“Heat”
Cold winter nights are a part of life in Colorado. The relief of a warm room on tingling toes and fingers is one of the great pleasures experienced by those that inhabit cold climates. As a small child I used to huddle around the fireplace with my family and lose myself in the warmth and serenity of the moment. As I got older and my schedule got busier, nights around the fireplace slowly drifted into the background. A new source of heat sustained my families busy lifestyle. I never so much as questioned where this magical heat came from. I suppose I just assumed that indoors are naturally warmer and buildings were created for just such a purpose. While my ignorance slowly disappeared as natural gas prices and insulation values became a nightly conversation around my families dinner table, I never truly attempted to seek out nor did I really care how heat was created. It was just one of the many facets of life I merely took for granted.
This changed however in May of 2005. After a less than admirable two years at college my parents decided some time off of school would be beneficial for me. Having half of a Bachelors degree and no money, I decided to join the Plumber’s Union. I figured snaking toilets, and cleaning sinks would not only be great fun but the money would be good enough to justify the work. However, as time passed and I had installed my fair share of waste pipe, I began to focus on home heating systems. Boilers soon became my niche. These incredibly expensive and time consuming systems are a quandary to many people. The finished product of copper, steel and wires often created glazed looks on many of the individuals faces who had purchased them. While most people can easily intellectualize the general idea of how a boiler heats a home, the intricate workings tend to illicit the same confused reaction I have when viewing the circuit board of my computer.
The main idea of a boiler is to send hot water around a building. Through transduction this consequently heats the air with which the water comes into contact. This broad description is better understood through a more intrusive and mechanical examination. A boiler is basically an insulated box. As our bodies contain the blood that warm and feed our systems, the boiler is the site of water heating and storage. In many of the new High efficiency versions, the boiler is much more than just a hot water holding tank. It contains the electronic acuteness and accuracy of the computers we use in our homes today. As the brain acts as a response system for the many connected parts of our bodies, the highly intelligent circuit board systems of these boilers are constantly regulating and responding to a multitude of changes. Water Ph, Temperature, pressure, and exterior wind variances are just a few examples of the monitoring that occurs within these intelligent boilers.
While most systems are powered by natural gas, electric systems do exist. These both follow the same procedure. As sub-180 degree water passes through the belly of the boiler, a pillow of gas bombards a pilot light and creates a large sustainable inferno of fire. The energy from the fire is stored as heat in the molecular structure of the water. Many large boiler systems contain ethylene glycol as an additive to help the water retain this heat as it’s pumped around the building.
While the blood within our bodies is constantly being pumped around by our heart, a boiler only pumps its water when absolutely necessary. That little device hanging on the walls of our homes that is often overlooked or taken for granted, is the device used for alerting the boiler that it’s time to start pumping. The thermostat, which for many years of my childhood served as a lecturing point for my father, acts as the eyes to the boiler. While simple in purpose, these little devices have become more complicated with time. Many contain miniature circuit boards of their own in conjunction with the computers on the boiler itself. Once the message has been sent to the boiler to start circulating its pre-manufactured hot water, a whole series of events ensue.
While there are numerous valves and drains associated with these systems, only a select few of these external components are worth noting. Like our brain controls the timing of our heart beat, the thermostat relays information to the boiler to start its own rhythmic pumping. As the pumps push 100’s of gallons of 180 degree plus water throughout the building or home, it’s the role of the control valves to decide which rooms to send the water to. When a person seeks out a warm room in an effort to restore heat to their fingers and toes, it’s the role of the brain to send their warming blood to cold appendages. This is in an attempt to restore the body to its preset thermostatic temperature of 98 degrees. The hot boiler water likewise is sent to cold rooms in an attempt to restore the rooms to their preset thermostatic temperature.
I recall the first time I went to donate blood, a friend telling me the dangers of such an endeavor. He told me that on occasion these low trained blood drawing facilitators would accidentally pump an air bubble back into an individuals vein. Once this air bubble reached their heart it would kill them. Whether this is true or not, it follows the idea that air bubbles in your blood presents a dangerous situation. The same is true for a boiler system. Air Locks, a noisy system, or inefficiency are all the result of air in a system. While a process called purging is initially used to remove the air, a device called an air scoop is installed to constantly remove air from the system. On close examination, an air scoop looks much like a honeycomb that swirls the water, agitating it enough to create air bubbles and promptly removing them via an air relief valve.
Three other consequences occur as a result of constant heating and cooling of water. These are somewhat obvious if you consider them. First, burning natural gas creates fumes. Just as your car has an exhaust or your body has lungs, a boiler contains both an air intake and an air exhaust. The individual specifications for how to build each of these are regulated by numerous boring pages of technically written code - too dry to try and commit to memory or bore one with in this essay. Basically when natural gas is burned it creates carbon dioxide, carbon monoxide and water vapor. These byproducts must be vented outside through a series of ducts.
Obviously as water is heated and cooled it expands and contracts. Inevitably this creates varying pressure within the closed boiler system. Just like having high blood pressure can create an array of health problems, a buildup of water pressure inside a heating system can create plumbing problems. This pressure buildup reminds me of a person I once met whom had blood pressure so high he began to bleed out of his gums. While certain medication is administered to lower blood pressure in the body and avoid complications such as this, an expansion tank is installed to counteract the pressure in a boiler system. An expansion tank absorbs this extra pressure by use of a rubber bladder enclosed in a steel case. As pressure builds up in the boiler and its adjoining pipes, it pushes on this rubber bladder, equalizing out the pressure.
The final problem that must be overcome in a system that is constantly heating and cooling water is water loss. As water is heated to 180 degrees much of it is evaporated through the exhaust as steam. A device called a water fill valve is installed to replenish this lost water. To prevent air from replacing this lost water supply, a fill valve must work quickly to refill the system. This is accomplished by a valve set at the same predetermined water pressure as the boiler system (12-15 P.S.I.). When a drop in water pressure occurs, a diaphragm inside the fill valve relaxes and allows fresh water to replace the void.
So I continued to install these boilers systems in individuals homes. I met many people that held the same unawareness of the workings of their heating systems as I had once held. The children of the customers often times had many questions and their elders seemed to hold a reserved awe at the finished product. The visual display of shiny copper, numerous pumps and the controlled mess of wiring often times resembled more of an art project than a technical undertaking. My found appreciation in a subject I once disregarded as magic and later as a modern convenience, has inspired me to ask more questions of the mechanical world I live in. While mechanical engineering isn’t my current field of study, its principles are what inspires my present search for knowledge.
