Variable refrigerant flow (VRF) systems are really no different than more traditional HVAC systems when it comes down to good installation practices.
. If a system is not installed correctly, then it doesn’t work properly, and it will not reach its maximum energy-efficiency potential. VRF systems require the same level of care and quality work as ducted HVAC systems, maybe even slightly more.
Dominic Freschi, owner, Freschi Service Experts, Antioch, California, has been in business since 1980. His company was purchased by Service Experts in 1996 and, since then, he has expanded to include VRF, among other things. VRF systems, while extremely energy efficient and beneficial in certain applications, have a weak link, said Freschi.
“Maintaining the purity inside the copper piping and ensuring the integrity of the piping is crucial. Otherwise, you’re going to have nothing but problems with your system,” he said. “Remember, these are refrigerant-based systems. If you have a leaky water pipe on a boiler system, chances are it’s not going to shut down the performance of the unit. But if you have a leaky refrigerant line, it could disrupt the complete performance of the entire [VRF] system.”
In fact, Freschi has been called in to fix plenty of installation errors on VRF applications including a recent case where a technician left a gauge in the system.
“The business got fed up with the company that installed the system. They couldn’t find the problem, so we were called in,” he explained. “We went in and found the problem. Somebody left a gauge in the system, stuffed up in the ceiling area. Nobody could find it. It shouldn’t be just any Tom, Dick, or Harry installing these systems. Techs need to be properly certified to install this equipment.”
“Good installation practices actually minimize callbacks and extend the equipment’s life span,” said Brian Drummond, director, B-DACS Air Conditioning Services, Glasgow, Scotland, U.K. “On more than one occasion, we have been asked to go back in and rectify a poor installation by other contractors — whether it is leaking water from insulation breaks; poor drainage installations; undercharged systems; poorly installed, incorrect pipe sizes; incorrect cable types; or squint fan coil units.”
Drummond commonly encounters incorrectly addressed equipment such as the installation of fan coil units in server rooms. “This is never a good practice, and we would always suggest a single-split system suitable for the duty of the server room,” he said. “If VRF has multiple fan coil units and goes into fault mode, the server room goes down also. Clients don’t normally mind employees overheating, but they don’t like their computers overheating. Some contractors deliberately undersize systems to make their tender quotation very competitive. If the correct cooling duty has not been selected correctly, this can be very damaging.”
Training is Key
Rod Cory, VRF product specialist and training developer, Trane, a brand of Ingersoll Rand, said about 15-20 percent of all previously installed VRF jobs were done to manufacturer specifications. “This number is on the rise as more manufacturers mandate training prior to an install,” he explained.
“Proper installation is paramount to a positive outcome. VRF operates by means of logic, and nearly every VRF manufacturer has screens throughout the refrigeration circuit before and after major components. A clean, dry, and tight system is a must.
“Each VRF manufacturer has design software that must be used during the design and installation phases,” he continued. “The software will provide pipe sizes throughout the piping network, the additional refrigerant needed to assure a proper charge for that particular job, and it will flag the designer or installer if piping rules have been broken.”
According to Cory, contractors need to understand that VRF requires special training, special tools, and the ability to operate a computer. “Training is key. You cannot discount knowledge or the importance of following manufacturer recommendations,” he said.
Follow the Instructions
Rick Boucher, commercial service specialist, Goodco Mechanical Inc., State College, Pennsylvania, said contractors need to be aware of manufacturers’ requirements, as each has its own instructions.
“The installers need to read the installation manuals,” he said. “Standard refrigeration practices need to be adhered to as they are absolutely critical to a system’s operation and efficiency. Pressure testing, evacuation, nitrogen flowing, mounting, clearances, etc., all need to be done to the factory standards. When they are not followed, the system may underperform — especially on extreme hot or cold days.”
Communication also plays an important role during the installation process.
“Follow the manufacturer’s piping schematic that was provided,” Boucher said. “Do not follow the pipe size on the building plans. If any piping changes need to be made, consult the engineer who produced the schematics to confirm if any other changes need to be made. It is always a good idea to remain in contact with the engineer throughout the installation. They have seen it all. Our distributor, Comfort Supply Inc. in Pittsburgh, is very knowledgeable and able to help us through our installations and provides professional training at its Living Lab. Maintain communication with your distributor throughout the installation process. Develop them as a resource because they are your best source of information and knowledge.”
When installing VRF systems, Boucher advises contractors preplan and walk the job site prior to the installation; follow the manufacturer’s schematic, noting and communicating any necessary changes; record all liquid line sizes during installation; follow R-410A piping and flaring procedures; follow refrigeration best practices; follow twining-kit installation instructions; and put a VRF-trained installer in charge of the installation process.
Do it Right the First Time
Steve Niezur, director of sales and engineering, Comfort Engineering Solutions LLC, a division of Young Supply Co., Chesterfield, Michigan, said his company tries to eliminate problems associated with cutting corners on job sites by having tech advisors and sales engineers visit job sites throughout the installation process. This helps ensure the proper techniques are being used and to try to anticipate problems before they happen.
“People tend to cut corners, and I hate to use that term, but they try to save on costs by not doing everything that should be done in order to ensure the installation is done the way they were taught,” Niezur said. “The extra manpower we have on hand is an extra overhead cost, but to be able to visit job sites on a regular basis to make sure everything’s being done properly is an investment we’re willing to make to avoid any costly mistakes after everything’s installed, drywalled, and painted over.”
Comfort Engineering Solutions was formed five years ago because of the growing popularity of VRF in the U.S. The company installed a complete training center at its location in Farmington, Michigan, and is a Mitsubishi Electric-authorized training center. It holds two to three classes a month from September to May.
“We allow noncompetitors to send people from out of state to attend our classes if they need to get certified,” Niezur said. “And, if a contractor takes this three-day service installation class, it allows him or her to get an extended parts warranty above and beyond the standard warranty that comes with this equipment. Plus, we’re more apt to sell a VRF system to someone who’s gone through the training versus someone who just wants to come in and buy it. We’ve actually refused sales because we know there could be possible problems down the line. We just don’t want to get involved with that.”
Dennis Kurzawa, solutions specialist, Young Supply Co., said: “Product knowledge is the key element. If you know how it operates, how it’s supposed to be put in, and how it’s installed, that eliminates a lot of the trouble projects. Generally, most of the problems we see are just simple stuff, but these can cause problems with the system.”
“VRF is taking off, but there are precautions you have to take to apply, design, and install it correctly,” Niezur said. “If it’s all done correctly, you can expect a 25-year life expectancy out of this product.”