Hi,

Just been discussing this with one of the guys at work and was wondering if anyone had used one of these as an outside solar water heater, you know painted matt black and mounted on the roof. I think it would work very well, especially if the side not facing the sun was insulated with foam.

That you think, would two this size give enough heat for normal hot water in a house?

For the winter when its not doing any heating anyway, I suppose it could be isolated and then drained dry to protect it from icing up inside.

You could even have an inline thermostat that only let water flow once it was at a certain temp so that at night the hot water stored would not be lost.



[Edited on 11/1/10 by Mr Whippy]

Didn't Dick Strawbridge do something with a rad and solar heating, on one of those "Its Not Easy Being Green" programmes he did?

You should put it in a box with a "window" to stop convection.. (rad's are rather good at this)..

I'd get a scrap rad and make a test one to see how well it might work before going to to much hassle..

Dan

I know someone that has done it, and it has provided trouble free hot water for them for the last 25 years, they live in Scarborough.

They have two on a south facing roof, inside a picture frame affair with perspex covers. the rads are painted black,with insulated silver reflectors to the rear.

I suppose it depends on your location, and how much hot water you use. Although an immersion heater back up could be fitted.

Antifreeze would stop it freezing in winter.

The only problem they have is if they go away in the summer, the neighbours have to come in and run off the hot water now and again.


Al.




Originally posted by Mr Whippy
Hi,

Just been discussing this with one of the guys at work and was wondering if anyone had used one of these as an outside solar water heater, you know painted matt black and mounted on the roof. I think it would work very well, especially if the side not facing the sun was insulated with foam.

That you think, would two this size give enough heat for normal hot water in a house?

For the winter when its not doing any heating anyway, I suppose it could be isolated and then drained dry to protect it from icing up inside.

Tbh I had thought of just putting them in the back garden (like you suggest in a box with a Perspex window) and running two buried insulated 22mm plastic pipes into the house and into the hot water tank under the stairs. There's an embankment at the back that faces south and with the panels on the ground they'd be able to use convection for circulation rather than a pump.

black panel collectors are the cheap but less effective option but they still work. They need to be kept in a sealed glazed box to keep the warm air next to the collector from mixing with the cold air outside. Most systems work by having a dual coil hot water tank and circulating antifreeze through the collector and one of the coils. That way, the hot water never goes through the collector.

The cheap way is to let the antifreeze thermo syphon round the loop. It is not as effective as a pumped system. Pumped systems have a temperature sensor on the outlet of the collector and in the hot water tank. When the collector temperature is more than the tank, the pump is switched on. If the collector cools, the pump is switched off.

They work on sunlight not heat so will work in the winter when it is cold. Except there is less sunlight in the winter. Make the collector big enough and you should have all the hot water you need for large parts of the year.

If you size your system right, on a sunny summer day, you'll have a full tank of piping hot water by mid afternoon. In the winter, you'll get a small rise in the temperature of your water tank during the day then when your boiler switches on in the evening, it has less work to do than if you didn't have solar heating. On a snowy day when no light hits the panel, your boiler will have to heat the water from cold.

thanks for that, looks very simple and cheap to setup unlike most of the green ideas this looks like it would quickly pay for itself

I'm currently building some DIY, very locost, evacuated tube phase change heat exchangers for this very purpose.

I even have a parabolic mirrored trough to focus the light, locost of course

Watch this space. I'll do a write up when I'm done.

[Edited on 11/1/10 by liam.mccaffrey]

We have a double solar-panel approximately 2-3 times the size of the radiator shown in the pic. Works in conjunction with a special dual-cylinder.

A good sunny day (we face Due-South) just about provides enough hot water to keep me and Mrs Scootz happy!

[img][/img]

Lol... that lump of snow in the pic just came crashing down and scared the hell out of the neighbours cat!

Solartwin keep pestering me about this (cos I inquired about it once) and their systems works with the normal system you have. In the winter it still works but the pump slows down so you still have hot water you'd just be relying on the gas a little more. If you get it working well post the plans on here

quote:

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Originally posted by smart51

Pumped systems have a temperature sensor on the outlet of the collector and in the hot water tank. When the collector temperature is more than the tank, the pump is switched on. If the collector cools, the pump is switched off.

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Looks interesting, Id like to see the ROI timeframe?

I saw on one of those scam builders programs that the ROI could be about 50 years or something stupid...

quote:

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Originally posted by liam.mccaffrey
I'm currently building some DIY, very locost, evacuated tube phase change heat exchangers for this very purpose.

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