Single-panel radiator as solar water heater...

[Ian Stirling]

Insulated/glazed?

[IMM]

a book on how to make the panels (also sell a kit too) and how to make the differential controller with component parts, diagram, etc.

[IMM]

As would plastic pipe. Makes mainly don't want the pipes near high temps, like boilers. So make not be the right pipe as summer solar temps make get near boiling.

[Mark]

They're glazed with acrylic sheet on a wooden frame. This is no high tec installation though, it was basically thrown together with bits I had to hand or had picked up at farm/boot sales, total cost was not much more then the copper pipe and antifreeze used. The hardest part to replace would be the pump, no idea what it came from originally, but a very nice stainless casing/impeller with 3/4 ins in/outlets driven by a small 12v motor, possibly something medical. its got

3M Sterivac on a lable.

[N. Thornton]

This is a common approach and works fairly well, but is not the best efficiency wise. With such a system sometimes the pump can run when the panel is cooler than the tank. A proper diff stat woudl give you a bit more heat output.

Regards, NT

[N. Thornton]

Yeah, I like that, though I foresee problems. You'd need to use marine polystyrene, as most is not closed cell, and water logs. The other thing is if youre going to rely on being able to freeze the rad, you need to be sure the beads are in every section of the rad. And I would expect they would jam here and there and not fill all areas of the thing. Result: rad splits when it freezes.

I think I'd sooner go for either a drain down system, or one that warms a cold water tank feeding the bath cold tap and shower, thus enabling the existing HW to be used much less for a given amount of warm bath or shower.

Dont forget to use a waste water heat exchanger on the bath too: the payback figs for those are impressive.

Regards, NT

[Steve Firth]

Glass beads. Commonly used in chemical plant, very cheap and would last forever in this application.

[Grimly Curmudgeon]

It was somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "IMM" saying something like:

Syntax error. Auto fault self report feedback defective.

[nick smith]

application.

EH ? I thought glass was not very compressible - so how does this work then or is it a troll again,.,.,,., Nick

[Steve Firth]

It's not.

It takes up space in the radiator and reduces the volume of water.

FFS are you scared of your own shadow as well?

Hint: frost proofing wasn't the be all and end all of the suggestion.

[IMM]

forever in this

You are right, it isn't.

Alas a Troll.

[nick smith]

Thought so (knew so!) - another one for the kill file - plonk !

Nick

[N. Thornton]

in this

Glass beads dont have substantially less thermal capacity than water, nor are they compressible.

Regards, NT

[Steve Firth]

Well duh, glass has a thermal capacity (SHC) 0.84 that of water, and polystyrene has a thermal capacity (SHC) of 13. So errm, glass has a thermal capacity significantly less than that of water and polystyrene right at the other end of the scale. Somehow I don't think you meant to type the above. At least I hope you didn't.

Only relevant if your suggestion had any merit.

And your suggestion isn't going to work. If one fills the radiator with compressible polystyrene beads, they will, unsurprisingly migrate and compress as the water is pumped. Again this effect is well known to those who design various bits of chemical equipment because we often need to immobilise reactants on a substrate. Sometimes you have no choice but to use a compressible substrate and then one finds that the pumping speeds that can be used are extremely limited. Pump too fast and the compressible medium will compress and obstruct flow.

And of course since we intend to use this medium in a hot liquid, hopefully well over 60C, polystyrene is a pretty poor choice since it will soften.

And of course you can't get closed cell polystyrene balls, or ballotini.

I suggested glass beads because they are inert, rigid, available in a wide range of sizes, and cheap. The specific heat capacity of the beads is a red herring, since they won't be going anywhere, so the heat absorbed by the beads is a constant. It gives a small amount of thermal lag in the system, and that's it. However they do greatly reduce the volume of water in the system and will lead to faster warm up times than if larger volumes of water were to circulate through the channels.

The notion of frost protection by using compressible beads is IMO a bloody non-starter because you won't be able to get beads with the characteristics required.

[TP]

Fill these fins with expanding foam and place at the rear of the cabinet. Face the other side towards the sun and paint it black.

[alan_m]

Only 18 years too late for the reply!

[Brian Gaff]

Yes would be interesting to see if its still in use after that time. Brian

[steve]

absolutley

[Andrew]

absolutely 18 years too late to reply.

[chop]

Only 18 YEARS late, stupid.