By M. Power |
11/29/2009
Here’s a new twist on the pros and cons of vented attic spaces—a product that captures heat generated by a hot roof, as it exits the ridge vent. To my knowledge, the
Greenward Ridge Vent is the only product on the market of this type.
Kevin Scott, president of Energy Alternatives in Manchester, Conn., says the product is about to enter the marketplace, as soon as five preliminary test installations are complete.
“We partnered with Benjamin Obdyke, since they already make a ridge vent,” Scott explains. “For the thermal transfer, we have 3/8” PEX tubing, with customized hangars. We’ve designed it so they don’t impede airflow from the soffits.
“This is a no-pressure system,” he adds. And the PEX has been tested for 200 F. Plus, its indirect heat transfer. I don’t see it ever getting close to that hot, but we have a relief valve in place in any case.”
How efficient is the system? Scott says it’s designed meet the needs of a family of four, saving 60% to 75% of daily water heating costs when solar radiation is optimal.
That’s roughly equivalent to 12 million BTUs per year.
“A higher attic will tend to be more efficient,” he adds, “but it’s not a huge difference if the attic is more shallow. The payback works out to under five years, and a system can be installed, for under $4,000, once you include the 30% federal tax credit.”
The Greenward will be marketed in the Southeast and Southwest first, Scott says. “The other thing we’re doing is offering the system without the tank as a pre-install,” he notes. “The builder has to put in a ridge vent anyway. This way he can say, ‘Here’s a home that’s solar hot water ready.’”—M. Power
Specs
FEATURED PRODUCT Greenward Ridge Vent System
Manufacturer Energy Alternatives
Mixture Water and Glycol
tubing PEX (rated to 200 F)
Valves SharkBite
Temp. Differential Goldline (shuts off pump when attic is cool)
pump Grundfos (2 gal./minute)
storage 80 gal. stone insulated
Vaughn tank
system Cost (retail) $3,099