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Solar Hot Water System

With hot water solar heating panels that heat a copper cylinder with no pump, to an internal heating coil, does the "flow" from the solar heating panel run to the top of the coil in the copper cylinder or the bottom, bearing in mind that with a gravity system hot water rises?

Z.

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  • I will not be heating the whole house, just producing limited hot water for washing and shaving.

    www.ebay.co.uk/.../254011629563

    Doesn't look ideal for gravity flow - you'd have to orientate it on a steep slope with the connections high & low (not both at the same level) - and then those small contorted channels look like they'll provide quite a resistance to the flow (and being horizontal not ideal for gravity circulation).

    The old school way was to take a cheap ordinary radiator, paint it matt black and stick a sheet of glass in front of it (the posh ones were put in a wooden box with some rockwool insulation behind to reduce losses). They can be quite effective - I managed to scald myself with a homemade one when I was about 11.

    you need a hot fire to get much sense out of a gravity fired heating system

    Temperature often isn't a problem with solar - or rather one of the major challenges is controlling high temperatures. With the system I've got at home (vacuum tubes) not only are plastic pipes on the solar circuit a complete no-no, but soldered copper isn't acceptable either - the stagnation temperature of the panel can exceed the melting point of plumbers solder! So it's copper and compression fittings only (alternatively flexible stainless steel pipe). If it's not open vented then you need some way of dealing with excess pressure if the pump fails - some systems rely on the water in the panel itself flashing to steam and pushing the rest of the water content away from the heat source - so oversized (as well as heat resisting) expansion vessels are the normal (as well as pressure relief values).

       - Andy.

  • I may experiment with one of these.....

    Solar Pod Swimming Pool Heater | eBay

    Z.

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