In our previous article we discussed and expounded on Drainback Systems plus the pros and cons of such a system. Our focus shifts to Open Loop Solar water heating system.
Open Loop Systems
Open loop means that the water that requires heating flows directly through the hot water solar collector itself. There is no intermediary fluid.
Open Loop Systems are suitable for single application domestic hot water (DHW) systems, in mild and moderate climates where there is no risk of freezing.
Pumps circulate household water through the collectors and into the home. They work well in climates where it rarely freezes.
Recirculation systems are a specific type of open-loop system that provide freeze protection. They use the system pump to circulate warm water from storage tanks through collectors and exposed piping when temperatures approach freezing.
In an open loop (direct) system, the solar collector is separate from the storage cylinder, and the water from the cylinder that is being heated for consumption circulates through the collector panel by natural thermo-siphon (open loop) or by pump. A system such as a temperature controlled pump to allow hot water to be circulated through the panel on cold nights to prevent freezing must be integrated into the circuit.
Advantages of Open Loop
It is the simplest and typically the least expensive active system to install. There is no heat exchanger, which allows efficient heat transfer directly to the water. The system operates at standard line pressure. It is simple to add capacity to the system if demand changes. The system integrates easily with existing systems.
Disadvantages Open Loop
Some stored heat can be lost when the system re-irculates. It does, however recirculate from the colder bottom of the tank and supply pipes, and there are minimal losses in the loop and none through the collector. The primary freeze protection needs electricity or battery back-up.
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| Basic Open Loop System |
Open Loop Systems
Open loop means that the water that requires heating flows directly through the hot water solar collector itself. There is no intermediary fluid.
Pumps circulate household water through the collectors and into the home. They work well in climates where it rarely freezes.
Recirculation systems are a specific type of open-loop system that provide freeze protection. They use the system pump to circulate warm water from storage tanks through collectors and exposed piping when temperatures approach freezing.
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| Further Illustration Of This System |
Advantages of Open Loop
It is the simplest and typically the least expensive active system to install. There is no heat exchanger, which allows efficient heat transfer directly to the water. The system operates at standard line pressure. It is simple to add capacity to the system if demand changes. The system integrates easily with existing systems.
Disadvantages Open Loop
Some stored heat can be lost when the system re-irculates. It does, however recirculate from the colder bottom of the tank and supply pipes, and there are minimal losses in the loop and none through the collector. The primary freeze protection needs electricity or battery back-up.
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