Heat Exchangers for Solar Thermal Systems
Solar thermal installations use liquid-to-liquid heat exchangers exclusively: on one side, there's the solar fluid that travels from the collector; on the other there's the water being heated.
Solar thermal installations use liquid-to-liquid heat exchangers exclusively: on one side, there's the solar fluid that travels from the collector; on the other there's the water being heated.
The pumps used in solar thermal installations come in both AC and DC models. It is important to choose a model that not only fits your electrical supply but which is also compatible with the rest of the system, in terms of construction materials.
It's important to make one thing very clear when discussing piping materials for a solar thermal installation: copper or stainless steel are currently the only sensible choices.
It may be tempting to try to use a flexible material like rubber or Pex, but it won't work: there's a very good chance you'll have to replace all your piping within the first year of operation because it simply cannot withstand the constantly high operating temperatures of the system.
The problem with pipe insulation is that solar thermal systems operate at extremely high temperatures, all the time. You can forget most types of plastic and rubber insulation immediately, because they'll just melt off.
Solar energy is free, renewable and non-polluting, so why isn't it used everywhere today? Most people have the same implementation questions: Do you have to change your lifestyle with a passive solar system? Are there concerns with its variability and is it worthwhile? Are you better off going with a traditional heating system? Solar-based living does not necessarily mean a house full of glass and complicated electronics. There are some simple guidelines that will enable your home to enjoy the sun's energy to the fullest.
Most people are aware of using solar heating for hot water supply in the home. This is because about one third of our home energy bill goes towards hot water heating, as Florida State's electrical utility companies confirm. It is the third highest cost, following heating and cooling.
A solar water heater can operate together with your current electric or fossil-fuel water heater to supply a portion of the home's total hot water heating requirement. This will reduce greenhouse gas emissions, air pollutants and the cost of your water heating.
You can find plenty of water heating systems using solar energy today, including home-built designs that are simple but effective, like the batch heater. This design has no outer jacket or insulation blanket but is painted black and placed in an insulated plywood box. There is a plastic or glass glazing covering the assembly, which is angled to solar south. Pressurized domestic water goes into the tank’s bottom and heated water comes out from the top to your home’s hot water heater.
When your system is installed and operating, you can monitor its performance through the storage tank temperature and the heat exchanger’s inlet and outlet temperature difference. Tiny, slow leaks are tell-tale signs of poor performance and can be monitored on the pressure gauge. When the temperature of the circulation fluid changes, the system pressure rises and falls but the average pressure at rest should be the same throughout.