Monday, March 11, 2013

Converting Away From R-22

Editor’s Note: The following article was prepared by ICOR International and references some technologies and products specific to the company.

With the impending phaseout of R-22 looming, the price and availability of the product will soon make it impractical to use.

With virtually tens of millions of R-22-designed a/c systems in operation, refrigerant users and equipment owners will need to employ a number of alternative options to satisfy their cooling needs. Due to the special application designs and cooling requirements found in multifamily structures, there are a unique set of challenges in maintaining cooling equipment and fewer practical options.

It is illegal to purposely vent any refrigerant. All refrigerant users must possess an EPA 608 certification (required by law under The Clean Air Act) to recover all refrigerants. Recovered refrigerants are to be recycled or returned to an EPA-registered reclaim service provider (one example of which is Refri-Claim []).

The law does allow equipment owners to recycle and reuse refrigerants in their own equipment without processing it through a reclaim company. However, this practice adds additional costs in the form of equipment, labor, and energy, and, if done improperly, can create additional service problems and even equipment failures.

Equipment Replacement

HFC-410A is the non-ozone depleting replacement of choice by new equipment manufactures. Since R-410A operational pressures are much higher than that of R-22, R-410A-designed systems incorporate unique materials and components. For this reason users cannot use R-22 in an R-410A-designed system, or use R-410A in an R-22-designed system. The refrigerants must be segregated and used only in systems designed for their unique characteristics.

Even though R-410A is a highly efficient refrigerant and the equipment’s physical footprint does not pose any new challenges, the cost of replacing an existing R-22 designed system with an R-410A system may be impractical. With most multifamily systems, the evaporator (indoor unit) has a much longer lifespan than does the condenser (outdoor unit). However, R-410A pressures require the replacement of the outdoor unit as well as the indoor unit. And since R-410A systems require the use of a product specific lubricant — POE oil — the system piping (line sets) must be flushed with a special solvent to remove any build up along the piping walls.

Refrigerant Conversion

For equipment owners with a restrictive budget, full equipment replacement to R-410A may be impractical.

The simplest and least costly option to maintaining an existing piece of R-22 equipment is to convert the system to a direct replacement refrigerant. For example, HFC-422B (marketed by ICOR International as NU-22B) is a non-ozone depleting, nontoxic, and nonflammable direct replacement that nearly duplicates the operating characteristics of R-22. System conversions to R-422B do not require the use of any product-specific materials or components. Therefore decision-makers can extend the lifespan of both the indoor and outdoor units and avoid any costs associated with flushing or replacing system piping.

The Conversion Process

Here is the conversion process using R-422B as an example:

1. Recover all of the R-22 from the system following EPA regulations.

2. Complete all necessary system services and repairs.

3. Pressurize system and performance leak check.

4. Pull system into a vacuum.

5. With the system off, initially charge R-422B in the system to 80 percent of the original R-22 charge as a liquid. Note: Charging a system with R-422B as a vapor will reduce system performance.

6. Start system and allow pressure to stabilize.

7. To maximize system performance on a fixed orifice system, check compressor superheat; on expansion valve units check system subcooling. Adjust charge as necessary. Note: Refer to the original equipment manufacturer’s superheat and subcooling specifications.

8. Leak check the system and establish preventive maintenance schedule.

A special note: For large-tonnage equipment or unique systems, and or applications, contact ICOR’s Tech-2-Tech department for conversion assistance. Do not use R-422B or any other 400 Series refrigerant in a flooded evaporator application.

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