Today’s Talk...

1. Today’s Talk... • How does an absorption minibar work? • Temperature regulation – the Thermostat • General behavior of a minibar • Difference between an absorption minibar and a compression refrigerator • Installing a minibar • Verifying the behavior of the minibar • Identifying technical problems

2. How Does an Absorption Minibar Work? • The Cooling Unit provides the refrigeration. It basically contains: NH3, He and H2O under pressure. • The NH3 is the refrigerating component that passes through a cycle of evaporation, condensation, evaporation and condensation. • The system uses an electrical heater (resistance) and has no moving parts, making it completely silent. • To regulate the interior temperature, the thermostat turns the heater on and off.

3. Continuous Cycle Ammonia Absorption Refrigeration Water Separator Condenser Evaporator Absorber Boiler Absorber Tank

4. Continuous Cycle Ammonia Absorption Refrigeration Ammonia vapour rises and at the Water Separator the excess water runs back down At the condenser, the vapour condenses into liquid ammonia Liquid ammonia then flows into the evaporator, where the helium lowers the pressure making the ammonia evaporate and absorbing heat, lowering the inside temperature of the Minibar The helium and ammonia then pass to the absorber where they mix with the weaker solution that reabsorbs the ammonia, completing the cycle! Strong ammonia solution passes from the tank, and is heated at the Boiler

5. Thermostat - The Temperature Control Device • The thermostat is the device that controls the inside temperature by turning the heater ON or OFF • A sensor inside the minibar informs the thermostat of the temperature • EMS minibars are equipped with an ON-OFF electronic thermostat that has 3 different temperature settings • If conditions are adequate, the resulting average temperatures will approx be 2-3, 6-7 or 9-10ºC

6. Thermostats in the Market • There are 3 major types of thermostats in the minibar industry: • Electro-mechanic • Electronic ON-OFF • Electronic PID / Fuzzy

7. General behavior of an empty minibar - ON-OFF thermostat After the minibar is connected, it takes over an hour before the temperature starts to drop Under normal conditions, after 5 hours the inside temperature should reach normal working temperatures If the temperature is too low, the thermostat turns off the heater, if it is too high, it turns it on, generating these uniform cycles Defrost: 1 hour per day, the minibar is turned off. If the inside temperature reached is too high, it automatically turns itself on.

8. General behavior of an empty minibar - PID – FUZZY thermostat The only difference is the lower fluctuation of temperature, as the heater is controlled by turning it on and off at greater frequency The lower fluctuation of temperature does NOT have a positive impact on beverage temperatures!

9. Differences Between an Absorption Minibar and a Compressor Refrigerator

10. Installing a Minibar – Ventilation! • The most frequent problem is deficient cooling due to insufficient ventilation • Follow the instructions in the User’s Manual

11. Verifying the Behavior of the Minibar • Temperature Data Recording Systems - Know exactly what is going on! www.fouriersystems.com

12. The Minibar is “not cooling” Identifying Technical Problems Is it cooling at all? Yes No Is the Cooling Unit completely cold? Verify ventilation No Verify ambient conditions (sunlight etc) Verify voltage supplied at the wall Verify voltage supplied at the wall Yes Verify that the Minibar is in a levelled position Verify that the minibar is plugged in Verify that door closes completely Verify that the Minibar has been running for enough time Verify mains voltage Verify cooling unit is not blocked (Some parts hot, other cold, due to obstructed flow) Verify connections of the thermostat and heater using a multimetre