I have installed my evacuated tube solar panel and it's working well, picking up heat even in this weather. However I'm amazed at how warm the manifold remains after sunset; the manifold sensor will be showing around 20C at sunset and this will take several hours to drop to ambient temperature. This means that either:
1 - The manifold is incredibly well insulated and is holding the heat in the bulbs at the ends of the tubes and the copper manifold.
Or:
2 - Warmed water is back-flowing up through the coil into the manifold, which is about 6' vertically above the cylinder.
I plan to rejig some of the pipework soon and think I will install a valve to prevent backflow; I understand that I need a flap valve which I will put in a vertical position on the flow from the coil to prevent cold water from dropping back down into the coil.
The pump is a small plastic jobbie that is rated for a 2m head so I doubt if it will overcome the resistance of a standard anti-backflow valve. Can anybody point me in the direction of a 15mm flap valve that requires only the lightest pressure to operate?
1 - The manifold is incredibly well insulated and is holding the heat in the bulbs at the ends of the tubes and the copper manifold.
Or:
2 - Warmed water is back-flowing up through the coil into the manifold, which is about 6' vertically above the cylinder.
I plan to rejig some of the pipework soon and think I will install a valve to prevent backflow; I understand that I need a flap valve which I will put in a vertical position on the flow from the coil to prevent cold water from dropping back down into the coil.
The pump is a small plastic jobbie that is rated for a 2m head so I doubt if it will overcome the resistance of a standard anti-backflow valve. Can anybody point me in the direction of a 15mm flap valve that requires only the lightest pressure to operate?
