Solar heat exchangers

A solar heat exchanger is a component used in an active solar water heating system to store energy from the sun and heat water for sinks, showers, or wherever hot water is needed. The exchanger is usually made of copper, a good thermal conductor with better resistance to corrosion than other metals.

How a typical exchanger works is:

rays from the sun heat a solar collector on the roof of the building
temperature sensors feel the temperature of the water in the storage tank is lower than that in the collector
a controller turns on a pump to move the storage tank water to the collector to get heated and return to the tank until the a set maximum tank temperature has been reached
the pump turns off
cold water is piped through a copper heat exchanger submerged inside the storage tank. When a hot water faucet is turned on, the cold water goes through the heat exchanger, the tank's stored heat is transferred to the cold water and it comes out of the faucet hot
as the storage tank water temperature falls, the pump moves the water up to the collectors to get reheated

The advantages of using a solar heat exchanger instead of a traditional hot water heater are:

major cost savings on electric or gas bills, usually by 50 to 80 percent, since the electricity needed by the pump is very small
maintenance cost and inconvenience are nearly eliminated since solar heat exchangers seldom need repair
solar heat exchangers reduce environmental impact, using minimal fossil fuels to operate, emitting no toxic chemicals, and needing replacement much less often
there are multiple tax incentives and grants available for installing solar heat exchangers. The federal government provides a 30 percent income tax rebate for the cost of a solar installation. The state of North Carolina allows a 35 percent state tax credit. South Carolina has a 25 percent state tax credit and a $1,000 state rebate. For commercial installations, depreciation will provide up to an additional 15 percent of the system cost. There is also the USDA Renewable Energy for America Program (REAP) grant for businesses that use 250 gallons or more of daytime hot water and are in a community of less than 50,000 people. For a complete list of all state solar incentives, visit the Department of Energy's Database of State Incentives for Renewables & Efficiency (DSIRE) website.

Three common designs of heat exchangers used in solar water heating systems are coil-in-tank, a coil of tubing in the storage tank or wrapped around the outside and covered with insulation; tube-in-tube, the tubes of water and the heat-transfer fluid directly touch each other and flow in opposite directions; and shell-and-tube where the heat exchanger is outside the storage tank and contains two loops of fluid inside a shell. The potable water flows in one loop opposite in direction to the heat-transfer fluid in the second loop. The transfer fluid flows between the shell and the tubes of water.

Investing in a solar hot water system adds to property value in addition to helping solve the global energy and climate change issues. The payback time decreases as energy prices continue to rise. A small system can lower your utility cost and increase your energy use awareness. Watch the attached video on the installation of a Heliodyne solar water heating system.

A sample cost is Solar Direct has a sale price for a solar water heater 65 gallon system with a 4' x 8' solar collector installed at $2,129 until March 31, 2013. See the website for details.

In the Greenville, South Carolina area, contact these companies for information and quotes:

Four Seasons Home Improvement, 864.268.0564, 117 E. Woodburn Dr., Taylors, SC 29687

R & C Construction Solar, 864.561.7314, 888.748.9165,132 Bascom CT, Greer, SC 29650

NetZero USA of Greenville, South Carolina, 115 Industrial Drive, Greenville, SC 29607

Sunstore Solar Energy Solutions, 864.297.677, 63090 South Highway 14, Greer, SC 29650

Southern Energy Management, 864.631.2828, 1120 West Butler Road, Greenville, SC 29607

Addison Homes, LLC, 864.848.2667, 12 Parkway Commons Way Greer, SC 29650

Gear Solar, 864.879.0600, 866.999.0975, 1861 South Highway 14, Greer, SC 29650

Hurst Energy, 926 NE Main St., Suite F-144, Simpsonville, SC 29681

SUN Banks Solar, 864.220.7051, 202 Siloam Road, Easley, SC 29642

Carolina Solar, PO Box 67, Campobello, SC 29322

Zimmer America Solar Power, 864.463.4352, 800.458.3194, P.O. Box 5561, Spartanburg, SC 29304