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An Introduction to Brewer Basics from the Coffee Technicians Guild


I am convinced that coffee brewers come with their own gremlins. If by chance you don’t know what a gremlin is, there are numerous Bugs Bunny cartoons that can explain what they are.

I’ve had service calls that have frustrated me so much that I felt like William Shatner from the Twilight Zone Season 5, Episode 3 called “Nightmare at 20,000 Feet,” where he ends screaming “I realize what this sounds like. Do I look insane?” Ultimately, there was a gremlin on the wing of the plane.

Simply speaking, coffee brewer systems are composed of three interacting systems: the water system, the heat system and the dispensing system.

  1. The water system deals with delivering water into the boiler or tank.

  2. The heat system heats the water to an accurate temperature to extract brewed product.

  3. The dispensing system controls the dispense or spray of water over the ground coffee to obtain a delicious coffee product.

 Each system has common components that interact with each other. Each component works with the rest of the system to draw water, heat water and brew coffee.

Water system

  • Level Probe: Uses a low voltage signal to determine the water level in the tank.

  • Level Control Board: Interprets the signal from the level probe and activates the inlet valve as needed to fill the tank.

  • Inlet Valve: Opens with a signal from the level control board to fill the tank and closes when the water level reaches the level probe. 

Heating system

  • Control Thermostat: Controls the heating system based on temperature. When the water in the tank is below the set temperature, the thermostat closes to indicate that heat is required. When the temperature reaches the set point the thermostat opens to stop heating.

  • Triac and Circuit Breaker: A triac allows power to the tank heater. This occurs when the thermostat calls for heat. The control board picks up the signal and power is allowed to flow through the triac.

  • Relays and Contactors: A contactor is a set of contacts that are opened or closed when energized by current.

  • High temperature cut off: The function is to break the current flow to the heating elements in case of a low water condition causing the heating elements to reach a high temperature when they are exposed, out of the water.

  • Elements: Heating elements are made of electric filament and their role is to heat water for the coffee.

Dispensing system

  • Brew Switch: One switch functions to get power to the board, and one switch functions to activate the timer when it is pushed in.

  • Timer: the brew switch activates the timer. At the same time, it energizes a solenoid valve to open and allow water to flow from the heating tank to the bypass and spray head.

  • Brew and Dump Valve: The valve communicates with the timer.

In an upcoming series on brewers, we will identify what parts are used in each system, how they operate, and then close with troubleshooting.

[Editor’s note: This article is appearing as part of an unpaid editorial collaboration between DCN and the Coffee Technicians Guild. It was originally published in the CTG blog and is republished here with permission. The Coffee Technicians Guild (CTG) is an official trade guild of the Specialty Coffee Association (SCA) dedicated to supporting the coffee industry through the development of professional technicians.]