Water Well Journal
Issue link: http://read.dmtmag.com/i/629532
"You need good, clean power," Williams says. "I prefer to use a diesel generator because the power is nice and clean and they're consistent. I also use a pretty good sized one, so I'm actually over-powered most of the time." A consistent flow rate is also important. To ensure a consis- tent flow rate, you should make sure all of the air is purged out of the unit before starting the test. "It's basically the last thing you do before you engage the heating elements and inject heat into the loops," Henrich says. "If you don't have all of the air out, you can cause a flow rate to change or have inconsistent flow throughout the test which again get into that consistency when you're trying to pump the heat in." Properly insulating your setup is always important but is especially critical in the heat of summer or in areas with harsh winters. "We've seen tests where people have not insulated the pip- ing where it comes out of the borehole into the units and it rains," Henrich recalls. "The rainwater just running down the side of the loops saps a lot of the energy, and you'll notice the temperature creep level off while it's raining." Keeping everything covered and insulated helps keep the temperature curve consistent. Adding more insulation by cov- ering the unit with concrete blankets or other specialized insu- lating blankets also can keep the highs and lows out of your data stream. During the test, Williams performs real-time monitoring where he can look at actual temperatures and make sure his data profiles are good. "When I get to the end of that test I've got even more con- fidence," he maintains. "That's because I've had some hands- on during that 48-hour period of time." After collecting the data, you're looking for slope stability and temperature stability during the data collection to make sure there's not a lot of highs and lows or aberrations in your data. You can also compare your data to the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) standards, which is the criteria used in the United States to determine acceptable data. If there were problems with the data collection, let the unit sit long enough for the temperatures to reset in the earth, probably five to seven days, and retest. "Pay attention when you're doing the testing," Williams in- sists. "You want to be sure your unit is performing properly and you don't have any hiccups or issues that could question the test." Also, don't be afraid to learn more with more research. "If you're going to do thermal conductivity testing, be curious and learn a little more about it," Henrich suggests. "Become a little more well-rounded. There's several different methods of doing thermal conductivity testing and data analy- sis, and learning more about those gives you a better under- standing of why we're doing a test." By making sure you have stable power, consistent flow rate, and proper insulation—you can be sure your system is well designed. And won't need "geo janitorial" work after the fact. WWJ Know How Hydrogeology Can Impact Large Systems Understanding Hydrogeology and Its Impact on Large-Scale Geothermal Heat Pump Systems bridges the gap between existing HVAC literature and geothermal heat pump (GHP) industry training. They provide a useful reference for those involved in planning a large-scale GHP project. Learn more in the NGWA Bookstore at www.NGWA.org. Know Industry Guidelines Get the Guidelines for the Construction of Loop Wells for Vertical Closed Loop Ground Source Heat Pump Systems. This third edition is written for loop well contractors, loop well design consultants, government officials, educators, students, and consumers. It's a stand-alone source that doesn't supersede regulations or standards and provides details on issues related to constructing vertical closed loop ground source heat pump systems. Visit the NGWA Bookstore at www.NGWA.org for more information. Twitter @WaterWellJournl WWJ February 2016 23 Jennifer Strawn was the associate editor of Water Well Journal from 2004 to 2007. She is currently in the internal communications department at Nationwide in Columbus, Ohio. She can be reached at strawnj2 @gmail.com.