B3000 Brewer Water Flow Mechanisms
A schematic and legend showing the major components of the B3000 are provided (refer to page 8 and 9). The functions of these components are listed below.
1.Water filling – The B3000 is a direct plumbed machine. Municipal water is introduced to the unit through the inlet valve [X]. The supply water is then led to the cold water tank [BB] via the rigid plastic tube connected to the float valve [Y]. The cold water tank is allowed to fill approximately 16 ounces, (480 milliliters) and then the valve [X] is de-energized (closed) by the CWT float magnet proximity switch [Z] which controls the fill level. The proximity switch (located outside the tank) contains magnetically activated reed switch which is controlled by a float magnet (located inside the tank) that monitors the water level.
2.The Cold water Tank – The cold water tank [BB] functions primarily as housing for the secondary overfill protection device which is the float valve [Y] and provides the air gap necessary for back flow protection. If the normally closed inlet valve [X] were to fail open or otherwise be prevented from closing due to debris or CWT float magnet / switch failure, then the float valve [Y] would shut off the water supply once the water level rose to the level to activate the float lever. Back flow is prevented as the float valve inlet is approximately 1 1/4 inches (29 mm) above the over flow port in the cold water tank [BB]. The cold water tank also functions as the water supply reservoir for the brewing system. The water supply in the tank is fed through two check valve [M] and tubing to the two cold water pumps (CWP) [W] that supply water to the hot water tanks via the CWP elbow, CWP connectors, silicone tubing, multi-connector tee, and silicone tube.
3.The Hot Water Tanks – The water flows through the bottom tank and into the top tank via a seal assembly which includes two o-rings, a seal washer (between the o-rings), and the sealing cover. To allow the hot water tanks to fill, the vent valve [J] is energized (opened) to allow air to leave the system as the tanks are filled with water. Water delivered to the hot water tanks [TP] and [TB] is heated by the heating elements located inside the tanks. The only one heater at a time is allowed to energize and the heater in the top tank (brew tank) has priority. The water temperature is controlled by the thermistors [V] located in each tank. To control volume stainless steel conductive probes are used to sense the brew volumes of 4, 6, 8, and 10 ounces (120, 180, 240, and 300 milliliters). In order to brew the system is closed, vent valve [J] de-energized (closed) to allow pressurization.
4.The Puncture Mechanism – the mechanism [DD] consists of the K-cup holding and puncturing apparatus, a hot water delivery and brewed coffee path, and the hot water dispense valve [OO]. To brew coffee one lifts the handle to present the K-cup holder [AA]. A K-cup is placed in the holder and the handle is returned to the closed position. Upon closing the mechanism, the K-cup is punctured on the top first by the entrance needle [N] and then the bottom by the exit needle [P]. The holes created in the K-cup by the two needles are sealed about the needles by gaskets. Once the K-cup is in this ‘ready to brew’ state and a cup is placed on the drip tray, brewing can commence. To brew, the system is closed, vent valve [J] de-energized and the brew pump [G] is energized. The brew pump pressurizes the system to approximately 4 psi (27.6 kPa). The air is delivered to the top of the brew tank via a silicone tube by way of the filter tee [H]. The water in the brew tank is forced out of the tank through the integral brew tube [L] in the upper hot water tank cover. The water flows out of the top cover through a silicone tube to the entrance elbow which contains a check valve [M]. The water flows next trough the entrance needle, contacts the coffee grounds in the K-cup, and brewed coffee is delivered through the exit needle to the cup located on the drip tray.
B3000 SERVICE MANUAL | |
60-200807-000, REV C | 6 |