Month: December 2017


Dehumidification features are common on residential systems ever since the introduction of variable speed blower motors. The system is set up so that the blower can produce less CFM per ton when latent (humidity) load in the space is higher than the setpoint relative humidity. Slowing the blower increases moisture removal by reducing the sensible load on the evaporator coil and therefore dropping the coil temperature and surface dewpoint.

Most variable speed fan coils and furnaces have a terminal designated for Dehumidification and it can be called D, dehum, DH or something else depending on the manufacturer.  In all cases I am aware of, this dehumidification terminal must be energized for the blower to go to full speed and when that terminal is de-energized the blower speed (usually) drops to 80% of full speed.

For years we have seen thermostats with designated dehumidification terminals to match up with the fan coil/furnace terminal, so it was just a matter of disconnecting a jumper from the dehumidification terminal to the R terminal in the unit and connecting a wire from the designated thermostat terminal to that dehumidification terminal in the unit. The diagram below is an example of this on an old Carrier Thermidistat with a variable speed Carrier fan coil.

We now have 24v control smart thermostats like Ecobee, Cor, Nest and Lyric with a lot more flexibility in how they can be set up rather than having a single, designated dehumidification terminal.

I am a big fan of EcoBee for many reasons including their Alexa integration, remote wireless sensors and application flexibility… but you need to be really careful with how you set them up, ESPECIALLY when setting up dehumidification.

The image above is a GIF and should show you the first part of the dehumidification setup. I am setting it up for a single speed compressor heat pump with a variable speed fan coil. EcoBee has contacts labeled acc+ and acc- that can be set up to do a wide variety of functions. For this typical dehumidification function using the system you would select Menu>Installation Settings>Dehumidifer >1 Wire ACC+>Open contact state to activate dehumidifier.

This setup uses 24V power from the R terminal to energize the acc+ terminal and therefore the dehumidification terminal in the fan coil/furnace when there is NO call for dehumidification.

Now for a controversial part. Go to the equipment menu and select Dehumidifier to “dehumidify with fan”= no. We have seen several occasions where the blower continues running with no cooling call if this setting is set to yes when there is a dehumidification demand and no cooling demand.. According to the EcoBee website HERE it appears to say the opposite, but we have confirmed on a few occasions that this occurs and there appears to be no adverse effects from setting it to off becasue the blower is still controlled by the thermostat for cooling operation and dehumidification without cooling is not possible without an external dehumidifier.

In order for the system to over cool below the temperature setpoint to dehumidify you need to go into the thresholds menu and set up AC over cool Max to the maximum temperature below setpoint that would be allowed during dehumidification by the equipment.

— Bryan



All fuel-burning appliances require oxygen to burn and sufficient oxygen to burn clean and safe, without soot and CO (Carbon Monoxide).

I live and work in Florida where most of our fuel-burning appliances are 80% efficient with open combustion that utilizes air and oxygen from the space for combustion.

With these low-efficiency appliances whether the appliance is forced vented or natural draft that combustion air is leaving the space, and exiting the flue.

This causes negative pressure that must be allowed to equalize as well as consumes oxygen from the space. It is because of this that these open combustion appliances must either be in a sufficiently large space or communicate with (be open to) a larger space or outdoors.

When you consider that other gas appliances also need to use oxygen and need to vent to outside you can see that without sufficient communication to outdoors that negative drafts can occur on natural draft appliances like water heaters.

This is why all open combustion appliances that utilize combustion air from inside the space must be in an “unconfined space” or connected to an unconfined space or the outdoors using an approved method.

I see many furnaces jammed into tight closets and mechanical rooms with little thought or planning regarding combustion air.

According to NFPA 31, 54 & 58 an unconfined space is a space that has at least 50 cubic feet of open area for every 1,000 Btu of input. This means that a 100,000 Btu furnace must be in a 5,000 cubic ft space to be considered unconfined.

If the appliance is not unconfined then additional combustion air must be made available to the space with one opening at the ceiling level and one near the floor.

If the air is coming from another unconfined space then the openings should be at least 1 square inch per 1,000 BTU and 1 square inch per 5,000 BTU if it is connected to the outdoors.

While these openings and are needed in many cases to allow for proper combustion and venting it helps illustrate why modern sealed combustion “direct vent” appliances that take all of their combustion air from outdoors make so much sense.

Not only are direct vent appliances more efficient on the fuel utilization side, they also prevent the negative home pressures and/or thermal losses associated with having vents in walls and ceilings.

So either make sure you have an unconfined space, you are bringing air in from an unconfined space or outdoors or you have a direct vented appliance.

— Bryan

Every year…. We watch it EVERY YEAR and it still gets to me again and again. Call me a sucker, but especially living a blue-collar life working in the trades It’s a wonderful life describes the way many of us live, and even more so the way we can start to feel about our lives and our life’s work. Now, if you HAVE NEVER watched “It’s a Wonderful Life” don’t read this until you do… it won’t make sense.

We work day in and day out, for people and with people who don’t always notice what we do or see the value in it (or so we think). The truth is (like the movie reveals) we all matter more than we think. What we do, and to even a greater extent WHO WE ARE has an enormous impact on others and the world around us.

But this story isn’t about you or me, this story is about compression refrigeration and what it did to transform the world

Remember Mr. Potter from the movie? Take a good look at the man above, those fluffy white mutton chops belong to Frederic Tudor, and this grouchy looking man is the “Mr. Potter” of our tale…

but let’s not get ahead of ourselves

The year was 1806 and Frederic Tudor returned from a trip to the Carribean with the idea that exporting ice from the lakes and ponds of Massachuchets would be his path to fortune, and he was right, but not right away.

The Ice failure

Now, Frederic Tudor (from here on referred to as Fred) DID NOT invent the idea of using ice to cool food and drinks… as long as humans have roamed the earth they have been using ice for one thing or another. What Fred did was to create a commercial ice TRADE, and at first, he was REALLY bad at it. Fred’s first few shipments of ice from Massachusetts to the Carribean island of Martinique ended in failure, not only because much of the 80 tons of ice had melted away but also because the locals saw no need for Fred’s frozen water. Most of the ice, like Fred’s dreams of profit, just melted away.

In fact… between the years of 1809 and 1813 Fred racked up some major debts he couldn’t pay, debts that landed him in prison THREE TIMES, this was Massachuchets after all and they didn’t shy away from burning witches or throwing tea into Boston harbor or sending debtors to prison. Fred was no exception to this rule, and not unlike Bill Belichick in his days with Jets… he may have been cast off for a time, but Boston loves a winner… and Fred was a winner.

The Ice King Cometh 

After the war of 1812 had settled down…..

you know the war of 1812 right? the one that was just a big misunderstanding where the British burned the Whitehouse to the ground? Well, that war had an impact on the newly created international trade for ice. By 1815 everything had calmed a bit and Fred learned that in order to sell ice he had to –

  1. Become a pitchman for the product. Sure, prevention of meat spoilage was the most important market for his product but serving ice cold drinks in the Summer… that was the sizzle that sold the frozen steaks.
  2. Cut the ice more efficiently. Cutting by hand was labor intensive, he figures out how to cut and move the ice with horse-drawn sleds and it saved a TON of time. Now…. the horses added some FIBER to the ice occasionally, but it was just a small consequence of progress.
  3. Insulate Better. After losing so much ice shipping it great distances, Fred learned how to pack the ice better and insulate more effectively.
  4. Diversify. Shipping ice to a tropical location, saving some of the ice and the shipping back fruit preserved in ice…. that was a genius move.

All of these gains added up and by 1833 Fred was known as the “Ice King” when he shipped 180 tons of ice from Boston to Calcutta, India. The British elites in that far off place were able cool their drinks and their tempers.. we didn’t want another accidental Whitehouse incident after all.

But Fred was worried…. sure he dominated the natural ice trade, but there was a new technology that kept him up at night

The Machines of Cold

All the way back to the 1750’s (before Fred was born) inventors had been experimenting with the effects of evaporation of certain substances on the removal of heat. I can only imagine one of these men,  sitting in Philadelphia in the hot Summer of 1776… thinking about how his earlier experiments might cool Liberty hall, or at least their drinks as they hammered out a new country. Benjamin Franklin was one of the first to consider and experiment with changing the state of liquid to vapor to produce ice… but he certainly wouldn’t be the last.

The was inventor Oliver Evans in 1805 who talked about a method of continuous vapor compression to make ice produced by machines a reality… but he didn’t actually make it a reality himself. After all, making a few cubes of ice with a machine would be a novelty, a parlor trick in those days. Ice needed a market, a distribution system, market DEMAND. Fred was the one who created those things more than two decades after Oliver’s bright idea.

The Idealist

John Gorrie was not an inventor, it’s unlikely that he studied the papers of Benjamin Franklin or Oliver Evans. John was a doctor, born in the West Indies, raised in South Carolina and educated in a prestigious New York medical school in a time when medicine was a respected profession filled with misinformation and HORRIBLE practices. This is a time when writing a constipated patient a prescription for toxic mercury or soothing a colicky infant with narcotic “soothing syrup” was commonplace. So when John moved to steamy Apalachicola, Florida in 1833 t the age of 30, heaven only knows what sort of crazy nonsense he was doing to his patients unintentionally.


John Gorrie was a good man by all accounts who really cared about helping people get well. He had left a comfortable life in to deal with tropical diseases like malaria and yellow fever, brought into the Florida port town by sailors and spread by mosquitoes. John must have had to adjust to the oppressive heat and humidity of a Florida Summer and it was this HEAT that caught John’s attention.

By this time John had had some of Fred’s incredible ice in a drink and it sure made him feel better on a hot day. What if some of these illnesses could be helped… even cured if he could control the temperature the rooms of his patients with ICE.

His first experiments with using Fred’s expensive imported ice and it sure appeared to help lift the spirits of those in his care, but he just couldn’t get enough of the stuff to make a difference.  John’s theory was that diseases like malaria were a “vapor” carried in from the swamps and that by draining swamps and cooling, dehumidifying and ventilating patients rooms you could reduce or eliminate the disease.

So like most people who have a problem, they want to solve he began reading and experimenting and in 1844 John wrote about a machine he wanted to create that consisted of

“two double-acting force pumps, one for condensing, and the other for rarifying air and an air magazine or receptacle for condensed air. It may be placed in any part of a house or ship..”

Just to save you from looking it up, rarify means to “make less dense” or more simply to expand. In essence, John described a very simple vapor compression system that uses air as the refrigerant.

An Icy Reception 

It was the Summer of 1847 as the story goes, and a French nobleman Monsieur Rosan was celebrating Bastille Day in steamy Appilachicola. As the guests were commenting on the oppressive heat the nobleman rose and announced to his guests that they would be able to enjoy chilled wine, thanks to ice mechanically produced by doctor Gorrie and his prototype machine.

In 1851 John was granted a patent for his ice making machine, and as the story goes he also found a deep-pocketed investor willing to put up the money to make this prototype a commercial success. A Boston investor lost to history, a Boston investor who died before the deal was final.

It was then that the wheels of John’s ideas began to come off. In publications across the country, the articles would write of Dr. Gorrie and his folly, of how inefficient his machines were and how foolish the invention was… after all, the “Ice King” had already solved the problem by making ice available all across the globe.

Did Fred cause this trouble to fall upon John? Probably not. Did he help the process along the way? I would be willing to bet he did.

In the end, John and his friends would speak of how he was undermined by the ice lobby, by Fred and his ice gathering and shipping machine. In 1855 at the age of 51 Dr. Gorrie died a broken man, a man who in his own words had “had been found in advance of the wants of the country”, in other words, he accepted that he was a man before his time.

This story has no happy ending. There was no Clarence the wingless angel to show John the present that would have been without him or more appropriately the future that was. partially because of John and his contributions, a future all of us who are reading this work in every day.


Real change within industries and societies requires someone dogged and determined to take up the cause and push the idea to its destination. Inventors like Edison and Bell, industrialists like Rockefeller and Ford and even military leaders throughout history from Alexander the Great to Napoleon.

These people are applauded in retrospect for their brilliance and foresight, but to a man, their greatest asset was their determination. For every one of these “greats” whose names you know, there are thousands… Millions more, who have lived simple lives, working hard towards ideas they care about. People of determination who like John Gorrie and George Baily do the thing they were set on earth to do.

In the story of Mr. Potter and George Bailey or Frederic Tudor and John Gorrie, we clearly paint a hero and a villain. One man motivated by ego and greed, the other by altruism and vision. The fact is that every person has a bit of both in us. We all want to make a living, provide for our family and maybe buy a boat or a new truck along the way. It’s a noble thing to live a simple life and put some money away to enjoy, but don’t miss the opportunity to do the big thing that gets put in your path once or twice in a lifetime as well.

The fact remains that like John Gorrie we all play a part in the long, winding and noble story of our trade. You and I are a link in a chain back to Gorrie and Tudor and Franklin and to the people and systems we serve, we are more important than those men, dead and gone.

I leave you with a fitting (if a bit dramatic) poem, written for Gorrie 50 years after his death.

Give him a niche in the temple of Fame
Give him his place and hallow his name!
He, who in love for his suffering kind,
Lent them the use of his wonderful mind:
Pointed the way by unheard of device
To make in the Tropics the purest of Ice.

Give him a niche! May his name never die!
Build him a monument stately and high;
Who, in the ages, has equaled his thought?
Who for his fellows such solace has brought?
Think of the troubles his skill has allayed!
Think of the inroads on pain he has made.

Give him a niche and enshrine it with flowers!
Honor the man with divinity’s powers!
He who, no matter how sultry the day,
Drove from damp foreheads the fever away:
Pay quick a tribute that nobody shuns,
To GORRIE — greatest of Florida’s sons

Now go move some heat, and Merry Christmas.

— Bryan



We get a lot of questions about both evacuation procedure and TXVs so last week we produced videos on both topics including –

  • Before and after testing of piston vs. TXV
  • Using the Bluvac Measurequick app
  • Use of core remover tools for evacuation
  • flowing nitrogen process
  • creating an external equalizer port and much more

If you haven’t hit subscribe on our YouTube channel yet would you mind taking the time to do it today? it would be greatly appreciated. You can do that HERE 

P.S. – I will be at the Rectorseal booth 2545 in Chicago at the AHR conference on January 23rd at 2PM demonstrating the new Pro-Fit flaring tool. If you are at AHR come by and see me and sign up for a chance to win a free Pro-fit!

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