subject: Know The Ins And Outs Of Solar Heating Systems Before Buying [print this page] If evacuated tube panel is the heart of your solar heater then solar heat exchanger is the brain to bring the real function to work. Their types existing in any solar heating system also affects the design you are choosing. As a laymen customer its impossible to go such depth of enquiry so you depend totally on your supplier for the system. If you are lucky to meet a reputed one, you would never find problem with your system else would be suffering every year especially at the freezing or hail times of the year.
So here are some very important basics required to know about such systems:
1: Firstly you need to know about the parts which consist of collectors, storage tank, and heat transfer medium, interconnected plumbing. There are two types of systems active and passive, open and closed.
2: Active system is the one that involves the usage of solar circulator pumps for the heat to move .Closed one is which does not require a pump and works on natural process of conduction, radiation and convection for the heat movement.
3: An open system does not involve the usage of heat exchanger and has open collectors but a closed system separates the liquid into storage tank where heat exchangers are located.
Now the question arise which one is better. Most of the places where electricity is really a hard thing to get, passive systems are preferred as closed system with controllers, pumps and valves require electricity to work. With an open system chances of water to get frozen into ice is pretty much compared to the closed one. The ice could tear the collectors and would allow leakage.
Now when it comes to design of such systems:
1.Integral/ storage tank system: The water is collected in the tank and is exposed directly to the sun for heating.
2. Thermo siphon: The heated fluid moves to and fro between the collector and storage tank. An open thermo siphon system does not work well with freezing temperatures. Although anti freeze valves can be a help here but it requires much of maintenance.
3: Drain back system: Has a non-pressurized tank and the panels are refilled by the pumps when suns warmth is detected.
4: Recirculation system: Designed for anti freeze function wherein hot water is re-circulated back to panels to make system acquire ambient temperatures.
5: Active closed loop: The most modern type wherein a non toxic antifreeze liquid like glycol is used.
