Any solar water heater system uses heat exchangers so that solar energy can be transfered and absorbed, only to be used in order to heat water or heat space. Different materials are used for heat exchangers including copper, bronze, steel, stainless steel, aluminum or cast iron. In most cases copper is utilized as it is a really good thermal conductor. It will also provide good levels of corrosion resistance. Now let us analyze some heat exchangers that are common and you might want to use.
There are basically two types of heat exchangers: liquid to liquid and air to liquid. One liquid to liquid water exchanger for solar heater systems will utilize heat transfer fluid. It basically circulates through solar collectors, absorbs heat and goes through heat exchangers so that heat is transferred towards the water in the storage tank. A number of heat transfer fluids will protect the collectors from freezing. One liquid to liquid exchanger system needs at least one barrier so that it stays effective. Any heat exchanger constructed through a system based on 1 wall will have a tube or a pipe that is always surrounded by fluid. A double wall exchanger will have 2 fluids and walls between them.
In order to have higher safety you should think about installing solar water systems based on double walls. The problem is that their efficiency is not as big when compared to single systems. All air to liquid systems will include the use of air heater collectors. They do not usually need the use of a heat exchanger to be used between air distribution systems and solar collectors. The two exchanger systems stand out as being highly similar besides the fact that one uses air and the other liquid.
Whenever you build a solar water heating heat exchange system there is a need to analyze sizing. If you want all to be really effective one important factor is size. When you analyze the subject you have to look at heat transfer fluid, temperatures in inlet and outlet, flow rates and the type of heat exchanger that you use. In most situations the manufacturer will offer you heat exchanger ratings to consult. Read all the specifications in order to make the best possible decisions.