Solar Thermal - Open System(Direct) or closed?

EcoSupply

Hi,

I found two different solar thermal solutions as follows but how do I decide which one is best. Will the greener homes grant be available for both? The open system looks good as I will not have to change my exisiting single coil 140litre cylinder.

Descriptions
An Open System heats your hot water directly. I.E., cold water is channelled into the roof, heated directly by your solar energy, brought down through the remainder of your heating system and finally out through say, your shower or taps. As such, fresh water is continuously brought into an open system, and hot water leaves it directly.

A Closed SolarLink System heats your hot water indirectly. I.E., water is circulated up to your roof and heated by solar energy in the same way it would in an open system but with one crucial difference - the hot water that circulates inside a closed system never leaves it. Its sole function is to indirectly heat fresh water through a coil inside a hot water cylinder.

Can anyone help me out on this one?

Thanks

MickLimk

Closed system, no question!

EcoSupply

Thanks MickLimk, Why do you think closed system is better? Please find information below on open system - taken from a UK website.

"Very simply put, a 'direct evacuated tubes' heating systems gives better performance (40% than traditional solar panel collectors (anti freeze style), because you are heating the actual water up. No heat transfer loss here. Evacuated tubes are proven to be most efficient, but 'direct' solar tube technology, has improved this efficiency even further. "

CJhaughey

Freezing, corrosion and limescale are problems with direct water circulation.
There is a company in the North that makes a product called a solasyphon that allows a normal cylinder to be used with a solar thermal setup.
I don't know anything about the product apart from the fact that it is made in NI and can be used for this purpose.