HCFC 22 Rising Faster Than Gold

You may wonder why HCFC 22 has suddenly spiked in price? Although we have all been expecting it to rise because of the phase-out, the rise in the beginning of this year has been dramatic. The phase-out is not all that is behind the latest price increases. Under the phase-out rules, producers and importers must have allocations from the EPA telling them how much product they are allowed to manufacture or import. The EPA has not published the allocation for 2012, so all production stopped on January 1. Nothing drives up price more than not making any more. On January 4, 2012 the EPA published a proposed rule-making that would significantly decrease the amount of HCFC-22 produced or imported compared to 2011. On January 20, the EPA sent a letter to producers and importers promising to not fine them for making HCFC 22 so long as they produced no more than 45% of the allocation set in 2011. So for the month of January, very little if any R-22 was produced or imported. Manufactures and importers can now produce R-22 in limited quantities due to the EPA letter of “No Action Assurance.” The rule may not be finalized until just before this summer. In short, the temporary halt of production and the uncertainty created by the lack of a final allocation and ruling are driving up the price. I would not recomend hoarding R-22 as a replacement for your gold investment  - prices and the market are just too unstable for anyone to predict. Once the final allocation is announced and the panic buying stops - the price may actually come down a little. For more information check out these articles
HARDI
ACHR News

Now might be a good time to look into purchasing reclaimed refrigerant.

Kelvin Melton Sr.

One of the great pleasures of teaching is meeting so many really good people. I enjoy getting to know more about my students than just what their test scores tell me. With so many students starting a second career, we always have a variety of very talented people from all walks of life. One student used to work making custom $5,000 guitars by hand. Others worked as technicians in the telecom industry, and still others in fields such as computer networking. Among this collection of very interesting people, some individuals really stand out for their attitude and leadership. Kelvin Melton always has a smile, an insatiable thirst for knowledge, and a great overall attitude. He is a leader – taking time to help other students. But most of all, he is a consummate professional who truly loves the field of HVACR. Kelvin served his country well – doing two tours as an Army Ranger in Afghanistan. Nobody can outwork Kelvin. He comes to school in the morning after working all night and still is charged up about his studies and sits right up front in the class room. Although I am sure he has had his share of hardships, he never complains, but works diligently towards accomplishing his dream. It has truly been a pleasure to work with him these last two semesters. His enthusiasm inspires other students to up their game. Kelvin died unexpectedly at home two days ago at the age of 26, cutting his promising HVACR career short. I must admit that I am still trying to make sense of it myself. One thing I can truly say is that Kelvin was not waiting for someone else to fulfill his dreams – he was actively pursuing them with every fiber of his being. If you have something that you want to accomplish or a dream to work towards, don’t wait – start working today towards the fulfillment of your goals and dreams. When you get there you can thank Kelvin for showing you how its done.      

Heat Pump Temperature Rise

One of the best ways to check the refrigerant charge of a heat pump during the heating season is to measure the temperature rise across the indoor coil and compare it to data published for that unit. The two main issues with this charging method are getting the required data and measuring the system airflow. Not all manufacturers publish the temperature rise for their equipment. Another potential problem is system airflow. The amount of temperature rise achieved is directly related to the amount of air moving across the coil. If the ACTUAL airflow is different from the manufacturer's stated conditions, the temperature rise will also vary. Increased airflow will reduce the temperature rise and decreased airflow will increase the temperature rise. For the temperature rise method to work, the system must be operating with the correct airflow.

Heat pumps are rated by AHRI for heat output at two outdoor temperatures, 47°F and 17°F. The indoor return air temperature rating point is 70°F. Most heat pumps produce a heat output of close to their "tonnage rating" at the 47°F AHRI rating point and approximately half of their "tonnage rating" at 17°F. Most units operate correctly with an airflow somewhere in the range of 400 CFM per ton of capacity. Of course these are generalizations.

However, a general idea of temperature rise parameters can prove useful. Using these generalized assumptions, let's develop some generalized temperature rise performance parameters. The basic formula to use is BTU = 1.08 x CFM x TEMP RISE. This can be rewritten as TEMP RISE = BTU / (1.08 x CFM). At 47°F the capacity per ton will be 12,000 BTU. Plugging this into the formula we get TEMP RISE = 12,000 / (1.08 x 400). This yields a projected temperature rise of 28°F at a 47°F ambient. On the other end of things, the assumed capacity per ton at 17°F ambient temperature is 6000 BTU. Plugging this in we get TEMP RISE = 6000 / (1.08 x 400). This yields a projected temperature rise of 14°F. You can readily see that the result of a 50% reduction in capacity yields a 50% reduction in temperature rise. Now let's test our mathematical extrapolations against some REAL data taken from a manufacturer’s performance specifications.

Model	ΔT  @ 47°F	ΔT  @ 17°F	BTUh  @ 47°F	BTUh  @ 17°F	CFM
ERHQ18	26°F	13°F	18,500	11,000	700
ERHQ24	25°F	12°F	24,400	12,500	800
ERHQ30	27°F	16°F	32,200	18,800	1055
ERHQ36	26°F	13°F	36,000	19,500	1310

The manufacturer states that a properly operating unit should be + or – 3°F of these typical values. You will note that our extrapolated values are all within the 3°F margin of error.

But what if the temperature is neither 47°F nor 17°F, what temperature rise do you look for then? Another assumption is in order here; we will assume that the capacity reduction due to ambient temperature drop is even. Since the temperature rise changed from 28°F to 14°F over a 30°F ambient change, this would represent approximately a 1°F change in temperature rise for every 2°F change in ambient temperature. In the above table, we see a temperature rise change of 13°F in 3 out of the 4 units listed. This gives similar results. In our assumed system, 28°F rise at 47°F ambient and a 14°F rise at 17°F ambient, a temperature rise of 23°F would be expected at 37°F ambient based on the relationship of 1°F rise per 2°F ambient temperature. Clearly, manufacturer's data for a specific unit is more accurate than extrapolated benchmarks; however, extrapolated temperature rise calculations are considerably more accurate than blocking the outdoor coil and pretending it's summer. Remember: the best method for charging any unit is the method recommended by the people who made it!

What is an LMS?

A Learning Management System, or LMS, is a software approach to organizing and administering a course. Typically, learning management systems are used for online classes. An LMS is basically a web site construction kit that is targeted to education. The LMS allows teachers to manage rosters, design the flow of the course, deliver online content, administer assessments, and calculate grades. For most of us, trying to do just one of these on our own without would be a daunting task. The learning management system makes it possible for teachers to design and administer structured and effective online courses that would probably not be possible without the tools provided by a good learning LMS. Of course web content and technology can be used in traditional classrooms as well as online. The learning management system just makes this far easier. This is not to suggest that today you acquire LMS software and next week you are launching your own Cyber University. There is still quite a learning curve. Because these systems typically can do a lot of things, there is a lot to learn. Although there are many similarities in the different systems, each really has it’s own unique interface and set of tools that you must learn. Compared to the work in a traditional lecture course, I would say there is more work on the front end and less on the back end. This is especially true the first time you offer a course using an LMS. However, the beauty of technology is that once you have that course built, saving, maintaining, and reusing it is relatively easy.

There are many choices for LMS software includng the Open Source program Moodle, commercially hosted systems such as BlackBoard, or systems managed by publishers such as MyHVACLab. Moodle is free, but like all open source freeware, there is a cost, it is just not money. There is good documentation on how things work, but you pretty much have to figure it out for yourself because there is no paid support. There is an active community where you can often get questions answered, but there is no “tech support.” If you are a Linux fan and use Open Office for your general day to day office software, you would probably be very comfortable using Moodle.

BlackBoard is probably the largest and most well known commercially hosted LMS. Many publishers provide Blackboard course “cartridges” to accompany their texts. A cartridge is a collection of resource files, such as pictures, presentations, or test banks that can be loaded into Blackboard to make developing a course easier. Typically a school or school system pays Blackboard to host their courses, allowing teachers to develop courses using their system. Blackboard takes care of the hosting and provides technical support. A downside to this type of hosting is that you can lose all your courses if you decide to go with another system. Our Technical College System switched from Blackboard to Angel a few years back, and the change was abrupt and traumatic. 

A third option is an LMS hosted by a publisher such as Pearson. Pearson has been offering online courseware for many years. One of the most well-known is MyMathLab which is used by thousands of schools all over the country. Publisher managed learning management systems are usually designed to support a particular text, so integration with the text is very easy. A big advantage of the publisher systems is that they deliver a finished product, ready to use. Moodle and Blackboard deliver a platform on which to build, but you still need to build the courses. MyHVACLab accompanies Fundamentals of HVACR. It is a complete course including e-book, interactive activities, and assessments all organized around the structure of the book. You can still make the course your own by editing, rearranging, adding, or deleting; but you start out with a complete course right out of the box. Also, you don't have to worry about your school system's contract expiring and losing all your classes. MyHVACLab does not cost the school anything to use. Instead, students pay a modest access fee. When bundled with the book, the cost is usually only $!5 - $20 more than the cost of a book by itself. 

This post is a little long, but we have just scratched the surface. There is no question that using an LMS requires a good deal of effort, but I believe if you make the effort you will find it very rewarding.

Exploding Refrigeration Containers

Prices for HCFC 22 are finally rising to the levels that were expected this past summer. With the rise in refrigerant price will come increased interest in replacement refrigerants. For your safety as well as your customers safety, make sure you know where your refrigerant comes from. Avoid bargains from people you don’t know. This is not just about obeying the law, it is also about safety. Several container refrigeration systems have exploded after being charged with counterfeit R-134A. Container refrigeration is more difficult to patrol because the containers travel all over the world. Three articles discussing the accidents involving the mystery replacement refrigerant can found World Cargo News, ACHR News, Huffington Post.

Although flammable refrigerant s can be used safely, systems using flammable refrigerant use components designed for that use. Systems designed for flammable refrigerant also have limits on the amount of charge in the system and carry warnings regarding the flammability of their refrigerant. To stay safe, only use SNAP approved replacement refrigerants and only purchase refrigerant through the normal supply chain.

AHR Expo 2012

The AHR 2012 Expo is happening this week at the McCormick Place in Chicago. It runs Monday January 23 – Wednesday January 25. The AHR Expo is the granddaddy of all air conditioning industry shows. It is co-sponsored by two of the HAVC/R industry heavy hitters: ASHRAE and AHRI. This is truly a world class show with people and companies from all over the globe. My experience has been that it is really impossible to look at all the exhibits in a day because there is so much to see. If you are located anywhere close to Chicago and can find a day to visit the expo, it is well worth your time. Instructors and students can get so much free literature that it will take you hours just to read it all. There are many free seminars every day for discussion of new technologies and products. The AHR Expo is usually where HVAC/R companies roll out their latest and greatest, so it is a perfect place to see where the industry is heading. Perhaps most useful to instructors are the contacts you can make with OEM suppliers, manufacturers, wholesalers, and industry technical gurus of all stripes. You may not be able to swing by this year, but you can still see who is there and even take a look at some of their info via a virtual show feature on the AHR Epo web site. On the main page of their site are photos and tweets. At the top of the main page is an Exhibitors menu. One selection in the middle of the list is AHR Expo TV. Videos of different vendors booths are available to see the the booth without traveling to Chicago. Also, check out the exhibitors list. There are so many, that it is organized as a search. When you get to a specific vendor, their contact information is listed. This is a great tool for searching who's who in the HVACR field. So if you can't swing by the Windy City, take a virtual tour.  

Transcritical Refrigeration

There has been a lot of work in the last decade on using carbon dioxide as a refrigerant. It is inexpensive, non-flammable, non-toxic, compatible with most materials, relatively friendly to the environment compared to fluorinated refrigerants, and has the potential to be quite efficient. There is one large obstacle to using CO² as a refrigerant: its critical point. The critical point is the highest pressure and temperature where the refrigerant can still condense. At and above the critical point there is no distinction between gas and liquid, so no condensation or evaporation can take place. The very top of the hump in a refrigerant enthalpy diagram is the critical point. A normal refrigeration system is a subcritical system because all the system components operate at pressures and temperatures below the critical point. (See Unit 18 in Fundamentals ofHVACR for more details on refrigeration enthalpy diagrams.) The problem is that critical temperature for CO² is 88°F. The condenser saturation temperature for most refrigeration systems is above 88°F, especially for air cooled systems that must use hot outdoor air for cooling the condenser. This prevents the use of CO²  in a “normal” refrigeration system which uses an evaporator to absorb heat and a condenser to reject heat.

One application of CO²  refrigerant is called a transcritical system because part of the system operates above the critical point and part of the system operates below the critical point. Subcritical, supercritical, and transcritical all describe a refrigeration system’s operating pressures and temperatures relative to the critical point of the refrigerant in the system. A typical “normal” refrigeration system is a subcritical system because everything happens below the critical point. In a supercritical system, all the components operate at pressures and temperatures above the critical point. A supercritical system operates on gas compression and expansion with no change of state. All heat transfer occurs by the gas changing temperature. A transcritical system operates both above and below the critical point. Heat is absorbed in an evaporator where liquid evaporates to a gas, but heat rejection takes place above the critical point, so there is no condensation in what normally would be considered the condenser. The refrigerant does not condense back to a liquid until after the pressure is reduced. For more details on transcritical refrigeration systems, see Unit 85 Commercial Refrigeration Systems in Fundamentals of HVACR, 2nd edition.