The Energy Column - Solar Water Heaters

The Energy Column 2002
Now in its 16^th year!
Written by: Ken Sheinkopf
Phone: 321-638-1007 Date: March 9, 2002
Fax: 321-638-1010 Column No.: 02-10
E-mail: sheinkopf@fsec.ucf.edu

Q.: "I’m interested in solar water heating for my home. Can you send me any plans to build a hot water system?"

A.: I really don’t recommend that you try to build your own solar water heater, though I have seen plans over the years aimed at do-it-yourselfers.

When you consider that the solar water heating industry has existed in the U.S. since the early 1890s and over the years the components and materials have been greatly improved, you can see why buying a system rather than making your own really is the best idea.

Today’s systems are tested and certified by state and national organizations. They are made by companies that, in most cases, have been around for many years. They are fairly inexpensive, especially when viewed on a life-cycle basis that usually pays back the full purchase price in around 5 to 8 years, depending on usage factors, and then continue to perform for many years beyond that. But most importantly, they have been proven to work, proven to save energy and proven to save you money over their lifetime.

If you really want to do the work yourself, it is easy these days to buy ready-made collectors and system kits from a number of companies that make these products available on their web sites. However, purchasing these materials is only one of the steps in getting a solar system. Maybe the most important step is to be sure that it is properly installed. This can make all the difference in the world. It is advisable that anyone wanting to do some of the work themselves buy the parts from a certified and reputable company and have the system installed by an experienced and licensed contractor. The best-made system in the world won’t work properly if it is not installed correctly.

The bottom line is that I’m not sure you would gain much by building your own system and I don’t recommend it.

Q.: "I have been trying to get information on central air conditioners. We live in Florida and use the air conditioner much of the year. People tell me about SEER but they can’t explain it. I was told to purchase a central A/C with the highest SEER but it is expensive. Is this true?"

A.: The Seasonal Energy Efficiency Ratio (SEER) is the way air conditioners are rated. The higher the SEER, the more efficient the unit. For example, an air conditioner with a SEER of 12 will be 20 percent more efficient than one with a SEER of 10.

I always recommend that homeowners buy the unit with the highest SEER that they can afford. Yes, the higher the SEER, the more expensive the air conditioner. But over the lifetime of the unit, you will save much more energy (and money) with the higher-rated unit, making it a better financial investment. In a climate like Florida’s, choosing an air conditioner that is as energy-efficient as possible is the most important factor in lowering your energy bills.

Since some of you like to know the technical details (skip this paragraph if you don’t), the SEER is calculated by taking the cooling provided by the unit (in Btus of energy) and dividing that by the electricity that is consumed (in kW).

There is one other thing you need to know before buying an air conditioner based on the SEER that complicates your purchase decision a little. This number only tells the unit’s efficiency. It has nothing to do with the ability of the unit to dehumidify the air. The ability of an air conditioner to dehumidify is expressed by its SHF (Sensible Heat Fraction) rating, and in this case, the lower the SHF, the better it will dehumidify.

Your job, then, is to get some estimates from contractors and look at the SEER and SHF of the systems they recommend. Pick one that offers the best combination of the two ratings. There is usually a trade-off here that you need to make, but comparing units based on these two numbers will help you pick the right one for your home.

 
Energy Note: A study from the U.S. Department of Energy found that consumers who use energy-efficient appliances in their home could save $200 in electricity and water bills each year. Clothes washers and dryers, dishwashers and other appliances that are energy efficient can save between 25 and 60 percent of the energy used by older appliances, as well as up to 67 percent of the water used. In fact, Secretary of Energy Spencer Abraham noted that if every American household had energy-efficient appliances, the water savings each year would equal the average flow of the Mississippi River into the Gulf of Mexico for five full days.