Tools Check Validity of Being Green

July 28, 2008
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Thermal imagers, such as Fluke’s TiR, make it easy to spot unexpected temperature differences within buildings, which can indicate unnecessary wasted energy and building efficiency issues. (Courtesy of Fluke.)


Green buildings typically incorporate environmentally friendly products that conserve natural resources, save energy and water, or are made from recycled materials. These types of products are usually tested by manufacturers and independent agencies to make sure they contribute positively to an efficient green building design.

For HVACR contractors, though, it is a little more difficult to discern whether a heating, cooling, or ventilating system is adhering to green building guidelines.

This is why specific tools are often needed when working on these types of structures. These tools can range from the usual - manometers and gauges - to the unique - thermal imaging and balometers.

ENSURING PEAK EFFICIENCY

Green building is all about energy efficiency and to make sure customers are receiving the efficiencies they’ve paid for, technicians need to ensure air conditioning systems are operating at peak efficiency. Rey Harju, president, Fieldpiece Instruments Inc., noted that studies have shown that air conditioners typically run at capacities of 8-22 percent less than those for which they were designed, reducing their EER by 4-16 percent.

“Potentially, this means that many newer models are operating no better than older, lower SEER-rated models operating at their peak efficiency (which is also rare). In fact, a recent National Comfort Institute study suggests that 57 percent of air conditioners in operation today are running below maximum efficiency,” said Harju.

All too often, a technician may simply glance at line pressures to see if a system is operating, but that does not give any indication of efficiency. And as long as customers feel cool air coming out the vents, they may not ask too many questions about optimizing efficiency, which is key in green buildings. By not using the correct tools to ensure system performance, a technician is setting himself up for callbacks and irritated customers.

Most air conditioning problems are related to refrigerant charge and airflow. Too much refrigerant charge can shorten the life of a compressor and too little reduces efficiency, even to the point of no cool air coming out after a few days. Both problems can result in callbacks by angry customers.

The Fluke AirMeter® allows technicians to measure and calculate all components of airflow, including pressure, humidity, and temperature. (Courtesy of Fluke.)

Fieldpiece’s products make it easier to properly charge an air conditioner using superheat and subcooling, said Harju. “Our relative humidity accessory head takes the measurements needed to enable a technician to calculate the target superheat or subcooling. And we have another standalone instrument that will automatically take measurements and calculate the target superheat. Our superheat and subcooling accessory head enables the technician to take the measurements, make calculations, and display the actual superheat and subcooling. The technician determines whether to add or subtract refrigerant based on the difference between target and actual.”

After using these tools to optimize efficiency, the technician needs to check the evaporator exit temperature, said Harju. If the temperature is too low or too high, it can cause problems similar to having too much or too little refrigerant. If it’s too low, the airflow needs to be increased, and if it’s too high, the technician needs to check for issues such as fan speeds that are too high and dirty condensers.

Harju stated that Fieldpiece’s HG1 HVAC Guide guided probe Tester can make a technician’s job easier by combining superheat, subcooling, and target evaporator exit temperature.

“It guides the technician, step-by-step, to performing these tests. It displays an input form that the user fills out by attaching the appropriate accessory head, taking the measurement, and automatically inserting the reading on the appropriate line of the input form. Once the form is filled out, the user presses the output button to display the output form. All the calculations are made and displayed.”

With the Fieldpiece HVAC Guide™ Tester in-hand, a technician checks for airflow and capacity problems with the target evaporator exit temperature (delta T or temp. split) switch position. (Courtesy of Fieldpiece Instruments.)

DOCUMENTATION AND ACCURACY

Green building designers place great emphasis on long-term efficiency and sustainability, and some green certification standards have heavy documentation requirements (including measurement accuracy and trending over time) to verify that efficiency. Test tools for these applications need to have high accuracy and repeatability, to provide the same measurement each time, without variance, as well as the ability to log and download data.

To meet these demands, Fluke offers a wide variety of test instruments, which include multi-function air meters, as well as stand-alone CO meters, temperature-humidity meters, particle counters, thermal imagers, and power loggers. “For airflow, Fluke meters make it very easy to measure and calculate all components of airflow, including pressure, humidity, temperature, and outside air percentage - but knowing where to take the measurements to get comprehensive results relies on the contractor,” said Chris Rayburn, indoor air diagnostics product marketing manager, Fluke Corp.

The big advancement with airflow meters is having one tool that takes multiple measurements semi-automatically, noted Rayburn. Previously, contractors used multiple tools with mostly manual calculations, with a much higher potential for error. In addition to measuring velocity, these new tools allow users to enter duct information, capture multiple samples, and automatically calculate airflow.

The technician wets and clips a thermocouple on the return air filter (above) then seals the panel to measure indoor wet bulb with a diagnostic psychrometer (below). (Photos courtesy of Fieldpiece Instruments.)

Thermal imagers are also helpful in a green contractor’s toolbox, as these make it very easy to spot unexpected temperature differences within buildings, which can indicate unnecessary wasted energy and building efficiency issues. “Fluke’s TiR thermal imager is exponentially easier to use than any previously available model on the market, and its features are optimized for work in building environments,” said Michael Stuart, senior product marketing manager, Fluke Thermography.

In buildings designed green from the ground up, a thermal imager helps determine if green building construction techniques and practices are, in fact, actually working. In green building retrofits, a thermal imager is indispensable for detecting hot and cold air leakage in the building envelope from bad seals, gaps around windows and doors, or improper structural insulation, or due to improperly insulated or installed HVAC equipment and ductwork, noted Stuart.

A relatively new instrument for some HVAC contractors may be a power data-logging tool, which is used for conducting energy studies and determining basic power quality logging.

A power logger measures most electrical power parameters, harmonics, and voltage events and logs the information, which can be transferred to a computer for analysis and documentation. The tools can be used for energy assessments, which quantify energy consumption - a very important aspect in green buildings.

“This is a new skill to many facilities contractors and slightly more complicated than the average electrical maintenance task,” said Frank Healy, power quality product marketing manager, Fluke. “Moderate-to-highly skilled technicians have reported strong success with adopting power logging tools, as their customers become more sensitive to changes in energy consumption.”

Contractors specializing in green building techniques will need to familiarize themselves with many new tools, which include those mentioned earlier, as well as flow hoods, ultrasonic gauges, and equipment that tests levels of light and formaldehyde. Fortunately, tool manufacturers are responding to these green needs by providing new instruments that allows HVAC professionals to perform their jobs better, safer, faster, and easier.

Publication date: 07/28/2008

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