In today’s world where time is precious, doing the job right the first time is critical. Your customers want reliability and appreciate the attention to detail that will ensure their system provides cooling or heating when they want it. So how does one minimize the callbacks and warranty servicing on the units they installed or serviced? Using the best contamination control practices is a good starting point.
All HVACR technicians learn the basics when they go through technical school but many of us may have forgotten a few of the not so obvious steps. So, a quick refresher may help you improve the quality of your installations, increase your customer satisfaction and referrals that drive repeat business, growth, and the bottom line.
Good contamination control starts with the install
Keep out debris. There are many opportunities for dirt, solder, flux, copper chips, etc. to be introduced during the installation of the air-conditioning or refrigerating unit. Minimizing the introduction of solid materials is easy by covering the open connections to the system and ensuring tubing and components are free of chips, burrs, caps, etc.
Use flushing products correctly. Flush products can be used to clean the tubing and/or coils being reused to remove residual oil, wear particles, burnout residue, etc. Too often a technician will inject the cleaner and then let gravity drain the fluid to the collection device. Most flush systems recommend using pressurized air or nitrogen to blow out all of the liquid. If this step is not completed, much of the flush will remain in the tubing and will eventually evaporate but will leave behind all of the debris that would have been ejected.
Install a high performance filter-drier. Many of today’s air-conditioning and heat pump comfort conditioning systems come with a filter-drier, some even come installed. Installing the provided unit only costs a few seconds of braze time and some alloy and gas but will provide the unit with all of the reliability which the system design engineer intended and validated. If the unit did not come with a filter-drier, then installing a properly sized high quality, time proven Catch-All® can ensure contaminants like water, acids, sludges and varnishes are captured before they can react with system materials. These materials may react with compressor windings leading to compressor burnout or cause copper plating which reduces bearing clearances or poor valve seating eventually causing failure. Or they can deposit in the expansion device restricting flow or proper modulation of thermostatic or electric expansion valves. Loss of superheat control can lead to lack of cooling if the evaporator is starved or even worse, flooding of liquid back to the compressor causing bearing washout and eventual compressor failure.
Install a See-All® Liquid and Moisture Indicating Sightglass. This is the only device that can provide a real-time look at the worst system contaminant of them all, water. It also indicates if subcooling is present when it is solidly full of liquid or if it has been lost when vapor bubbles are seen. For negligible cost, it enables the technician to quickly see if the refrigerant has excessive water in it, if the filter-drier needs changing, and a quick check of system charge with just a glance.
Eliminate brazing scale. During brazing, the hot copper can react with oxygen from the air to form copper oxide. This black flakey scale readily detaches from the tubing wall and is pushed around by the refrigerant clogging fine ports and passages in valves, compressors, etc. wreaking havoc on their functionality. Purging the line with nitrogen stops this reaction and should be everyday practice. Alternately, ZoomLock® flame-free refrigerant fittings introduce no heat and will accomplish this goal even easier and faster.
Evacuate the system prior to charging. Pulling a strong vacuum, 500 microns or per manufacturer's instructions, to remove the air has never been easier. Today’s dual stage vacuum pumps are easily capable of achieving this level of vacuum. This eliminates the air that wants to react as well as ensuring full condenser capacity and reduces compressor work. It will also pull water from the tubing surfaces and other components in the system leaving less highly reactive materials in the closed system.
Charge the system properly. A properly charged system will provide the required cooling or heating with the least energy usage and system runtime. Conversely, a low charge will provide less compressor cooling along with poor system capacity/efficiency. Overheating the compressor eventually leads to compressor failure, carbon debris, and sludge-like material formation that will adversely affect the replacement compressor.
Clean-up large systems quickly and completely. Large multiple compressor and multiple evaporator systems are much more difficult to assemble without introducing significant solid debris, moisture, and air. Changing the cores in the liquid line shell and using a secondary filter will capture moisture and solid trash quickly and effectively, even down to very small particles. The clean-up is complete when the See-All indicates the system is dry and the cores/filter-elements have been replaced so they can continue to capture generated debris.
Follow these steps to ensure reliability
Following these simple steps eliminates many of the reliability-robbing contaminants and provides the ability to monitor and remove any contaminants that made it into the system. In addition, the Catch-All will continue to capture solid debris, sludges, moisture, and acids protecting the TEV and compressor. However, routine maintenance of systems can significantly improve their reliability and should not be neglected.
For more information on sizing filter-driers and system clean-up procedures please see Parker Sporlan Bulletin 40-10. For various HVAC and Refrigeration product information visit www.Parker.com/Sporlan.
Article contributed by Glen Steinkoenig, product manager, Contaminant Controls, Sporlan Division of Parker Hannifin.
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