WHY OUR SYSTEM?
Unlike other solar water heaters our drainback design eliminates overheating which contributes greatly to scaling and sediment buildup. In addition it has freeze protection and does not require periodic glycol (antifreeze) changes which can cost from $75 to $100 every 3 to 4 years. Our system includes a stainless steel heat exchanger that is not only higher performing than a copper heat exchanger but it is also easier to clean possible scale buildup.
The most important components of our system are from Europe. The collector absorber and glass is from Germany, the stainless steel heat exchanger is from Sweden and the ball valves are from Italy. We are Texas’ largest solar water system distributor and only buy the best.
Solar water heating is not just about durability and performance but since the system is also openly occupying at least a 7′ x 7′ section of the roof, aesthetics is very important. Techsun’s collectors are the most visually pleasing collectors on the market. With no visible piping around the collector and solar prismatic glass they appear as a skylight on the roof.
OTHER HOT WATER SYSTEMS
ICS, Batch or Non-active Systems
ICS or Batch system resellers claim that their “low cost” systems are simple with no moving parts.
What they do not tell you;
Only Hawaii and a few other locations are recommended for these systems. Misinformation and over generalizing of system performance has allowed these systems to be sold in other areas of the country. Why go through the trouble and cost of a solar installation and only get 40% to 50% efficiency (U.S.’s new tax credit is only for systems with 50% or higher efficiency)?
Closed Loop Glycol (Antifreeze) Systems
The primary disadvantages of glycol or antifreeze systems are the expense of changing the glycol every 3 to 5 years and a lack of over heating protection for the solar storage tank. Not only does someone have to change the system’s glycol every few years but the system must be re-pressurized and done properly so as to prevent air bubbles in the collector loop. This is not something the average consumer is equipped to accomplish so a solar professional is usually called upon and the cost can range from $75 to $200 for each refill. This additional periodic charge lowers the system’ financial return.
The primary problem with antifreeze systems involves over heating within the storage tank during the summer months. As long as the collector sensor is 10-15 degrees hotter than the tank sensor the system will continue to circulate the antifreeze (it must keep circulating or the glycol will breakdown during stagnation). There is no high temperature limit control for the water heater tanks and during the summer months the tank can reach almost boiling temperatures. This greatly increases scaling, tank sediment, corrosion and additional stress on the circulating pump and other system components. The initial cost for a glycol system is the same or more than our drainback system but the added cost of periodic glycol changes and overheating headaches accrued over the system’s lifespan make this system not as cost effective.
One Size Fits All – Single Tank Systems
The problem with many single tank systems is that one tank size does not fit any home. The department of energy rightfully claims that an average American consumes around 19 gallons of hot water daily with most of that amount being a hot shower.
Single solar system tanks usually have one active heating element 1/3 from the top of the tank (see image at left). This is to provide the consumer with backup heat during days of little sunshine. If there are three or more system users a single 80 gallon tank system will not provide enough hot water (30% of 80 gallons is only 24 gallons).
We recommend either two tanks or a single 120 gallon tank with the top element activated for homes with 3 or 4 occupants. A single 80 gallon tank can be utilized if there are two or less occupants and they are aware of their limited backup hot water capabilities.
If the backup heat source is gas or heating oil then only a two tank system is possible since the back up tank is being heated from the bottom .
Vacuum Tube Systems
The reason someone buys a solar water heating system is to save money and reduce pollution. The primary characteristics of choosing one system over another is as the Florida Solar Energy Center suggests; “Find a durable certified system which provides the best value for the total amount of BTUs (energy).” Vacuum tube collectors cost 30% or more than flat plate collectors and in most regions of the U.S. are actually less or equal in effeciency. The average consumer (and some solar installers) confuse it’s ability to reach higher temperatures (160+ degrees) with overall effeciency at reaching domestic hot water temperatures (125 to 140 degrees).
Vacuum collectors are typically only utilized with glycol systems. During an average U.S. summer day a vacuum collector glycol system can reach very high temperatures. This can cause premature scaling and sediment buildup, possible pump failure and tempering valve leaks. Aside from paying more dollars per BTU and dealing with high tank temperatures they do not appear as a skylight on the roof. Another issue with vacuum tubes is that even most of the better manufactured tubes will start losing their vacuum after 5+ years (most manufacturers do not cover long term vacuum loss as part of their collector warranties).
Tankless or On Demand Water Heaters
Tankless or on-demand water heaters are probably one of the most over hyped products on the market. Many distributors of these units claim that the consumer will have up to 60% savings. This is a completely ridiculous statement. These types of claims prompted the government to do a thorough study to determine their realistic performance. What they found was not surprising… an electric model saves 8 to 15% and a gas model (natural gas costs 1/2 as much as electric to heat water) saves 10 to 25% pending hot water use. See the actual report at (www.nrel.gov/docs/fy03osti/32922.pdf ). According to the NREL study and the Oct ’08 Consumer Reports a quality tankless heater with installation ($1,000+) the payback is around 20+ years.
In addition according to the manufacturers (and we couldn’t agree more) if the unit is placed in a scaling environment it should be periodically flushed with an acidic solution. The warranty for these systems do not cover scale buildup problems! Keep in mind that contrary to a traditional gas water heater these systems blast heat small copper tubes… a scaling nightmare. Just a slither of scale buildup on the exchanger piping will quickly errode any of the 10 to 25% savings. The electric units are actually illegal in many cities due to their extreme voltage surge. The installation cost is usually very expensive in that the electric units require very large breakers (50 amps plus) and the gas units require special venting and possibly a larger incoming gas pipe.
Aside from the above issues they do take less space and provide endless hot water (3-6 gallons per minute). They can be used in conjunction with a solar system as long as the tankless system has a sensor to determine the incoming water temperature.
Most experienced professional plumbers recommend the SETS, Rennai or Takagi systems.