Saturday, August 16, 2014

Caught One!

The lead story of the August 11, 2014 Air conditioning Heating and Refrigeration NEWS is “Man Gets Prison Time for Venting R-22.” In this particular case he was stealing copper – he just did not bother to recover the refrigerant first. The police literally caught him in the act, and knowing what he did was a Federal violation, reported him to the EPA. Now he is serving 31 months in prison. Truthfully, most people who steal copper or vent refrigerant are not caught. However, this case proves that you CAN be caught, and there is a substantial penalty.  Some people do the right thing because that is the way they conduct their lives. Others need some external reinforcement to avoid doing what they know they are not supposed to do.  Without penalties for breaking the rules, these folks will ignore the them. Hopefully this incident will be widely publicized so that other potential thieves in need of external reinforcement will consider another line of work. Or at the very least, steal something that does not involve venting refrigerant.

Here is a link to the story Prison Time for Venting Refrigerant

Sunday, August 10, 2014

Oxy-Acetylene Torch Safety

One of my e-buddies, Dave Christensen, suggested that I write about oxy-acetylene torches. He recently bought a new torch and confessed that he read the instructions before using it. In the instructions, he noticed that the regulator settings were different from the ones he had used for years. When we teach students to use torches in school, we typically teach them the regulator settings that work for the equipment we have. I am afraid we may not always make sure students understand that torch settings are not universal. The correct regulator setting depends upon the torch manufacturer, the tip size, and the application. Torch manufacturers typically provide these settings in the instructions.

There are a few guideposts that stay the same. For example, you NEVER, NEVER, NEVER set acetylene above 15 psi. In fact, I get nervous above 10. The reason is that acetylene is unstable at pressures above 15 psi and can explode. So how does it not explode in the acetylene cylinder at 250 psig? It is dissolved in acetone liquid which is stabilized in a porous core. That is why you should never transport or use acetylene cylinders on their side – it lets the liquid run out of the cylinder into the valve area. Also, you really don’t need the oxygen above 20 psig. Many tip charts have it about half that for most applications. However, the exact settings you should use are ... in the instructions!

Another common safety issue is leaving your regulators set and just opening and closing the tank valves when you want to use the torch. This is convenient and saves time, but it is dangerous. Regulators can fail because of the sudden bump in pressure. This can cause parts to fly and high pressure gas to stream down the hoses. The last thing you should do when shutting off your torch is to adjust the regulator T handles out counterclockwise until all the spring pressure is released. When the cylinder valves are opened they should be in this position. AFTER opening the cylinder valves you can adjust the regulators to he correct pressures.

When lighting the torch, you should light the acetylene first by itself and then bring in the oxygen. Opening both the acetylene and oxygen simultaneously can cause oxygen to flow into the acetylene hose and regulator if the oxygen pressure is higher than the acetylene pressure. This can create a very dangerous situation – a mixture of fuel and oxygen under pressure in the hose and regulator. The only place we want this type of combustible mixture is in the tip.  When shutting down, reverse the process. Close the oxygen first and then the acetylene.

Torch manufacturers have some very good training material available for free. Here are some links to some good training resources.

http://training.victortechnologies.com/

http://www.harrisproductsgroup.com/en/Products/Equipment.aspx

http://uniweld.com/en/uniweld-videos

Saturday, August 2, 2014

Stubby Gauges

Anyone who has ever disconnected a hose from a Schrader valve knows about the spray you get as a result. If you are taking a hose loose from the liquid line there can be quite a lot of very cold refrigerant spraying out. Many people don’t realize that the spray is usually NOT coming from the Schrader valve, but from the hose! The spray is from refrigerant that is trapped in the hose coming back out when you loosen the hose. By my calculations a standard 5 foot 1/4” hose holds about 3.5 ounces of R22 liquid. Releasing it is bad for the atmosphere, bad for the system, and bad for you if it gets on your skin. If the system was perfectly charged before you connected your gauges, it is no longer after you take them off.  If you were to connect a 5 foot hose to the liquid line of a dorm refrigerator and fill up the hose, you would essentially suck most of the charge out into your hose and gauges. Of course you would first have to install a piercing valve or two – creating potential leaks to boot.

My point is that you don’t always need to connect your gauges to every system you see – especially small critically charged systems. Even on larger systems, if you are connecting gauges just to check the system operation, consider getting a couple of “short gauges.” These are essentially a gauge mounted on just enough tube to connect it to the system. They hold a minimal amount of refrigerant, so the amount released is much less. This saves the atmosphere, is better for the system, and is way better for your fingers. Here is a link to a picture of a set of stubby gauges used in an article on ice machine service found in Contracting Business Magazine.



Sunday, July 27, 2014

EPA Proposes Ban on R-404A and Other Refrigerants

You may have heard that the EPA is proposing to ban the use of some common refrigerants  I would like to give a brief overview of things you should know about this proposed ruling. First – at this stage it is still a proposal – not a ruling. Typically the way this works they publish a proposed ruling, allow us to comment on it, revise the ruling based on the comments (if they choose to), and publish the final ruling.  Since this is still a proposed ruling, you have a little time before it will take effect. Second, not all industries are affected by this ruling. Air conditioning caught a break – air conditioning systems are not covered . However, motor vehicle air conditioning IS covered. For motor vehicle air conditioning the big news is that 134a will no longer be acceptable in NEW VEHICLES beginning January 2016. A large number of zeotropes are also banned from use in new vehicles, but most of those are mainly used today as an R12 substitute. That should not have a great effect because they are only banned in NEW vehicles.

Retail refrigeration appliances and vending machines are also covered. The big news here is that R507 and R404A will be considered unacceptable for both new AND retrofit applications in retail refrigeration beginning January 2016. Retail refrigeration would include things such as display cases in grocery stores.

Four areas that are NOT covered by this proposed rule (yet) include cold storage warehouses, ice machines, refrigerated transport, and industrial process  refrigeration. However, the EPA is specifically asking for comments about the possibility of using low GWP refrigerants in these areas as well.
 “EPA requests comment on the use and viability of both low-GWP refrigerants (e.g., R-744, R-717, and HCs) and other HFC-blends (e.g., R-407A and R-407F) and the possibility of listing R-404A, R-507A, and other high-GWP blends unacceptable in any or all of these four end-uses.” I encourage you to do some of your own research into this. Here is a link to the proposed RULING. Here is a link to a FACT SHEET about the ruling. Here is a table summarizing the proposed changes to the auto air conditioning and retail refrigeration refrigerants.


Refrigerant Uses Deemed Unacceptable as of January 1, 2016
End-use
Substitute
Further Information
Retail food refrigeration (new and retrofit)
R-404A
R-404A is a blend, by weight, of 44% HFC-125, 4% HFC-134a, and 52% HFC-143a. It has a high GWP of approximately 3,920. Other substitutes are available for this endues with lower overall risk to human health and the environment.
Retail food refrigeration (new and retrofit)
R-507A
R-507A is a blend, by weight, of 50% HFC-125 and 50% HFC-143a. It has a high GWP of approximately 3,990. Other substitutes are available for this end-use with lower overall risk to human health and the environment.
Retail food refrigeration (condensing units and supermarket systems) (new)
HFC-227ea, R-407B, R-421B, R-422A, R-422C, R-422D, R-428A, R-434A
These refrigerants have GWPs ranging from 2,729 to 3,607. Other substitutes are available for this end use with lower overall risk to human health and the environment.
Retail food refrigeration (condensing units and supermarket systems) (retrofit)
R-407B, R-421B, R-422A, R-422C, R-422D, R-428A, R-434A
These refrigerants have GWPs ranging from 2,729 to 3,607. Other substitutes are available for this end use with lower overall risk to human health and the environment.
Retail food refrigeration (stand alone units only) (new only)
HFC-134a
HFC-134a has a Chemical Abstracts Service Registry Number (CAS Reg. No.) of 811-97-2 and it is also known by the name 1,1,1,2-tetrafluoropropane. HFC-134a has a relatively high GWP of 1,430. Other substitutes are available for this end use with lower overall risk to human health and the environment
Retail food refrigeration (stand alone units only) (new only)
FOR12A, FOR12B, HFC-227ea, IKON B, KDD6, R- 125/290/134a/600a (55.0/1.0/42.5/1.5), R-407A, R-407B, R-407C, R-407F, R-410A, R-410B, R-417A, R-421A, R-421B, R-422A, R-422B, R-422C, R-422D, R-424A, R-426A, R-428A, R-434A, R-437A, R-438A, RS-24 (2002 formulation), RS-44 (2003 formulation), SP34E, THR-03.
These refrigerants have GWPs ranging from approximately 550 to 3,607. Other substitutes are available for this end-use with lower overall risk to human health and the environment.
Vending machines (new and retrofit)
R-404A
R-404A is a blend, by weight, of 44% HFC-125, 4% HFC-134a, and 52% HFC-143a. It has a high GWP of approximately 3,920. Other substitutes are available for this endues with lower overall risk to human health and the environment.
Vending machines (new and retrofit)
R-507A
R-507A is a blend, by weight, of 50% HFC-125 and 50% HFC-143a. It has a high GWP of approximately 3,990. Other substitutes are available for this end-use with lower overall risk to human health and the environment.
Vending machines (new only)
HFC-134a
HFC-134a has a Chemical Abstracts Service Registry Number (CAS Reg. No.) of 811-97-2 and it is also known by the name 1,1,1,2-tetrafluoropropane. HFC-134a has a relatively high GWP of 1,430. Other substitutes are available for this end use with lower overall risk to human health and the environment
Vending machines (new only)
FOR12A, FOR12B, IKON B, KDD6, R- 125/290/134a/600a (55.0/1.0/42.5/1.5), R-407C, R-410A, R-410B, R-417A, R-421A, R-422B, R-422C, R-422D, R-426A, R-437A, R-438A, RS-24 (2002 formulation), SP34E.
These refrigerants have GWPs ranging from approximately 550 to 3,085. Other substitutes are available for this end-use with lower overall risk to human health and the environment.

Saturday, July 19, 2014

Dryer Sheets In The Coil

Recently, two different techs have told me stories about finding dryer sheets used creatively in customers air conditioning systems.  When they asked their customer why there were bunches of dryer sheets stuck to the air filter, the customer said they liked the “clean, fresh scent.” Another story involved customers removing supply registers and stuffing  dryer sheets across the outlet of the register to “filter and freshen” the air. Naturally, some of these found their way to the coil where they clogged the coil and caused enough air flow restriction to freeze the system up. In all cases, dryer sheets stuffed into clever places only serve to restrict the airflow. Even if they did not, all you are accomplishing is introducing whatever chemical is on them into your system. They don’t remove odors – they just add more. Honeywell used to sell a system to do that called the “Scentrol.” Scentrols used little gel cans that looked like sterno. They system controlled how much air circulated over the can to regulate the scent. It even had a wall control. My father sold one to a customer who also bought an electronic air cleaner with an activated charcoal filter to remove smells. The customer insisted on having the Scentrol installed, even after dad explained that they were buying one machine to put smells in the air and another to take them out. Here is a link to an online forum that has a picture http://www.hvacproforums.com/threads/honeywell-scentrol.1148/

So what do you suggest to customers who want the air conditioner to improve their home’s odor? I don’t think you can buy a Scentrol anymore. First, try to find out if there are specific odors they are trying to get rid of. Finding and eliminating the source is really the best option. My brother once discovered that the kitchen sink drain leaving the disposal had never been connected on a new house in which the customers were complaining about dirty sock syndrome. If the odors are system related, look at the condition of the indoor coil and make sure there are not problems such as a leaky return in a crawl space. If they just like the idea of having a “fresh scent” system there are a number of filters that use activated charcoal to absorb odor. Just check that the pressure drop across the filter is not too high. Like the famous 1” pleated filters, some of the charcoal filters can add enough restriction to cause an airflow problem even when they are clean. Another option would be an air cleaner that uses titanium dioxide and UV light to eat up compounds that cause odors. Both Field Controls and Lennox make air cleaners that use this technology.  Now you are on the high end of the cost spectrum, but you are dealing with solid, reputable companies who sell things that work.

Sunday, July 13, 2014

Check System External Static BEFORE Sealing Ducts

I recently read a thought provoking article by David Richardson in the July 7 Air Conditioning Heating and Refrigeration News. In it he argues that sealing an undersized duct system can cause problems. The system cooled BEFORE you sealed the ducts, and now that you have worked on it, the system cannot move enough air to stay operating. I know I have seen many systems with marginal ductwork that still managed to operate, even if inefficiently. The duct leaks could be allowing just enough extra air flow to keep the system operating. The combination of leaks on both the return and supply sides of the system serve to reduce the static pressure difference against which the fan must move the air. If the static pressure difference between the return and supply is already at or past the limit the manufacturer publishes for their system, sealing the ducts will increase the already high static pressure difference and push the system over the edge. This is why Mr. Richardson advises taking a reading of the total external static pressure difference BEFORE sealing the duct to avoid this trap. If it is too high, the duct system will need more attention than just sealing – it will need some duct modifications as well. Better to know before you do the job. What is too high? I don’t like to see anything higher than 0.8” wc – that is usually the top end on most residential systems. Most residential systems will operate comfortably around 0.5” wc. Some will go all the way to 1” wc, but at a cost. With ECM fan motors you are burning electricity to shove air through restrictive ductwork. With PSC blowers you lose airflow at high external static pressures. This costs electricity in another way. The suction pressure drops, the compression ratio increases, and system capacity decreases – causing extended run times and inefficient operation.

Thursday, June 26, 2014

Blast from the Past

I ran into a Carrier unit yesterday that had the old compression type access valve on the suction line. I realized that there are probably many techs working today that may have never seen one of these. They were common in the late 1970’s. Most units came that way, with compression fittings for the refrigerant lines. Every manufacturer had their own type of compression nuts and ferrules. Sometimes the ferrules were shipped with a plastic plug in them and the nut hand tightened. More than once I had a unit where the nut was a little too tight and the ferrule was compressed around the plastic plug, making it useless. I don’t expect we will see those return, but I wanted to point out that what was once commonplace is no longer even recognized by most people in the field. I am sure there is technology that is common today that will seem equally strange in another 30 years. Knowing the mechanical fine points of today’s equipment is valuable for working efficiently, but that information will be next to useless in ten years. Understanding how and why systems operate and why things are done the way they are is more lasting. The physics behind the basic refrigeration cycle has not changed in 30 years and is not likely to change in another 30 years because it is based on laws of physical science. What types of connectors the refrigerant lines have, what the metering device looks like, what wires are used for control, what type of motors a unit has, or even what type of compressor it has can all change drastically in 30 years. What won’t change are the concepts of saturation, pressure temperature relationship, superheat, and subcooling. Learn all you can about why systems work because that knowledge will be the foundation you will use for understanding tomorrow’s systems. Knowing which heat pumps available today energize the reversing vale on orange and which energize on blue probably won’t be a lot more useful than being able to differentiate a Carrier ferrule from a York ferrule is today. By the way, here is what the Carrier compression access valve looks like.