could achieve remarkable increases in comfort in buildings for the price of a modest amount of glass and wood. (See about halfway down:

[bigcat]

The Victorians put a lot more thought into this area of building design

- sometimes. Trouble with this sort of thing is its not a universal plug in, it requires understadning and design skills to work out how to do it and when. And today competition on basis of cost is pretty harsh, and rules out such unnecessary skilled input in nearly all new builds.

The publishing of a set of standard proven designs, along with checklists for each to see when you can use them, plus payback figures etc, could change this. But I've not seen such a thing anywhere.

Regrettably solar seems to be the domain of those with insufficient awareness of real world finances.

The fact is that among the sea of unlikelies, there are some solar designs that pay back excellantly. It seems only a matter of time before more widespread awareness occurs - though it doesnt seem to have got anywhere yet.

NT

[Mike]

Totally agree but big problem here is most BCOs throw a wobbly at such an installation as it is beyond their experience. They 'understand' drainage and don't like thinks out of the ordinary.

[Mike]

Yep - the foyer of the Alexander palace is a fine example of when they got it right.

Pity about some other parts of the building :-)

[stejonda]

In message , [e-mail] writes

Are such crossflow heat exchangers easily available? I've searched via Google but could only find air-venting ones.

[Mark]

Well ive got a few things going in my favour, I live on the south coast and in a very sheltered valley the house having had many alterations over the years has a roof ideally suited being a u shaped /\_/\ Theirs nothing special about the design, it's the same as the conventional example shown on

but all the parts were obtained from boot sales or farm auctions, Its got 4x 6ft radiators in a wooden frame with Perspex covers sited in the V of the roof facing S-SW. Pump is 12v and powered by elec solar panel 1x1m, the only mod I had to do was the pump motor stalled when Volts dropped below 5v, (which also meant that there wasn't sufficient heat/light either) fixed with 2 Zener's and relay. We use a LOT of hot water during the summer (three B+B rooms) and hot water is by oil boiler so every 1degree saved is worth while IF the initial outlay is modest. Winter I don't care as we have a HUGE wood burning stove. HTH

-- Mark

[IMM]

The US government were on the verge of introducing large scale solar research. A report stated most of the US energy needs could come from solar....in 1952. It was dropped for the Atoms for Peace garbage. Again a major report indicated the same in 1980. In the final days of Carter he stared the ball rolling. Regan scrapped it and even took the solar panels off the White House roof. Bush has suppressed any notion of large scale solar research.

So in the USA vote Democrat not oil company lackeys Republican. Similar here, but on a smaller scale. The Tories pander to big oil, while Labour have an effective wind power generation project under way and increased home insulation levels, and are still increasing them, to levels we though only Sweden would do.

[bigcat]

I'm not familiar with anyone selling them yet, it would likely be a diy job. But its not very difficult.

You'd need 2-3 ft of copper drain sized pipe, some microbore, and solder. Wrap microbore round the big copper pipe, but rather than one piece, use 4 in parallel. Solder them in place. Use a 4 way manifold at each end of the microbores, so the cold water flow goes thru the 4 in parallel.

The cold supply for the shower goes into the microbores at the drain end of the thing, and comes out at the plughole end, going to the shower.

It cuts right back on energy use, and makes your tank of HW last substantialy longer. Payback varies according to use, but maybe a year or so, that sort of region.

NT

[Mike]

Wouldn't the ones that both Andy and IMM recommended above a heat bank work ?

[bigcat]

Fraid I dont know what youre referring to there.

Bear in mind the shower waste goes through it, so the shape needs to be conducive to free flow, roddable, not pool, and be fittable to the shower waste piping. ie a bit of pipe would be ideal.

NT

[Mike]

Why does shower waste need to be roddable ?