HVACR Tech Tip: Protect Your System During Maintenance With These Steps

Simple maintenance steps for system reliability

There are simple steps that an HVACR technician can take during their routine spring and fall inspections or at any time when onsite to enhance reliability. The good news is that most of the items listed below are commonly followed for system efficiency and capacity maintenance but also positively affect system reliability. Performing these simple steps greatly enhances the probability that a system will last its full design life.

1. Maintain coil cleanliness. Dirty coils lead to reduced airflow, cooling capacity, efficiency, and increased compressor operating temperatures. One compressor manufacturer told me that overheating compressors is the number 1 cause of compressor failure. Coil cleaning saves on operating costs while enhancing system reliability and avoids unnecessary system downtime and repair costs.
2. Maintain proper charge quantity. Undercharged systems cause the compressor and all system components to work unnecessarily. Low charge also causes higher compressor operating temperatures which lead to failure over time. Properly charged systems run efficiently and cool keeping compressor temperatures low.
3. Fix leaks. Leaks lead to low charge and all the problems discussed in the prior blog Protect Your System During Install With These Steps. In addition, as refrigerant leaks out, moisture and air will enter the system albeit in small quantities. The Catch-All® will protect the system by capturing the moisture, at least until its capacity is fully used. After this, even small intrusions over time leads to oil or refrigerant degradation, corrosion, and other equally bad results.
4. Change the Catch-All filter-drier. During normal operation the Catch-All filter-drier is capturing any water molecules that are in the system components, capturing the wear particles from compressor operation and other particles flushed from components or tubing. In essence, it is similar to the oil filter on your car or truck engine and needs to be replaced on the AC system you are working on. Below are the guidelines for when to replace the Catch-All filter-drier:
   1. Anytime the system is opened. It is not possible to know how much capacity of the Catch-All has been used nor how much contaminants will be added to the system during the repair. Replacing the Catch-All ensures it has sufficient capacity to capture the introduced water and debris and capture the materials normally expected to be generated over time.
   2. Anytime the See-All moisture indicator shows water is present. Water will react and that reaction is always detrimental. The Catch-All capacity has been exceeded and needs replacing.
   3. Anytime the Catch-All pressure drop causes loss of subcooling or 5 psi pressure drop. The Catch-All has captured enough solid debris to cause excessive pressure drop. If the filter-drier is cooler than the inlet side tubing, then subcooling has been lost and the Catch-All needs replacing. The Catch-All, like air filters, need replacing when it has done its job.
   4. Anytime an acid check of the oil shows high acid level. When the TA-1 acid test kit shows high acid, it has surpassed the capability of the Catch-All. It is imperative to replace the Catch-All and remove the acid as quickly as possible before it harms system components. In addition, review the compressor operation to ensure it is not experiencing a slow burnout (internal electrical short) that is turning refrigerant and lubricant into acids, sludge, and solid debris. If a compressor burnout has occurred, follow the clean-up procedure in Parker Sporlan Bulletin 40-10. Below are some of the key steps in this process:
      • Install an oversized liquid line Catch-All to dry the system, capture acid, and solid debris. This protects the TEV from plugging.
      • Install a properly sized suction line Catch-All to rapidly capture acid and solid debris to protect the compressor.
      • Replace the two Catch-Alls until pressure drop of both stops increasing and acid level is satisfactory when checked with the TA-1 acid test kit.
5. After clean-up operation is completed. Once any clean-up is done, replace the liquid line Catch-All with a standard size and remove the suction line unit or replace it. This renews the protection the Catch-All and provides for continued contaminant control. This step is often overlooked.

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.

 

 

 

 

Additional resources for you:

HVACR Tech Tip: How to Apply Filter-Driers on Heat Pumps for System Protection

HVACR Tech Tip: Protect your System During Install With These Steps

HVACR Tech Tip: When Should a Catch-All Filter-Drier be Changed?

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

1. 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.

2. 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.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

 

 

 

 

Additional resources for you:

HVACR Tech Tip: How to Apply Filter-Driers on Heat Pumps for System Protection

Use of Suction Line Filter-Driers for HVAC Clean-up After Burnout

HVACR Tech Tip: When Should a Catch-All Filter-Drier be Changed?

Not everyone is familiar with all the intricacies of HVACR as we are at Parker Sporlan and that’s okay. Whenever you have questions, you can always contact our world class Technical Support team or check Parker.com/Sporlan for in-depth information and guidance. Our Climate Control Blog has many of the answers you need for questions on most topics, so dig in. Below, we’ve answered some of the most frequently asked Thermostatic Expansion Valve (TEV) questions – you’ll find easy answers to your need-to-know questions.

  Where should the TEV external equalizer be installed?

The purpose of the external equalizer is to sense the pressure in the suction line AT THE BULB LOCATION and transmit it to the TEV diaphragm. This usually means installing the external equalizer immediately down stream from the bulb. This ensures the correct pressure is signaled to the TEV. In some situations, this “ideal” location may not be possible. In these cases, an alternate location could be used. However, the pressure at these locations must be nearly identical to the pressure in the line where the bulb is located. In other words, alternative locations are acceptable as long as these pressures are essentially the same as when the system is operating at full load. In the past there has been concern about installing the external equalizer “up-stream” from the bulb. This was due to the possibility of refrigerant leaking past the TEV push rods, passing through the equalizer line and into the suction line, thus falsely influencing the TEV bulb temperature. Today, with Parker Sporlan’s TEV design, this possibility is virtually eliminated.

  Where should the TEV’s bulb be located?

In general, the TEV bulb should be installed on a straight section of horizontal suction line. When the compressor is above the evaporator – Locate the bulb on a straight, horizontal line, pitched slightly down, immediately after it leaves the evaporator. A short trap should follow before the vertical line rises to be connected to the compressor suction. With the line pitched down, any liquid refrigerant and/or oil will pass into the trap, away from the bulb. As the trap fills with oil, the velocity of the refrigerant will carry the trapped oil into the vertical section and be returned to the compressor. When the compressor is below the evaporator – No trap is required after the bulb location, but the line should be pitched slightly down to prevent any liquid refrigerant or oil from being trapped at the bulb location. When several evaporators are installed both below and above the common suction line – Observing the same principles outlined above, the piping should be arranged to prevent the accumulation of oil and/or refrigerant at the bulb location. Also, traps installed in the suction lines of evaporators prevent the refrigerant from one evaporator from entering the suction line of another evaporator.

  Should a Parker Sporlan Thermostatic Expansion Valve (TEV) be adjusted after installation?

Before leaving the factory, a specific superheat setting is made on each and every Parker Sporlan TEV. A standard superheat setting has been established for every size and every thermostatic charge. This standard-setting provides the proper superheat on the average system to which the particular TEV size and charge is likely to be applied. Therefore, in most cases, a superheat adjustment on the job will not be necessary. Parker Sporlan recommends a change in the superheat adjustment only after it has been determined that it is required. Careful measurement of the operating superheat, using the recommended procedure, will establish if a change would be beneficial. To reduce the superheat, turn the adjusting stem COUNTERCLOCKWISE. To increase the superheat, turn the adjusting stem CLOCKWISE. When adjusting the valve, make no more than one turn of the stem at a time and observe the change in superheat closely to prevent over-shooting the desired setting. On adjustable TEVs, Parker Sporlan attempts to position the adjusting stem at the half-way point when it is at the standard-setting. This allows maximum adjustment in both directions. Parker Sporlan supplies a number of OEMs with non-adjustable TEVs. The OEM determines the superheat setting through laboratory testing of the unit. Some of these valves can be converted in the field to adjustable models.

  How can I tell if my TEV is adjustable?

Most of the TEVs listed in Parker Sporlan Catalog 201 or Bulletin 10-10 will be adjustable unless there is an “N” stamped in the valve body as part of the nomenclature (i.e. NSVE-5). Many of the valves made specifically for OEM customers are non-adjustable. One way to tell if a valve is adjustable or non-adjustable is to look at the bottom cap. Adjustable expansion valves will have a threaded joint between the valve body and bottom cap as well as a threaded joint between the bottom cap and a hex seal cap that is removable to expose the adjusting stem. Non-adjustable valves, on the other hand, will generally have only one threaded joint between the valve body and bottom cap. An exception to this rule is a factory adjustable valve with two threaded joints and a smooth, round non-removable seal cap. Many non-adjustable valves can be converted to adjustable by changing the bottom cap assembly. Contact Parker Sporlan’s Technical Support department for more information. They will need all the information you can get from the valve’s markings to assist you. CAUTION: Never attempt to determine if a valve is adjustable by removing the bottom cap assembly unless the system has been pumped down, it could result in serious injury.

  Can I replace the powerhead on my Parker Sporlan TEV and how do I know what to get?

With a few exceptions, most Parker Sporlan thermostatic expansion valves manufactured after 1993 have replaceable thermostatic elements. The exceptions are valves with an “H” before the valve nomenclature (i.e. HSVE-10), the now obsolete Platform valves, and the relatively new HX valve. The Platform and HX valves can be identified by a stainless steel element. The valves with the “H” in the nomenclature have had the elements soldered to the valve body at the customer’s request. Parker Sporlan makes replacement element kits that are available through Authorized Sporlan Wholesalers. The thermostatic elements on Parker Sporlan expansion valves are identified by a series of numbers and letters. The number (i.e. 33, 43, 83, etc.) identifies the element size, while the letters (i.e. VGA, RC, JCP, etc.) identify the refrigerant and thermostatic charge. A replacement element kit can be obtained based on that information. For example, a valve with markings on the element of 83 and VCP100 will require a KT-83-VCP100 element kit. (For more information on element identification, consult Bulletin 210-60.) If markings on the element are no longer legible, contact Parker Sporlan’s Technical Support team for help in selecting a replacement element. They will need all the information available from the valve body, and a description of the application. To completely identify a Parker Sporlan thermostatic element the following information is required:

• Element size number

• Refrigerant Thermostatic charge

• MOP (Maximum Operating Pressure) if other than standard E

• Capillary tubing length

• Bulb size if other than standard

For more information on Thermostatic Expansion Valves (TEVs) download a copy of Bulletin 10-10. For more troubleshooting information download a copy of 12 Solutions for Fixing Common TEV Problems - Form 10-143.

 

HVACR Tech Tip Article contributed by Jason Forshee, application engineer,  Sporlan Division of Parker Hannifin

 

 

 

 

 

Additional HVACR Tech Tips helpful for you: 

HVACR Tech Tip: Basic Troubleshooting Given Three Measurements

HVACR Tech Tip: Principles of Thermostatic Expansion Valves

HVACR Tech Tip: Where Should the TEV External Equalizer Be Installed?