B-2 Hydronic Heating and Cooling Generating Equipment Introduction

The following terms will be used throughout this section. A complete list of terms for this section can be found in the Glossary.

• aquastat: A device used in heating systems to control the temperature of the water. It works like a thermostat but specifically for water, turning the boiler on or off to keep the water at the desired temperature. (Section B-2.1)
• authority having jurisdiction (AHJ): An organization or person responsible for enforcing safety and building codes. They make sure that buildings and structures follow the law and safety standards, such as proper electrical wiring and fire safety measures. (Section B-2.2)
• backflow preventer: A device installed in plumbing systems to prevent water from flowing backward into the potable water supply. (Section B-2.2)
• dedicated branch circuit: An electrical circuit that supplies power to only one specific piece of equipment or appliance, without sharing the circuit with other devices. (Section B-2.2)
• floor drain: A plumbing fixture installed in the floor of a building, typically found in areas like basements, bathrooms, or utility rooms. Its purpose is to remove excess water and prevent flooding by directing water into the building’s drainage system. (Section B-2.1)
• header: Boilers, depending upon their size, have one or more outlet tappings. The vertical steam piping from the tapped outlet joins a horizontal pipe called a header. The steam supply mains are connected to this header. If the boiler has more than one outlet, it is important to remember to pipe the headers with swing joints. This will help alleviate any stress on the boiler when the header heats up and expands. (Section B-2.1; Section B-4.2)
• housekeeping pad: A raised concrete platform on which mechanical equipment, such as a boiler, is mounted. (Section B-2.2)
• input (boilers): the amount of energy the boiler consumes in order to produce heat. (Section B-2.1)
• low-water cut-off: The job of the low-water cut-off is to shut off the burner should the water level fall to an unsafe level. The boiler manufacturer determines this level, but it is usually within one-half inch of the bottom of the gauge glass. (Section B-2.1)
• output (boilers): The amount of energy that is actually transferred to the medium being heated (water, heating fluid, glycol, etc.). (Section B-2.1)
• passive (solar water heating) systems: Solar water heating systems that move water or heat-transfer fluid without pumps. There are two types of passive systems: Integral collector storage (ICS) and thermosiphon systems. (Section B-2.1)
• potable water system: A water supply system that provides water safe for drinking and other domestic uses, free from harmful contaminants. (Section B-2.2)
• push nipples: Small connectors used in boilers and heating systems to join sections of piping together securely. They allow for easy assembly and disassembly when maintaining or repairing the system. (Section B-2.1)
• thermosiphon systems: This type of passive solar watering heating system relies on convection created between the fluids in the tank and in the collector. The fluid in the collector becomes less dense and rises into the tank above, while the denser fluid in the bottom of the tank falls through piping into the bottom of the collector to be reheated. The fluid to be heated is circulated through a separate path within the tank (heat exchanger) where it absorbs the heat created and returns to the building for use. (Section B-2.1)
• tridicator: A device that measures and displays three different things at once: pressure, temperature, and altitude (or level) of a liquid in a system. It’s commonly used in heating systems to monitor these conditions and ensure everything is working properly. (Section B-2.1)
• waste heat (or waste energy): Energy that is produced but not used efficiently, often escaping as heat during processes like running machines or producing electricity. Instead of being used, this energy is usually lost to the environment. (Section B-2.1)