Crane Voce Media, Technical Manual, Page: 113 / 116

Technical Manual 105
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A FRESH APPOACH TO VENDING
11.11 Heater Circuit
The water temperature in the Main Boiler and the Pressure Boiler (B2C machines) is
controlled by a thermistor probe. This has a variable resistance – high resistance when
cold, low resistance when hot. The thermistor probe is in contact with the water and
continuously monitors the water temperature. At room ambient temperature the
thermistor resistance is approx. 3000 ohms. At 96°C the thermistor resistance is approx.
200 ohms.
Both Boiler Heating Elements are controlled by Solid-State Relays, which are in turn
controlled from the I/O Board. The Main Boiler Element is rated at 2.4kW, the B2C Boiler
Element is rated at 2.0kW.
Should control of the Heating Elements fail for any reason, both Elements are protected
by In-Line, Manually Reset-able Thermal Cut-Outs. These are positioned in the overflow
pipe of the Main Boiler (90°C), and on the casing of the B2C Boiler (115°C).