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Hot water heating system efficient for residential and commercial use 

With all the concerns raised in recent times about national security and energy, and the reliance on foreign sources for oil and gas, there is a very bright light on the horizon – in fact, we wake up to it each morning. 

Solar power, both electrical power and solar heat, can do a great deal to reduce our reliance on traditional sources of energy in all kinds of emergencies, from man-made to natural disasters.  

According to the University of Central Florida’s Solar Energy Center, “... We import more than 50 percent of the petroleum products that we need to meet these demands (for energy) from foreign lands. Interruptions to our fuel supplies cause havoc within our economy… and threaten our national security.” 

Diversifying our energy sources through solar energy can reduce our reliance on fossil fuels, and creates more reliable energy in all types of emergencies. Solar and other renewable energy sources have the potential to stabilize our economy as well, since production and transportation costs will be less reliant on fluctuating energy prices and availability. 

The simplest, most cost-effective way to capture and use the sun’s energy is through a solar hot water collector, used in conjunction with your existing hot water heating system. A solar hot water heating system generally consists of tanks or panels mounted on the southern side of a roof, unshaded by trees or buildings.  

Water is piped up to a tank or collector, allowing the sun to heat it. The collector may be a simple tank painted black, or may be a more sophisticated (and therefore more efficient) flat plate collector, where the water is run through a series of black metal tubes. Since more surface area of the water is exposed to the sun, the water is heated faster.  

The top-of-the-line solar hot water systems are the flat plate evacuated tube systems. These have tubing mounted inside a vacuum space. The vacuum acts as insulation, reducing the amount of heat lost. These are the most efficient systems, reducing the amount of energy needed to heat water in a single family home to near zero in summer, and substantially lowering it even in winter – the amount will depend on the quantity of water used and the weather, and of course the size of the system. 

Once the sun heats the water, it is circulated back into the building’s water heating system. In a passive system, this is achieved naturally as the warm water rises and flows into the storage tank. This system has no moving parts. 

In an active system, a sensor determines when the water is warm enough to be pumped into the system. If the temperature is high enough, solar-warmed water is pumped into your regular water tank as the hot water is drawn down at the tap. Some systems are equipped with a small solar panel that works when the sun is out, warming the water. The water is sent to an insulated storage tank for later use. 

These systems can be used in both residential and commercial applications for hot tap water and for heating (if your building has a hot water heating system), and should be individually sized to meet the needs of the user. The size will depend on the number of residents, the number of appliances that use hot water, and the existing system. Conservation measures include using low-flow showerheads and aerators, and water-efficient appliances such as front-loading clothes washers and efficient dishwashers. The more efficient your home, the smaller (and less expensive) your system will be. 

Solar hot water heaters have no moving parts (although some systems have electric pumps as previously noted), and have a reputation for being very reliable as a whole, requiring minimal work to maintain the system. Residential systems can range from $3,500 to $6,000 installed.  

The payback period is affected by a number of factors, but in general is between eight and 12 years. Most systems are designed to last more than 20 years, and in fact Berkeley has several that are still functioning perfectly after more than 25 years. 

Just choosing a solar water heater with good ratings is not enough, though. These systems require a plumbing permit and licensed plumber to install. You may also need some structural work done if your roof or other location is not strong enough to support the weight of the size tank you require. Additionally, since Berkeley is subject to occasional freezes, the system should have proper insulation for any exposed pipe or point where water could freeze and expand, and rupture the system.  

Proper design, sizing, installation, and maintenance are critical to ensure efficient system performance. Consult a licensed professional for the right system for your needs, and make sure all work is properly inspected. 

If your area is frequented with winter frosts and freezes, you may want to consider a closed-loop system, where an antifreeze-type of liquid is circulated via pumps into a water storage tank. This will preheat your water without exposing it to freezing temperatures. 

If your system is properly sized, and remains undamaged through a seismic event, you could actually have hot or at least warm water available to you during an emergency. In the event of another period of unregulated soaring gas prices, it will prevent those tremendously high energy bills from emptying your bank account. Solar hot water is reliable and inexpensive all year round. 

For more information on solar hot water systems, visit the U.S. government Web site for Energy Efficiency and Renewable Energy Network at http://www.eren.doe.gov/erec/factsheets/watheath.html, as well as the University of Central Florida’s Solar Energy Center at http://www.fsec. ucf.edu/index.htm. You may also want to visit the Berkeley Energy Office’s web pages at http://www.ci.Berkeley. ca.us/energy. For permit information, contact Berkeley’s Permit Service Center at 2120 Milvia St., at the corner of Milvia and Center Street, or telephone: 883-6555. 

The next columns will discuss the basics of solar energy, generating your own electricity, and either storing it for emergency use, or selling your extra electricity back to your utility. 

Alice La Pierre is an energy analyst for the city of Berkeley. The Daily Planet runs Power Play on the first and third Tuesday of the month as a public service.