Boiler Basics: How a Century of Innovation and Energy Crisis Shaped Modern Heating
An overview on how the past informs today’s boiler solutions
BOILER: From oil-fired giants to smart, AI-driven systems, boiler technology has come a long way since the 1972 energy crisis.
It is always good to take the time to refresh oneself on boiler basics, beginning with boiler technology that has been around for over a hundred years and technology that changed significantly when the 1972 energy crisis occurred in America. At that time, boiler manufacturers had to acknowledge that things were going to change as the country faced an oil embargo and oil became limited. Building owners needed a more reliable source of fuel to power their boilers and, simultaneously with this fuel shortage, energy conservation evolved, impacting how design engineers looked at alternative sources to heat buildings.
Before 1972, commercial, institutional, industrial, healthcare, and academic facilities probably had oil-fired boiler(s) on site. The boilers were usually fire-tube type or cast iron sectional type. On larger, more complex, and campus sites, #6 and #4 oil were often used to generate steam heat, which would be converted to hot water heating at times through steam-to-hot water heat exchangers.
Soon, the boiler industry was providing design engineers with numerous alternatives to this building standard. There were now options that resulted in less-polluting types of equipment, including #2 oil, natural gas, waste heat units, and electric units. Later on, condensing boilers were introduced, eliminating the need for a chimney stack.
The control technology changed from electric/electronic and pneumatic-electric controls to digital control strategies. Today, this technology can include artificial intelligence to assist in managing the boiler and its associated components, such as pumps.
For heating, ventilating, and air-conditioning (HVAC) service contractors, boiler basics go beyond providing the optimum boiler replacement, addition, and/or new installation for their clients. Here are some important issues, concerns, and features not to overlook:
- Primary fuel and its availability and reliability
- Number of units, e.g., one boiler at 100% capacity with no stand-by unit, two units sized at 60% capacity each, etc.
- Stand-by fuel, e.g., dual-fuel burner(s)
- Boiler operating pressure configuration, e.g., a low-pressure unit carrying the full load, most of the system's low-pressure load with individual mini-high pressure boiler(s) for isolated applications, such as serving sterilizer(s)
- Unit efficiency
- System operating pressure, e.g., low pressure, medium-high pressure
- Certification of boiler operator based on the equipment type
- Equipment first cost
- Equipment installation cost
- Operating cost (utility cost and preventive maintenance cost)
- Equipment life cycle in years
- Physical fit within the building (unit footprint)
- Structural ability to carry the load of the unit into the building and its eventual location
- Ability to rig the boiler into place
- Auxiliary power requirements
- Accessibility around the equipment for servicing, e.g., tube cleaning, tube removal, etc.
- Environmentally safe chemical treatment of the energy source (steam heat or hot water heat)
When it comes to boiler basics system control strategy, the options can be endless depending on the application and the other equipment that make up the entire system, e.g., primary-secondary pumping variations, etc. Also, energy conservation retrofits of existing boiler equipment can offer opportunities to redesign the installation based on “hindsight being 20/20” and reviewing operating utility consumption records.
Other boiler system applications can also include master plans for building and/or campus expansion utilizing a central plant distribution to multiple buildings or a multi-building campus with decentralized boiler plants, e.g., one per building.
For the mechanical contractor providing maintenance of boilers and seasonal startup and shutdown, reviewing the 17 basics above and taking a design-build initiative with the company’s in-house design engineer, or partnering with a design engineer consultant, can provide a proactive “Win-Win” situation: a win for the client with a return-on-investment retrofit of their boiler plant/system, and a win for the mechanical contractor who provides an annual service contract to the client.
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