It should come as no surprise to anyone that I am deeply passionate about what I do. Granted that it is incredibly fun to sell and work with HVAC equipment, but I am also fascinated by the history of heating. When you think of the history of something like heating you automatically assume this is a human necessity and therefore must have been around since the dawn of time and in theory you would be correct. An open fire of some sort was the primary source of heating for humans for literally millions of years. And what an impact that fire made. You still see them today more as a décor addition but still functional in their abilities to provide heat and comfort to those around it.
So, our ancestors understood fire and it was taught through generations that this thing called fire is hot. Hot is great when outside is cold. Keeps you from dying which is great. The idea of the open fireplace remained as the leader of the heating pack for a very, very long time. Sure, there were other iterations of fire, and we started to do good things with the heat residuals “smoke” from fire for archaic central heating systems, but it was still, for the most part, based on an open pit fire. How much fire did you need? Until you were warm. Need more heat? add more wood. Need less heat? let the fire die down. Not exactly scientific but it kept people alive. And that my friends is a key note to remember when it comes to heating, it’s not exactly scientific or at least its humble beginnings were not. It all came from when we were talking about heat, we didn’t really have any way to measure that heat or the actual temperature.
Temperature had to come first and where does temperature come from? I’m going to tell this story the way it was told to me so there is likely going to be some embellishment but that’s what a great story has.
The first recorded “thermometer” was said to have been created by Galileo around the late 1500’s and he called it a thermoscope. It was a crude device that worked off the principle of alcohol expanding while heated and if it was contained inside of a glass tube you could see how much the alcohol had expanded. The next logical step was to put lines on the side of the glass tube and call them degrees and in this case, it was degrees Florentine as it was invented in Florence. In a roundabout way, the idea of degrees was made up on the spot. The problem with this thermoscope was the accuracy was a wild variable that depended on a number of different criteria such as the strength of the spirit used which made it not very reproducible.
Let’s fast forward a bit two hundred years to the early 1700’s when a young Gabriel Fahrenheit was experimenting with thermometers due to their high demand for an accurate one. He did experiments with mercury which was a much more accurate fluid for measuring temperature and Gabriel’s first experiments were recorded in degrees Romer (not to be confused with Réaumur as that’s another tale for another day). Romer, a temperature scale still used today in some European countries, was coined by Ole Romer. He named it after himself, which was the thing to do if you wanted to get your name in the history books. As Gabriel Fahrenheit did his experiments, he borrowed heavily from the Romer scale at first. It was his thermometer’s unique way of using mercury that made it so accurate, and it wasn’t until his thermometer really took off that he made some heavy changes to his scale to make it more readable and called it degrees Fahrenheit. There is much more to this story too, but I want to take to you the ultimate nonscientific discovery that happened about 100 years later.
Entering the story is Thomas Tregold. Thomas was an engineer by trade but dabbled in lots of different things. One of the things that fascinated him greatly was this new-fangled invention of a kettle type boiler that placed water above a firebox and created steam. Now, steam as a method of power had been around since at least the early 1600’s but it was primarily used for power as it was a relatively dangerous device. Huge pressures and extreme temperatures kept this power source out of homes for years until this kettle type device came around and even then, these things used to blow up all the time. It was very convenient tough, if you could keep them in one piece.
Tom lived with his uncle in London for many years while working at the family architectural firm and during that time, Tom wrote a few books and coined a few terms. One of these terms comes from his book in 1824 called “Principles of Warming and Ventilating Public Buildings” where is used the term British Thermal Unit defined as the amount of heat energy required to heat one pound of water one degree Fahrenheit in one hour. Fahrenheit being the most common unit of temperature measure in England at the time. Tom wrote this book while doing experiments on a steam radiator in his uncle’s basement. Although the actual experiment he used seems to be lost to history, the legacy of that term British Thermal Unit caught on. What is so fascinating is that none of these things, degrees in temperature or BTUs exist in nature. They weren’t waiting to be discovered. They were made up as we went along.
A few very important things came from the BTU. The first of which was a way for boiler manufacturers to rate their boilers and in doing that created categories which helped the consumers compare prices for equally sized units. This kept the prices in check and helped expand greatly the home central heating world.
It’s fascinating to me that a unit of measure that has been such a huge part of my life and career was created by some guy in his uncles’ basement. I thought for something as concrete and powerful as the BTU must have been etched in stone from days long forgotten and past down through generation to generation or it was established by a committee of the smartest minds in the world. Nope, Tom in his uncles’ basement one day decided what it is, how it is measured and what it is going to be called.
The BTU has more history too. A history that has been built upon it since its beginnings and even to this day there are still some arguments as to how to define it, but that doesn’t really matter anymore. The phrase is coined and is now a unit of measure used all around the world.
So, the next time you look at the size of a boiler or chiller or anything that measures its output in BTU’s, remember that this beautiful little unit would not exist without the steam boiler. From Galileo to Fahrenheit to Tredgold, they all had one thing in common, they made it up as they went along. That’s the beauty of heating and a reminder not to take all the scientific mumbo jumbo too seriously.
The Story of BTU by Matthew Reid, director of heating department
