Do Not Put R-22a in Your Air Conditioner

EPA has taken legal action against them

R-22a, also known as 22a Refrigerant and R-290, is propane often mixed with other hydrocarbons and a substance with an odor like pine scent. It is flammable and potentially explosive and is not a replacement for R-22 also known as HCFC-22 Freon refrigerant which is chlorodifluoromethane. The use of R-22 has been phased out and is not used in new air conditioning systems and heat pumps.

R-22 (also known as HCFC-22) had been the refrigerant of choice for residential heat pump and air-conditioning systems for more than four decades. Unfortunately for the environment, releases of R-22, from leaks, contribute to ozone depletion. As the manufacture of R-22 is phased out over the coming years as part of the international agreement to end production of HCFCs, new residential air conditioning systems are now designed to use more ozone-friendly refrigerants.

Existing air conditioning and heat pump units that use R-22 can continue to be serviced with R-22. There is no U.S Environmental Protection Agency, EPA, requirement to change or convert R-22 units for use with a non-ozone-depleting substitute refrigerant. Such changes are allowed, if the equipment has been properly modified and the alternative refrigerant has been approved for that type of use. R-407C is allowed for retrofits but R-410A is not allowed in retrofits due to its higher working pressures. No change to existing equipment is required, you can just continue to use R-22 because the new substitute refrigerants would not work well without making some changes to system components. R-22a which is being sold as a direct substitute without modification has not been approved by the EPA for substitution into older air conditioning equipment.

According to the EPA, the Clean Air Act (CAA) prohibits the introduction into interstate commerce of substitutes that have not been submitted, reviewed and approved by the EPA and R-22a has NOT been approved. It is illegal to sell R-22a for residential home air conditioners. There is no approved product "R-22a” which is a manufacturer brand name for R-290, propane. In a recent news release the EPA states that R-22a is a potential explosive hazard in home air conditioning systems.

Though EPA has approved the use of propane as a substitute refrigerant in industrial process refrigeration systems and stand-alone retail food refrigerators and freezers that are specifically designed to use flammable hydrocarbon refrigerants, EPA has NOT approved any flammable substitute for home and small commercial air conditioning systems designed to use HCFC-22 or R-22. Home air conditioning systems are not designed to handle propane or other similar flammable refrigerants. The use of these substances poses a potential fire or explosion hazard for homeowners and service technicians.

Propane can be a good refrigerant and the EPA has approved its use as R-290 for commercial and industrial refrigerators and freezers that are systems designed to safely use it. Though EPA ignored for a long time the growing illegal use of propane in home air conditioning systems, they are now deciding what actions should be taken to stop this because it is dangerous. If informed, most certified air conditioning system technician will refuse to work on a system that contains either R-22a (propane) or R-22a mixed in with R-22 (chlorodifluoromethane), so if you try to top off your air conditioning system refridgerant charge with R-22a to save money, you are on your own for maintenance and repair.

Theoretically, there should be no oxygen and no source of ignation in air conditioning and condenser lines, but in real life it happens. EPA reports of explosions and injuries that have occurred both overseas and in the U.S. as a result of the use of propane and other unapproved refrigerants in air conditioning systems. They are investigating and say they will take enforcement actions if appropriate. In the meantime, try not to become an unfortunate statistic to save on the cost of HCFC-22 or R-22.

Remember if you have propane in your system and a part has to be replaced or repaired, welding any portion of the system without first removing the propane could result in an explosion. Any leak in the system could result in explosive gas accumulating in an enclosed area. For safety the air conditioning system should be completely emptied prior to any repair, and since there is no normal recovery equipment for propane, that means completely venting to the atmosphere (allowed for pure propane but not for a propane and chlorodifluoromethane mix) and completely recharging the system. There is no established legal route to recover and dispose of a mixture of R-22 (HCFC-22) and R-22a. Mixed gasses of unknown percent of mix cannot be reclaimed, they have to be safely destroyed.

Upgrading My Heat Pump and Ducts

Though I had always assumed that when the time came I would replace my heat pump with a geothermal heat pump, that’s not what happened. I am replacing my air heat pump with another air heat pump, a more efficient one, and re-ducting the attic to create a more efficient and effective system. The cost to reconfigure my finished basement ($5,000-$10,000) and install either a vertical coil or standing column well ($12,000-$18,000) combined with technical difficulties, limited cost savings and the potential I might impact the drinking water aquifer or damage my garden ended my plans to retrofit a geothermal unit into my existing home.

Lots of things have changed since this house was built in 2004 (with builder grade system). First of all an air heat pump is usually a split heat-pump systems consisting of two parts: an indoor (coil) unit and an outdoor (condensing) unit. Both units are designed to work together.  Heat-pump systems manufactured today, by law, must have a seasonal energy efficiency ratio (SEER) of 13 or higher while my heat pump has a SEER of 12 and a HSPF less than 8. Seasonal Energy Efficiency Rating (SEER) or Heating Seasonal Performance Factor (HSPF) for heat pump systems are the efficiency ratings on heat pumps, the higher the SEER/HSPF, the more efficient the equipment. The SEER is measured in average Btu output over the season divided by the watt hours and is the standard measure of energy use efficiency. The Air Conditioning, Heating and Refrigeration Institute (AHRI), defines the method to measure SEER. AHRI was formed in 2008 by a merger of the American Refrigerant Institute and the Gas Appliance Manufacturers Association. Generally, the higher the SEER/HSPF of a unit, the higher the initial cost and lower the operating cost. For these new, high-efficiency systems to work properly, the outdoor unit and indoor unit must be perfectly matched, properly sized and correctly ducted to deliver the right air flow.

New Energy Star certified air heat pumps have minimum requirements of a 14.5 SEER, 8.2 HSPF and 12 EER or higher. Air heat pumps are available with Up to 20.5 SEER; and Up to 13 HSPF. Two-stage or variable cooling makes this possible.  The heat pump has a compressor with two or more levels of operation: high for hot summer days and low for milder days. Since the low settings are adequate to meet household-cooling demands on all but the hottest days, a multi-stage unit runs for longer periods and produces more even temperatures. Longer cooling run cycles allows a two-stage or multi stage heat pump to remove more moisture from the air and allows you to size the unit for the hottest day capacity without reducing efficiency. The indoor air handler (the fan) provides the energy to move air through the ductwork to the rooms of your house. The high efficiency units also have a variable speed motor that automatically changes speed based on air flow requirements to maintain temperature settings to eliminate the on/off cycling of the blower.

To properly size a system for a home there is Manual J from the Air Conditioning Contractors of America, ACCA. In truth what there really is are several computer models and an iPhone app available that does the calculations for you. The only problems is the input factors that impact the calculation include the climate; the size, shape and orientation of the house; the home's air leakage rate; the amount of insulation installed; the window areas, window orientations, and glazing specifications; the type of lighting and major home appliances; and the number of the occupants. Slight variations in the input assumptions get different results. In the model I played with, baseline inputs were available based on square footage, orientation, age of home and zip code and then adjustments could be made. The results were no better than my back of the envelope calculation, but I know my house, the square footage, orientation, the additional insulation and window films I installed and I figure that the heat pumps should be around 3.675 ton.  My existing heat pump turns out to be 3.5 ton.  Once the temperature reached 90 degrees in Virginia the heat pump ran continuously and could not keep the master bedroom or the bonus room cool and is probably one of the reasons why I am replacing an 8 year old system. The high efficiency two-stage or multiple stage heat pump allows me to oversize the unit slightly so that it can handle the hottest days without sacrificing optimal performance on more temperate days so the old rule that if a system is over sized, the system will cycle on and off too frequently, greatly reducing its ability to control humidity and its efficiency is no longer strictly true. If you are going with a multiple stage system round up.

An essential element to the efficient and effective heating and cooling of your home is the duct system, and there is the Manual D by ACCA intended to ensure a good design.  Many homes built after 2000 have flexible ducting and this could be a problem in the performance of your system. ASHRAE, founded in 1894, is the leader in research focused on building systems, energy efficiency, indoor air quality and sustainability.  ASHRAE sponsors research a various universities to advance the sciences of heating, ventilating, air conditioning and sponsored a series of studies between 2002 and 2006 that found that the airflow loss in flexible ducting in real world installations was 9-10 times the loss anticipated in the 1999 design standard used in Manual D in most homes built during the last building boom. In addition, the experimental results they also found that with compression ratios exceeding 4% (the minimum compression found in the real world), the duct performance varies considerably with slight variations in the installation. A low skilled, inexperienced or sloppy worker does a poor job that will impact the performance of your system.  

The ducts in my well insulated attic

An examination of my ducts in the attic found a poorly executed installation. I should not be surprised since several of the ducts were not properly attached to the distribution boxes when we first bought the home from the lender. I had the ducts sealed when I added additional insulation to the home. The flexible ducts in my attic are R-6 with a black vapor barrier. The flexible ducts consist of three layers an inner core of a metal helix encased in a plastic or foil film, and insulation layer and the outer vapor barrier jacket. While fully extended properly installed flexible duct can be as good at maintaining air pressure as a galvanized steel duct, performance deteriorates as the ducts sag. In all the real world tests there was some degree of compression or sag (more than anticipated) even in good installations. In poor installations there were sharp bends, excess lengths and significant restrictions due to squishing the duct into tight spaces. When the flexible ducts are compressed (or sagging) the inner layer crumples (it is a soft spring) and the helix pops out. Instead of smooth circular tube the flexible duct turns into a bumpy pathway for the air that causes turbulent flow and very significant pressure drop from the beginning to the end of the duct. In my case, almost no air flow in the bonus room.  The scientists at Berkeley Livermore Laboratory and Texas A & M found this effect to be orders of magnitude above the range provided in the ASHRAE design standards. The reason the drop was so great is that the ducts operate at very low pressure and small resistance due to fitting or duct friction can have a very big impact on flow. The scientists calculated pressure drop correction equations so that systems designer could correct for this effect.  

I did not even bother to look for a Manual D computer program. The solution to improving my duct air flow was simply to install galvanized steel trunk lines and distribution boxes, properly sealed with UL 181 foil-backed butyl tape and with R-8 (or higher) reflective insulation. The trunk lines will have straight runs and gentle curves to the distribution boxes, but I am going to use flexible R-8 to tie into the last foot of the vent sleeves (to avoid replacing all the boots) keeping the transition as smooth as possible. I am going to use reflective insulation at a minimum of R-8 to take advantage of what little boost I can get from the decreasing the emittance of the ducts. Radiant barriers on your ducts work in your attic to prevent some of the heat from the roof from being transferred into the ducts. The idea is to have the radiant barrier or coating reflect some of the heat of the attic space away from the ducts. Oak Ridge National Laboratory, ORNL, found in field experiments that radiant barriers installed in the attic could reduce air conditioning bills in the hottest parts of the country, so hopefully I will get some small boost from it. In addition, I will install a temperature controlled attic fan to reduce peak temperatures in the attic, but allow the attic to benefit from southern exposure heat gain in the winter. The new insulated and sealed galvanized ducts and new properly installed reflective flexible duct supply lines to existing registers will add several thousand dollars to the cost, but should significantly improve performance of the system and the galvanized steel portion of the ducts will last for decades. Total cost $16,400. After the work is done I will have to blow more cellulose into the attic to correct what has settled or was disturbed in the installation.