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

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.

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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.

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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.

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