Home Improvement : Solar Heat Is Good for Roof and Wallet Too
QUESTION: An energy audit showed that hot water costs us almost $400 a year. Are there any types of hot water solar systems that do not look so bad on our roof? About how much would I save on my utility bills?
ANSWER: The amount of savings from a solar system is called “solar contribution.” You can size a solar system large enough to provide 100% of your hot water needs. However, the best payback is usually from a system sized to provide 50% to 60% (annual savings of $200 to $240).
There is a new type of shallow water heating solar collector that is designed to look like a skylight on your roof. It lies flush against your roof surface and is less than 2 1/2 inches deep.
Instead of using the standard copper tubes for the solar absorber plate, this system uses a black EPDM rubber absorber. This is energy efficient and does not have to be drained in areas where freezing is a problem.
Inside the very shallow collector, the EPDM absorber plate lies on closed cell foam insulation to minimize heat loss. Instead of using a glass cover, double insulated and ribbed clear polycarbonate plastic (bulletproof glass) is used. It is virtually unbreakable.
Using the plastic cover also offers automatic overheating protection. When the solar collector gets too hot, if the water flow stops, the plastic cover bows slightly from the heat. This opens small vent holes around the edge. When it cools down again, it straightens and they close.
Although your roof may not provide the optimum collector angle for highest efficiency, the lower cost of this type of collector makes it feasible. This also makes it an easy do-it-yourself job since mounting brackets and supports are not needed.
Another new type of solar collector system uses concentrating collectors. Although these are usually tilted up from the roof, they are smaller than standard flat plate collectors. They have a special sun-tracking sensor so they rotate to follow the sun throughout the day. The high concentrating temperatures can provide free and very pure distilled drinking water too.
If you have a sunny spot, you can install solar collectors at ground level. For heating water throughout the year, they should be tilted up from horizontal at an angle equal to your area’s latitude angle.
You can write to me at the address below for Utility Bills Update No. 227 showing a list of manufacturers of all types of water heating solar systems, and detailed information on the two new solar systems discussed above. Please include $1 and a self-addressed stamped business-size envelope.
How to Handle Foggy Double Pane Windows
Q: I have thermal double-pane windows in my house and several of them have gotten foggy. Is there any method to repair them myself? If I have to buy new panes, what type should I get?
A: It is difficult and hazardous to try to separate the glass panes yourself and to try to reseal them. There is also a moisture absorbing desiccant powder inside the windows to stop fogging. This must be dried out first.
You will probably have to replace the foggy glass panes. To ensure the proper fit, buy the glass from the original window manufacturer. Low-E, argon gas-filled glass will be the most efficient panes to fit the sash.
Letters and questions to Dulley, a Cincinnati-based engineering consultant, may be sent to James Dulley, Los Angeles Times, 6906 Royalgreen Drive, Cincinnati, Ohio 45244.
