วันพฤหัสบดีที่ 2 สิงหาคม พ.ศ. 2550

Solar water heaters # 2 Types of Solar Water Heaters

Types of Solar Water Heaters

Active Systems
Active systems use electric pumps, valves, and controllers to circulate water or other heat-transfer fluids through the collectors. They are usually more expensive than passive systems but are also more efficient. Active systems are usually easier to retrofit than passive systems because their storage tanks do not need to be installed above or close to the collectors. they will not function in a power outage.


Passive Systems
A passive solar water heating system, also called batch or breadbox collectors, uses natural convection or household water pressure to circulate water through a solar collector to a tank or to the point of use. A Passive System has no electric pumps. This makes them generally more reliable, easier to maintain, and possibly longer lasting than active systems.


"Open-Loop" or "Direct" Systems
The simplest solar water heating systems use potable household water, which is heated as it passes directly through the collector and then flows to the house to be used for bathing, laundry, etc. This design is known as an "open-loop" (or "direct") system. In areas where freezing temperatures are common, however, liquid collectors must drain the water from the collector when the temperature drops.

"Closed-Loop" or "Indirect" Systems
The circulating heat-transfer fluid flows through a heat exchanger, which heats the water to be used by the household. In closed loop systems the circulating fluid is an anti-freeze solution or refrigerant as opposed to water. In closed water systems the circulating fluid never comes into direct contact with the water used by the household. The alternative is an ‘Open Loop’ or ‘Direct’ Systems.

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Jack กล่าวว่า...

This is the most basic of pool heating. Minimal set up required and good results have been heard.
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