Climate Control

As we introduced our Parker Sporlan webinar series we realized that we couldn't possibly answer all the questions in that short amount of time. We decided to create Climate Control blogs to answer some of the more pressing questions. This is the first of three blogs answering questions from our Supermarket Seminar Series: Metering Devices, TEVs.

Q: What if you can only mount the sensing bulb on a vertical suction line?

A: There are times when no other option is available. When one of those times happens, go ahead and install the bulb on the vertical suction line; however, this is a compromise. But how about installing an appropriate length of horizontal tubing at the evaporator outlet and before entering the trap for the riser? Now there is adequate room on a free-draining, horizontal length of tubing to install the bulb.

Q: If you must place the bulb on a vertical line. Does it matter how it is oriented, tail up or tail down?

A: Keep in mind, the vertical line is not the preferred location; however, there are times when no other option is available. If the thermostatic charge is a liquid type, the position of the capillary tube makes little to no difference concerning the bulb. If it is the MOP style charge, it might make a difference. If that is the case, it would be best to install the bulb with the capillary tube pointing toward the sky or "tail up" as you have suggested. Then, route the capillary tube so that it is physically above the bulb location and even insulate it as a final precaution.

Q: Should the sensing bulbs or the thermistors, in the case of electrically actuated-electronically controlled expansion valves (EEVs), be insulated on the pipe?

A: Yes, insulating the bulb or thermistor is good practice. This helps reduce external influences on the bulb or thermistor. It also helps to manage condensation.

Q: Do we need to apply thermal mastic between the sensing bulb and the pipe?

A: If you follow Sporlan's recommended installation practices, thermal mastic should not be required.

Q: What is the max evaporator pressure drop before you need an external equalizer?

A: The pressure drop is rather small, in the range of 1 to 3 psid depending upon the refrigerant. Keep in mind, an externally equalized valve is necessary any time a refrigerant distributor is present in the system. One could substitute an externally equalized valve as a replacement for an internally equalized valve in just about any application. You simply need to install the equalizer line appropriately. The reciprocal is not true. If an externally equalized valve is required, an internally equalized version of the valve will not suffice.

Q: Why is the equalizing line connected downstream of the sensing bulb?

A: However unlikely, it is possible for an internal leak to develop in some thermostatic expansion valves (TEVs). In the event of a pushrod seal leak, refrigerant could be introduced into the low side of the system by way of the external equalizer line. This possible leak could influence the operation of the TEV by inadvertently cooling the sensing bulb and thus telling the valve to modulate to a more closed position. Positioning this connection downstream of the sensing bulb minimizes any interaction with the sensing bulb in the event an internal leak does occur in the TEV.

Q: Is the pressure tube typically connected after the distributor and before the coil?

A: If by "pressure tube," you mean the equalizer line, no, it must be installed and connected downstream of the evaporator. And better yet, it should be connected to the suction line downstream of the TEV sensing bulb. The distributor is on the inlet side of the evaporator between the TEV and the evaporator

Q: I've never seen an externally equalized valve with the second tube leaving the TEV. Are they uncommon?

A: No, externally equalized valves are not uncommon at all. In fact, most of the valves that Sporlan manufactures are externally equalized.

Q: Typically, I use an externally equalized valve for 4,000 BTU and up. Is that a correct approach?

A: It is a safe bet to utilize the externally equalized valve for almost any application. If the pressure drop across the evaporator coil is greater than 1 to 3 psid depending upon the system refrigerant, an externally equalized TEV is required. If there is a distributor in the system, an externally equalized valve is required.

For more information on TEVs see Parker Sporlan Bulletin 10-10-8, Bulletin 10-9, Bulletin 10-10.

For more information on Parker Sporlan products please visit our website.

Article contributed by Jim Jansen, senior application engineer, Sporlan Division of Parker Hannifin

Additional resources on HVACR Tech Tips:

HVACR Tech Tip: Understanding and Preventing Superheat Hunting in TEVs

HVACR Tech Tip: Everything You Want to Know About Superheat

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

In a basic vapor-compression refrigeration cycle there are 4 primary components that we need to consider. 

1. Compressor: Compresses low pressure temperature vapor to a high pressure temperature vapor.
2. Condenser: Vapor rejects heat to ambient (air, water, etc.). Vapor condenses to liquid. Pressure constant if no glide.
3. Metering Device: Device has a small orifice, high pressure drop. Liquid changes from 100% liquid to saturated liquid vapor mix with an associated drop in pressure at relatively constant enthalpy.
4. Evaporator: Refrigerant absorbs heat from the refrigerated space. Refrigerant boils/changes phase. This should be 100% vapor at the evaporator outlet.

The modern refrigeration system is advanced and can seem complicated and each one is different. Some installations have multiple/distributed racks throughout the store. Other designs include one or more compressor racks in a mechanical room with split suctions intended to satisfy both low and medium temp refrigerated cases. These systems may include different refrigerants, condenser types, unloading, sub-coolers, heat reclaim and head pressure control.

The condenser is located on the high side of the system and is connected to the discharge line. Installed near the condenser may be heat reclaim and split condenser valves along with head pressure controls. The heat reclaim and split condenser valves are part of a complete head pressure control package.

During the refrigeration process, heat is transferred from a place where it is objectionable (like the place you are trying to cool or freeze) to a place where it can be rejected, like the great outdoors. The transferred heat to the ambient can be used for another purpose instead of rejecting it. By utilizing the 3-way heat reclaim valve, the otherwise discarded energy can be redirected to provide supplemental store heat or to preheat water.

When the valve is de-energized, it’s flow exits through the valve to the normal condenser. Note: refrigerant should be bled from the reclaim coil (or the condenser coil in some instances) to the suction side of the system when not in use. 3-Way valves (ex. S12D13B) with internal bleeds can bleed refrigerant from the idle condenser or use an auxiliary solenoid valve, restrictor and check valve as an optional method.

The 3-Way solenoid valve is energized when reclaimed heat is required. This sends refrigerant through the reclamation heat exchanger (the water heater in this case) and then on to the normal condenser. In the series arrangement, the water heater de-superheats the refrigerant and the condensing process occurs in the normal condenser. Refrigerant should not condense in the water heater. In the series arrangement refrigerant always flows through the normal condenser. When the reclaim coil is idle, trapped refrigerant should be bled to the suction to be utilized in the remaining parts of the system. The check valve should be used in the reclaim “pump out” or bleed line whenever the reclaim heat exchanger is exposed to temperatures lower than the saturated suction temperature of the system. This will prevent refrigerant migration to the coldest location in the system which could be the coil.

When piped in parallel, the heat reclaim coil must be large enough to fully condense the refrigerant on the high side. Because the heat reclaim valve is a solenoid style product, it shifts as opposed to modulates, and 100% of the system refrigerant flow will go to one coil or the other. Remember, the idle coil should be drained of refrigerant either by using an auxiliary solenoid valve or the optional internal bleed feature of the B-version 3-way heat reclaim valve. The B-version is only capable of bleeding one condenser coil back to the suction side. The remaining condenser will need an auxiliary solenoid to bleed refrigerant when that coil is idle.

1. Coil burnout.
2. Failure to shift to reclaim mode.
3. Failure to shift to normal mode.

1. Improper electrical characteristics.
2. Continuous over-voltage, more than 10%.
3. Under-voltage of more than 15%. This applies only if the operating conditions are such that the reduced MOPD causes stalling of the plunger, which results in excessive current draw.
4. Incomplete magnetic circuit due to the omission of the plunger assembly during reassembly.
5. Mechanical interference with movement of plunger which may be caused by a deformed enclosing tube.
6. Coil energized while not installed on a valve.

1. Coil burnout.
2. MOPD greater than specifications.
3. Restricted high pressure pilot connection. Pilot connection requires a 50 psi differential (discharge to suction).
4. May not have allowed sufficient time to pump out the reclaim coil while in the normal mode.

1. Stray voltage holding plunger up.

2. Restricted, closed service valve, or capped suction connection on pilot.

In addition to these failure modes, dirt or contamination is ultimately one of the biggest system problems that can occur. There may be a possible refrigerant leak causing low receiver level if flash gas is present at the expansion valve outlet. As a temporary fix, you can deactivate the reclaim. If the heat reclaim output is too low, there is likely a head pressure control issue.

For additional information on 3-Way Heat Reclaim Valves, download Parker Sporlan Bulletin 30-20 or visit the product page here. For more information on HVACR products and literature visit Parker.com/Sporlan.

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?

What’s changing in HVAC? It might be simpler to ask what isn’t changing.
According to Steve Yurek, the president and CEO of the Air-Conditioning, Heating, and Refrigeration Institute (AHRI), the industry is facing change on all fronts.

1. There’s trade uncertainty due to the imposition of tariffs.
2. A federal government that is unwilling to deal with environmental and energy issues.
3. And rapidly rising temperatures tied to increasing greenhouse gas emissions affecting urban building codes.

And that’s just for starters.

Now add in the level of change contractors and distributors are facing on the job - with new refrigerants, growing automation, complex sensing and monitoring technologies, the advent of smart controls, predictive residential diagnostics, the ongoing push for green buildings, even how contractors are communicating with customers - and perhaps it’s understandable why HVAC professionals seem to be a vanishing breed. In fact, the Bureau of Labor Statistics (BLS) estimates the current HVAC technician shortage at 70,000, with an additional 115,000 new HVAC/R professionals are needed to meet the demand within the next four years.

Download the related white paper, How to Capitalize on HVAC/R Trends to Drive Business Growth and learn what actions contractors and distributors must take now, to capitalize on environmental responsibility trends.

Read more about this topic:

How Greener Materials and Technologies Are Impacting the HVACR Industry

HVACR Trends in Green Building with GreenStar and LEED

The IoT is Transforming the HVACR Industry--Are Stakeholders Ready?

How to Use Virtual Engineer for HVACR Product Selection

To obtain reliable performance with solenoid valves on refrigeration or air conditioning systems, it demands careful consideration of application requirements during the selection process. Parker Sporlan offers a wide variety of solenoid valve sizes and styles which may be employed in refrigeration and air conditioning systems to electrically control refrigerant flow. Solenoid valves are electrically operated ‘stop-valves’. These are either fully open or fully closed. Remember these do not modulate flow.

Solenoid valves are typically classified according to the stem and plunger action.

1. Direct acting – Energizing the coil directly opens the main port of the valve allowing full flow. A direct acting valve pulls the plunger against inlet pressure and is typically limited to small applications or where there is a low-pressure differential across the valve.
2. Pilot operated – Energizing the coil opens a pilot port which releases pressure above the main disc/piston/diaphragm allowing it to move to an open position for full flow.

A pilot operated valve makes use of pressure differential across the valve to allow for higher flow capacities without the need of a large solenoid coil. A minimum of 1 psi pressure differential is required to allow the disc/piston/diaphragm to return to its normal position. This is THE key statement, without a minimum pressure drop across the valve, once in operation the main port will not return to normal.

There has always been a tendency in the industry to select solenoid valves based on line size. However, due to the pressure drop required for proper operation, this policy is risky and not recommended.

In other words, if a liquid line solenoid valve is being selected for a system having 5/8-inch OD liquid line, there is a tendency to select any valve having 5/8 ODF connections. For example, we have 4 valve series with 5/8 OD connection sizes ranging from 6.0 tons to 23 tons. If a capacity of 15 tons is required, choosing solely based on line size can lead to detrimental scenarios.

1. Under-sizing and a starved evaporator.
2. Grossly oversized valve which will not have the minimum 1 psi pressure drop and its disc/piston/diaphragm will NOT return to its normal position.

Choose solenoid valve based on system capacity with a minimum of 1 psi pressure drop. Then choose from available connection sizes. If the desired connection sizes are unavailable, bushings and couplings can be used to adapt to the existing line size, which will NOT affect valve performance.

Example: 15 ton, R410A, Liquid Line Solenoid valve with 5/8 OD connections:

Options:

1. E14, a little over 3 psi pressure drop across the valve and has 5/8 OD option
2. E19, a little over 1 psi pressure drop across the valve only 7/8 OD option

In this example, the E14 would be the best option. The reason is the load on the system may drop thus causing a marginally sized valve to be too big.

For more information on solenoid valves please see Parker Sporlan Bulletin 30-10. For various HVAC and Refrigeration product information and solutions visit www.Parker.com/Sporlan.

Article contributed by Henry Papa, sales engineer, Sporlan Division of Parker Hannifin.

Additional resources for you:

HVACR Tech Tip: What You Need to Know About Flooded Head Pressure Control

HVACR Tech Tip: Everything You Want to Know About 3-Way Heat Reclaim Valve Applications

HVACR Tech Tip: What is Important in Refrigerant Distributor Performance?

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.

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.

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?