Home » General Health » The Development of Solar Hot Water Systems

This method is the standard for hydronic heating systems and many industrial heat transfer tasks. Naturally, they applied this design to solar systems, treating the collectors as the boiler and the tank as the receiver. If you walk into most professional engineering firms and ask them to design you a hydronic heating system OR a solar system, they will grab their manuals that show how to assemble a pressurized glycol loop.

Since it is too expensive to fill the solar storage tank with a glycol solution, the heat is transferred from the collector loop into the tank through a heat exchanger. The collector fluid goes through one side of the exchanger and the tank water goes through the other side. It is like the rope caulking used in boat hulls for thousands of years. As long as the boat stays in the water, all is fine. If you take it out and let the caulking dry out, it will leak until the caulking gets soaked again. There are many other kinds of automatic air vents, some based on the float system seen in toilets.

Since pressure goes up and down with temperature, a clever system was devised to maintain a nominal pressure in the loop. A tank, called an expansion tank, is installed in a tee in the line. The expansion tank has a rubber membrane running across the middle. The system fluid fills up one side and air fills the other side. The fluid in the system can expand and contract with temperature into the expansion tank, and the air bladder will keep the pressure within a specified range. The air pressure is set with an air hose and tire inflator, just like a car tire. A chart is used to determine the correct pressure according to the temperature of the system at the time. However, expansion tanks have a lifetime.

A solar RO Water System Guys, on the other hand, has the boiler sitting outside in the weather. It is always off at night where there is no sun. In the summer time, the solar hot water system will see its maximum temperature, which varies according to the application. The most extreme case occurs when there is a very hot day with high solar radiation, and there is little need for the hot water. This can occur randomly on weekends, or summer vacations, and especially on space heating systems that sit idle all summer. When this scenario happens, the heat from the collectors is not needed and the temperature builds up until the boiling point is reached.

The system stops working, compounding the problem, and needs to be attended to. This is a progressive failure mode. The pump should never stop running during the day on a glycol system in warm weather. To avoid the over temperature problem, large glycol systems have additional equipment installed to dump excess heat. It usually consists of a big fan coil unit in the collector loop that kicks in when the temperature gets too high and dumps the heat to the outside world. The components include temperature controls, bypass valves, fans, and pumps.

The added complexity just adds more failure modes. Heat dump systems cannot overcome power failures, unless you add a back up generator, which can have its own failure modes. At night in the winter when the collectors are cold, the cold glycol solution will try to circulate naturally down the supply line, creating a thermal convection loop. Some systems have even frozen the heat exchanger in this manner, causing rupture of the cold water line. A check valve must be installed in the collector supply line to prevent fluid from flowing backwards under cold conditions.

Published at: Recent Health Articleshttp://recenthealtharticles.org

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