R-22 Conversion - What to Avoid

After reading a lot of technical literature, attending several talks and seminars on R-22 conversion I have developed the following cautions on R-22 conversion.

First and foremost – if you convert a system from R-22 to ANY replacement refrigerant, you are conducting a field experiment on the customer’s equipment using their money. Make sure the customer understands that they are paying for an experiment which may or may not end successfully. I think I would get that in writing.

Since all the replacement refrigerants are zeotropes, they should not be used in flooded systems because they will fractionate in the evaporator.

Since all the replacement refrigerants are immiscible with mineral oil, they should not be used in systems with large receivers (without changing the oil to POE) because the mineral oil will separate and float on top of the refrigerant in the receiver.

Some of the replacement refrigerants have trace amounts of hydrocarbons or POE to help prevent oil logging in the coils and lines. This works well in many systems, but it does not help in the receiver where there is not much refrigerant movement.

DuPont says that the churning in accumulators discourages separation in the accumulator. However, they also say that you may need to add 10% POE if you have oil return problems. 

I am nervous about heat pump accumulators – especially in cold weather when a large amount of the charge is just sitting in the accumulator.

You should NOT weigh in the same amount of replacement refrigerant as R-22 because all the replacement refrigerants are less dense than R-22. A general rule is somewhere around 75-80%.

You should NOT just try to match the pressures you are used to seeing with R-22. A better indicator would be to measure the system subcooling and superheat and shoot for “reasonable” numbers.

You should replace all O-rings and Schrader valve cores before putting in the new refrigerant. O-rings can shrink when exposed to the new refrigerant creating a leak where none previously existed.

You should NOT just add the new refrigerant on top of the R-22. If you do that, you are creating your own special blend which is not EPA SNAP approved.

Just because a refrigerant matches the pressures of R-22 does not mean it will match the mass flow rate. If the mass flow rate is too different from R-22 the metering device won’t work correctly.

Make sure any refrigerant you use is EPA SNAP approved for the application. Any reputable refrigerant will have an ASHRAE refrigerant number and safety rating – not just a trade name or number.

One way to be sure what you are using is safe is to only buy refrigerant from recognizable manufacturers at normal supply houses, not online.

Under NO CIRCUMSTANCES should you use any of the “Organic” replacement refrigerants available on the internet. The “organic” components are propane and butane. They don’t have trace amounts of hydrocarbons, they are ALL hydrocarbon. These refrigerants are NOT EPA approved and they are NOT safe to use in a system which was not designed for flammable refrigerant.

If the customer has already purchased some “organic” refrigerant and tried charging their system, I would not work on the system. It is an accident waiting to happen.

MyHVACLab Survey

To all my friends teaching out of my text, Fundamentals of HVACR, I offer my sincere thanks. David and I really do work all the time at improving the text and its accompanying resources. With that in mind, Pearson has asked me to mention that they are now doing a survey for all their MyLab products, including MyHVACLab. They are offering a $25 honorarium for watching a short video and completing a survey. Below is the text of Pearson's invitation.

Pearson Education, the world’s leading education company, is excited to announce Pearson's MyHVACLab available in your course area.

More than 10 million students used Pearson MyLabs in 2012, and integrated use of these programs has been shown to provide measurable gains in student retention, success, work readiness and overall achievement.

I would like to invite you to learn more about the Pearson MyLab for your discipline, and also invite you to share feedback on how you feel this solution might work for you  and your students. This experience should take you 15- 25 minutes, and in exchange for your time and feedback Pearson will provide you a $25 honorarium.

To get started, goto http://www.pearsonhighered.com/mylabquickreview/

1. Select the MyLab that fits your discipline of expertise
2. Watch the brief video (6-10 min)
3. Complete the survey (7-8 questions)
4. Complete and submit the W-9 form
5. Upon receiving the survey and your W-9, Pearson will process your $25 honorarium

All of the details you’ll need are on this site. Thank you in advance for taking the time to learn more about the Pearson MyLab.  Pearson greatly appreciates and values your feedback. 

HVACR Survivor: The Regional Efficiency Standards Reality TV Show

The legal wrangling over the DOE regional efficiency standards has taken on the air of a day time soap opera, or reality TV. We can call our new program "HVACR Survivor." The May implementation of the regional efficiency standards will be delayed while a legal case works its way through the courts. On May 1 2013, furnace efficiencies were scheduled to start following the ruling. Under this scenario, non-weatherized furnaces in the northern region of the country would have to be a minimum of 90% AFUE. However, the American PublicGas Association (APGA) filed suit against the ruling(APGA suit). The DOE and APGA reached an agreement that would vacate the non-weatherized gas furnace and mobile home gas furnace standards and start the process over to develop a new standard (DOE APGA agreement). The rest of the standard would remain in tact. However, the agreement has to be accepted by the court to go into effect. Heating, Air Conditioning, Refrigeration Distributors International (HARDI) filed a motion with the court to not allow the settlement, and instead, allow HARDI to replace APGA in the lawsuit (HARDI motion). HARDI would like the entire process to start over, not just the part with the furnaces. Since there is a real possibility that this will not be resolved prior to May 1, the DOE has sent out letters stating that it does not intend to enforce the rule pending the court ruling(DOE letter). So for the immediate future, you can still buy an 80% AFUE furnace up in Wisconsin if you want. Whether or not that is a wise thing to do is a topic for another debate. For now, we will just have to wait to see who is voted off the island. Below is an overview of the Regional Efficiency Standards in their original form.

Regional Efficiency Standards Overview

The Federal Department of Energy, DOE, issued a direct final ruling on furnace and air conditioner efficiency in October of 2011. The ruling breaks the country into three regions: North, Southeast, and Southwest regions. A map can be seen at http://www.achrnews.com/ext/resources/NEWS/Home/Images/ApplianceStandards-map-BIG.gif

In a nutshell: in the Northern region furnace efficiency will increase while heat pump and air conditioning efficiency will remain the same; in the Southeastern and Southwestern regions furnace efficiency will remain the same while heat pump and air conditioning efficiency will increase.

Table I.1 Amended Energy Conservation Standards for Furnace, Central Air Conditioner, and Heat Pump Energy Efficiency

Residential Furnaces*
Product Class	National Standards		Northern Region** Standards
Non-weatherized gas	AFUE = 80%		AFUE = 90%
Mobile home gas	AFUE = 80%		AFUE = 90%
Non-weatherized oil-fired	AFUE = 83%		AFUE = 83%
Weatherized gas	AFUE = 81%		AFUE = 81%
Mobile home oil-fired‡‡	AFUE = 75%		AFUE = 75%
Weatherized oil-fired‡‡	AFUE = 78%		AFUE = 78%
Electric‡‡	AFUE = 78%		AFUE = 78%
Central Air Conditioners and Heat Pumps†
Product Class	National Standards	Southeastern Region†† Standards		Southwestern Region‡ Standards
Split-system air conditioners	SEER = 13	SEER = 14		SEER = 14 EER = 12.2 (for units with a rated cooling capacity less than 45,000 Btu/h) EER = 11.7 (for units with a rated cooling capacity equal to or greater than 45,000 Btu/h)
Split-system heat pumps	SEER = 14 HSPF = 8.2	SEER = 14 HSPF = 8.2		SEER = 14 HSPF = 8.2
Single-package air conditioners‡‡	SEER = 14	SEER = 14		SEER = 14 EER = 11.0
Single-package heat pumps	SEER = 14 HSPF = 8.0	SEER = 14 HSPF = 8.0		SEER = 14 HSPF = 8.0
Small-duct, high-velocity systems	SEER = 13 HSPF = 7.7	SEER = 13 HSPF = 7.7		SEER = 13 HSPF = 7.7
Space-constrained products – air conditioners‡‡	SEER = 12	SEER = 12		SEER = 12
Space-constrained products – heat pumps‡‡	SEER = 12 HSPF = 7.4	SEER = 12 HSPF = 7.4		SEER = 12 HSPF = 7.4

The increased standards will be phased in over a period of years. Compliance with the standards in the direct final rule will be required on May 1, 2013 for non-weatherized furnaces and on January 1, 2015 for weatherized furnaces, central air conditioners and heat pumps. Industry reaction has been split. AHRI helped to develop the standards and supports them. They want to avoid the confusion and cost that was associated with the 13 SEER efficiency change that gave the industry very little time to prepare. (looks like we already blew that) AHRI also points to the Canadian experience when they mandated 90% . Their sister organization, HRAI, has stated that there were very few problems with Canada’s implementation of 90% standards. ACCA opposes the standards , especially the 90% furnace mandate, concerned that the extra cost will drive customers to illegal contractors, who feel no compulsion to follow the rules and will cheerfully install equipment that legitimate contractors are not allowed to offer. HARDI also opposes the regional standards, citing the difficulty this will make for distributors who service two or more regions. ACCA and HARDI also cite that there is currently no enforcement mechanism – no DOE police. Again, the problem is that contractors who don’t abide by the ruling achieve a competitive advantage over contractors who do. 

Sucking Through a Coffee Stirrer

Have you ever tried using a coffee stirrer as a straw? I have attempted to use a coffee stirrer as a straw when I was really thirsty, needed a straw, and none were available. After all, they do look like a straw: they have a small hole running up the middle. In fact, you can get a little bit through, but the process is slow and frustrating. The restriction created by the small hole in the coffee stirrer just will not allow very much through. When you connect your vacuum pump up through standard 1/4” hoses, leaving the Schrader cores in the Schrader valves, you are essentially forcing your vacuum pump to draw through a coffee stirrer. It’s not impossible, but very slow and frustrating. The restriction imposed by the Schrader valve and small diameter hoses restrict how much gas can come through, slowing the process down. You can dramatically reduce the time it takes them to evacuate a system by removing these restrictions. In fact, removing the restrictions will do far more than getting a bigger vacuum pump. The same pump you already own can probably evacuate systems in half the time you are accustomed to by simply removing the restrictions (assuming you keep the pump clean and change the oil). The biggest restrictions are the Schrader valve cores. You can buy two vacuum rated core removal tools and dramatically reduce your evacuation time, even using the same hoses and gauges  (so long as they don’t leak). The core removal tools allow you to remove the core, evacuate the system, charge the system, and then replace the cores. Next, you might want to use 3/8” or even 1/2” hoses to evacuate rather than 1/4” hoses that came on your charging manifold. That replaces the coffee stirrer with a properly sized straw. Finally, you should consider using a manifold with a larger bore. Any one of these improvements will make a noticeable difference; all together, the effect is close to amazing. Appion sells a Megaflow Speed kit that packages these three components together. Tru-Tech sells a Rapid Evac Kit that contains the hoses, valve core tools, and some Nylog vacuum sealer. They are both a little expensive compared to standard manifolds or 1/4" hoses, but they work much faster. Just ask yourself this – how much would you pay to cut your evacuation time in half.

If you teach air conditioning, you should contact Appion. They are giving away a vacuum pump to schools that purchase one of their Megaflow Speed Kits. While you are at it, ask for one of their recovery machines too. Note: this deal is just for schools – they are not giving away a recovery machine and vacuum pump with every gauge set sold. E-mail sharon@appioninc.com and ask for details on their educational program.

Warning: After you use better equipment you won’t want to return to your old coffee stirrers.

Does Your Vacuum Pump Suck?

For many technicians, the answer is no – which is bad. Vacuum pumps are supposed to suck. If you are using your compound gauge to tell you when you have a vacuum, you really don’t know what your vacuum pump can do because a compound gauge can’t tell you. The difference between a great vacuum and an awful vacuum just can’t be seen on a compound gauge. It is a little like trying to measure the distance of a millimeter using your car’s odometer. You need a micron vacuum gauge to check the vacuum your pump produces. It is not unusual for a vacuum pump to be in such bad shape that a vacuum gauge connected to it won't register anything. That is not because the gauge is broken, but because the pump does not suck. 

The reason many vacuum pumps in the field do not produce anything close to their rated vacuum or capacity is that their oil is not changed often enough. How often should it be changed? Basically, whenever it gets dirty, it should be changed. You might be able to pull a vacuum on several small, clean systems before changing the oil, or you might need to change the oil in the middle of an evacuation on a particularly nasty system. Vacuum pump oil should be clear. If it has become cloudy or discolored, it needs changing. It is never wrong to change the oil. You normally have several hundred dollars in your vacuum pump even if you got it on sale. Leaving dirty oil in it really does not make economic sense because the crud in the oil is eating up your machine.

The oil not only lubricates the mechanical parts, it also provides the vacuum seal. When stuff is dissolved in the oil, the oil produces a vapor pressure from all the stuff in it – water, refrigerant, flush solution. The vacuum pump cannot pull down any lower than the vapor pressure of the oil in it. So if you have 10W30 instead of vacuum pump oil, or your 10W30 is full of water from all the systems you evacuated this past month, your vacuum pump likely does not suck.  If you have a traditional rotary vane vacuum pump with the oil reservoir on the outside and a sight glass in the middle, you can usually remove that oil reservoir and clean it. We actually change our oil a lot at school – a whole lot more than usually happens in the field. But we still get a good layer of scum on the bottom.  We dismantle our pumps at school at least once a year and clean out all the crud that has collected in the bottom of the oil reservoir. Just pouring oil through does not get the job done. So if your vacuum pump does not suck, try cleaning it and changing the oil.