Archive for the ‘Richard Travers’ Category

How Often Do My Evaporator Fans Need to Run?

Thursday, March 12th, 2015

Walk-in cooler owners have often asked if it is really a good idea to switch off the evaporator fans inside their coolers.  Sometimes, this is after a refrigeration serviceperson has flatly declared that the evaporators should never be turned off. Understandably, people are concerned with two key issues. First, they want to make sure the system works and keeps the cooler and its valuable contents properly cold. Second, they do not want to risk damaging their system.  As I’ll discuss below, intelligently shutting down your evaporators does not compromise the system’s ability to keep the cooler at the desired temperature, nor does it create potential to damage the compressor system.

First, to get some context, let’s look at how things currently work. Since the earliest commercial mechanical refrigeration systems were installed, evaporator fans have been kept running constantly, 24/7/365.  The main reason for this is simple: evaporator coils can become clogged with ice.  An iced or frosted evaporator does not have sufficient airflow through it, so it does not cool properly and creates the risk that a cooler will get too warm.  It is essential to completely defrost the evaporator coils periodically to provide effective and efficient refrigeration. A traditional system relies on an oversized compressor and a time clock to ensure that the compressor stays off long and often enough when the compressor is not running to melt all the ice. In the old days, before the advent of computer controls, it was safer and easier to simply keep the evaporator fans running than to risk not having them on when needed.  Determining when they can safely and efficiently be switched off is too much for old-fashioned mechanical controls.

A modern computerized control like the Freeaire® Cooler Controller can handle that job. When it determines that it is time for a defrost cycle, it will shut down the compressor so that no refrigerant is coming into the evaporator and will run the evaporator fans to warm evaporator coils until they reach a target temperature that indicates that there is no ice remaining. In other words, the Controller will run the fans only long enough to completely defrost the system, but no longer.

Some suggest that it is necessary to constantly run the evaporator fans during the compressor’s off cycle to provide adequate circulation to prevent temperature stratification or temperature variations within the cooler. That job can be easily done with much less energy by installing a low wattage, but high airflow, circulating fan that operates whenever the evaporator fans are off or by switching on the evaporator fans for a few seconds every few minutes.

The second issue that people bring up is whether turning the evaporator fans on and off is somehow dangerous for the system. An “old school” refrigeration guy that brings this up is probably concerned with “slugging” the compressor. In English this means that refrigerant would be sent back from the evaporator to the compressor as a liquid rather than as a gas. This could happen if the compressor is on, sending refrigerant to the evaporator, but the evaporator fans are not running. Our Cooler Controller is designed so that whenever the compressor is running, so are the evaporator fans. This helps to ensure that the refrigerant evaporates and returns to the compressor as a gas.

To prevent slugging of the compressor, however, it is even more essential that two common compressor safeguards be used, especially in winter in a cold climate. The first is a pumpdown solenoid that causes almost all the refrigerant to be pumped out of the evaporator and the return pipe and to be safely stored on the output side of the compressor before it is switched off. The second safeguard is a crankcase heater that makes sure that any refrigerant that does remain behind stays as a gas that cannot harm the compressor when it resumes operation. These two measures are particularly important with a Freeaire system using outside air, since there could be many hours, weeks, or even months between when a compressor shuts off and when it finally switches on again. All Freeaire systems should have these safety features installed if they aren’t already.

Another concern comes from some people’s perception that repeatedly switching the evaporator fan motors and relays will harm the motors. In fact, it is better to have them off than on. Like most mechanical devices, an electrical motor, including a modern ECM evaporator fan motor, is subjected to less wear and tear when at rest than when running constantly. Solid-state relays can switch evaporator fans off and on many times a day for decades without failing.

A Freeaire® system saves energy by not running the evaporator fans unnecessarily. However, this in no way compromises proper refrigeration or does harm to any part of the system.

It’s (NACS) Showtime!

Wednesday, September 21st, 2011


Freeaire systems have been used successfully in a wide variety of environments — breweries, food processors, server rooms, etc. — almost any situation where a product needs to be kept in a cooler with a size of 1000 cubic feet or greater.  It’s a very flexible, reliable system with many possible applications.

That being said, Freeaire systems have always found particularly wide acceptance in convenience stores, going all the way back to when founder Richard Travers had his “eureka!” moment on a cold Vermont winter night and started tinkering with the refrigeration system at the Warren Store.

Since that moment more than 20 years ago, Freeaire systems have been installed in hundreds of separate retail locations throughout the United States and Canada.

energy consumption in convenience stores

Refrigeration can be the largest single source of energy consumption in a convenience store

The reason that Freeaire systems are popular in convenience stores is simple: Refrigeration makes up a large percentage of the overall energy consumption in this environment.

The Freeaire system dramatically reduces energy consumption over conventional refrigeration systems and produces significant energy savings.

The president of Champlain Farms, a 38 store chain in Vermont and New Hampshire, said installing Freeaire systems in all of his stores was “one of the best business decisions he ever made” (read the complete case study here).

With this track record in mind, we’re excited to be participating in the NACS (National Association of Convenience Stores) annual trade show, October 1 – 4, in Chicago.  Going to an event of this magnitude is a big effort for us but we know that we have a story to tell.  We are looking forward to meeting with prospective customers in a face-to-face environment.   Our next-booth-neighbors will be Tim Hortons so come by and smell the doughnuts!

Planning on being in Chicago for the show?  Please come by booth 2950 and say “Hi” — we’d be thrilled to meet you!

What is the Opposite of Solar Energy? Part Two

Tuesday, July 12th, 2011

By Richard Travers

The answer to this question is revealed in the ancient Chinese view of the universe in which opposite and equal qualities form a dynamic whole. “Yang” literally means “sunny place”, while “yin” means “shady place”.  We’re talking about the sun and the lack of sun. Using this line of thought, the opposite of the heat of a bright summer day is the cold of a dark winter’s night. The tropical and sunbaked regions near the equator are the opposite of the frigid poles. What form of energy is more plentiful in the shade, at night, in the winter, and at the poles? Give up?

Polar Energy, that’s what.  Polar energy is yin to solar energy’s yang. It is the polar opposite of solar energy.

The sun is the source of energy, light and heat that living things need to survive. Polar energy can be thought of as the absence of solar energy. When we have less sun it gives us shade, night, and winter, essential factors in the life cycles of living things. With too much solar energy we would all die from the heat.  With too little we would die from the cold. Just the right balance between these two extremes makes the earth hospitable to life in all its forms. Ours is the Goldilocks planet. Not too hot, not too cold, but just right.

We use solar energy to grow our crops, heat our homes and even to generate electricity. Polar energy is harnessed by humans and our technology in fewer obvious ways.

Low-tech tools such as opening windows can cool our houses at night.

Higher-tech tools include air conditioning systems that often use “economizers” to bring cool outside air into a building at times to save energy by running their compressors less.

My company Freeaire Refrigeration of Waitsfield, Vermont, manufactures energy-efficient commercial refrigeration systems for walk-in coolers, freezers and cold storage warehouses. A Freeaire® refrigeration system harnesses what we like to call Polar Powertm in a surprisingly direct and effective way: it brings winter air inside. A conventional commercial refrigeration system uses lots of expensive electricity to make cold air with a compressor, even in the winter. A Freeaire® system uses much less energy to run fans to move naturally cold outside air into the refrigerated space whenever the weather is cold enough. No matter how the electricity is generated we use Polar Powertm and other efficiency measures to conserve energy, generating “negawatts” that cancel out the megawatts. The return on investment for Freeaire® systems is usually much faster than for photovoltaic solar systems.

Our state is full of examples of how we Vermonters take advantage of one of polar energy’s most visible and versatile manifestations: snow. Snow sports abound here. When the natural variety is not adequate, ski areas can actively make snow to cover their slopes. Outdoor skating rinks often make their ice with an even simpler technology than passive solar that you might call “passive polar”. Just flood the rink and let the winter sky do its thing.

With the 45th parallel, halfway from the equator to the North Pole, passing through our state, Vermont lies in the temperate overlap of the solar south and the polar north.  Even one of our favorite agricultural products, maple syrup, is best made when the days are warm but the nights are cold.

It is time to recognize that polar energy has been and should continue to be an important part of our state’s energy mix. It’s time to officially give polar energy the recognition as a legitimate form of renewable energy. Polar Powertm to the People!

Freeaire’s experience at ASHRAE in Montreal

Friday, July 8th, 2011

By Richard Travers

A couple weekends ago I was pleased to attend the ASHRAE 2011 Annual Conference in Montreal. The ASHRAE, otherwise known as the American Society of Heating, Refrigeration, and Air Conditioning Engineers, is a well-known conference where experts in the field meet, learn, and educate others with technical lectures. The conference allows time for committees to decide on the details of the various standards that the ASHRAE develops that are widely accepted by building code organizations throughout the world. It also provides the attendee with a glimpse of trends in the industry that will be apparent within the near future.

Although, I have not received a degree in engineering, like many of the attendees, I am a self-trained engineer and have been working in the field almost my entire adult life. I joined the organization in February and have attended many of the trade shows throughout the past year, but this was my first Annual Conference. I went in with a clear mind provoked to learn new things regarding the industry that Freeaire is part of, can relate to and gain advice from. As expected, it was a weekend that had my brain working overtime!

The day before the formal conference began, I got a head start and attended a daylong educational course on data center energy efficiency. The next day I attended about a dozen hour-long technical sessions with topics including:

  • Fan selection criteria
  • Ice arena HVAC & R
  • Measuring and modeling walk-in cooler performance
  • Efficiency in refrigerated warehouses
  • And; more on data center cooling

These sessions were very educational and many of the topics fit hand-in-hand with Freeaire’s mission- saving more energy. A huge buzz-word throughout the conference was, “net-zero”, a concept of a building generating as much energy as it uses. Terms such as, “energy efficiency”, and, “carbon reduction” were also mentioned as goals in almost every session that I attended!

Surprisingly, I learned that by 2020 data centers might possibly be using more energy then the commercial airline industry! I learned that these data centers do not necessarily need to be air conditioned to 68 degrees, as many are, but can operate the computer systems fine at 75 degrees, which saves more energy in the process…and in the long run.  I also became aware that the demand of the cooling process is rising because of the increased heat. Data centers need to take this into account because there needs to be a plan to increase the capacity of the cooling system, to protect the components, over time- as the Earth’s heat rises.

I was gratified to learn that an airside economizer with the ability to control humidity, a product that is similar to Freeaire technology, is a very promising approach to data center cooling.

During the efficiency in refrigerated warehouses session, I learned that one speaker from California was unaware of economizers being used for cooling. After his lecture, I was able to share with him the Freeaire technology, and point him to our website. This was exciting because it proved that education can be a two-way street!

I also learned many acronyms that I had never heard before, to share a few;

As a whole, the conference was very educational and informative. It was nice to learn new trends and discuss technological ideas with other folk in the industry rather then attending an event where products and technology are being pushed. (It is forbidden by the organization to share any names of any commercial product by an attendee or a speaker to prevent the opportunity for sales or disparage of potential competitors.) I was thrilled to learn that so many others within the industry have the same goal as Freeaire- to be efficient while saving energy – therefore reducing their carbon footprint.

Next year the ASHRAE Annual Conference will be held in San Antonio, TX. Despite the location not being as convenient as the trip to Montreal, I am excited to attend and learn more at ASHRAE 2012!