Description Of Components - Bosch SHI4302 Manual

V. Theory of Operation
V. Theory of Operation
VB.

Description of Components

VB. Description of Components
Circulation pump -- Unlike many dishwashers, Bosch dishwashers use separate circulation and
drain pumps to reduce noise, vibration, space and energy usage. The circulation pump circulates
water from the sump into the spray arms.
Drain pump – The drain pump drains water from the dishwasher. Being a separate pump, it is much
smaller and uses much less energy than a single circulation/drain pump used on other dishwashers.
Impeller – This part of the circulation pump is what drives water throughout the dishwasher. It uses a
precisely manufactured ceramic disk to reduce friction, yet prevent water leaking. This is the part to
replace in rarely used dishwashers if pumps don't turn.
Flow-through water heater – Unlike most dishwashers, that rely on exposed heating elements in the
bottom of tanks, Bosch dishwashers use flow-through water heaters (that heat ~ 2ºF/minute). This
saves space and allows Tall Tubs (see below), where full-sized plates can be placed in both upper and
lower racks.
NTC – Stands for "Negative Temperature Coefficient". This temperature sensor in the water heater
provides accurate water temperatures. Its called a "NTC" since its resistance goes down as the water
temperature goes up.
Thermostat – Temperature sensor (and switch) used on older mechanical dishwashers. They open
when temperatures are reached.
Control module – The brain of electronic dishwashers, it receives water temperature values and
controls the entire wash process. It also contains the test program to help diagnose dishwasher
issues.
Display module – A separate electronic module with a digital display used on some models.
Water inlet valve – Water valve which turns on and off to allow water into the dishwasher.
Water inlet system (with fill switch and diaphragm) -- It insures dishwashers fill properly at various
incoming pressures. It uses a air pressure diaphragm and fill (micro) switch to alert the dishwasher
control module when the proper amount of water has filled the dishwasher.
Float switch – This safety feature shuts down the dishwasher and starts the drain pump if the
dishwasher has gotten excessive water in the base or has overfilled. The drain pump empties out the
sump and hoses, not the base (I.e. the drain pump isn't a base bilge pump).
Condensation drying – This feature saves energy and enables Bosch dishwashers to have Tall Tubs
– the tallest tubs in the industry, allowing full-sized plate to be placed in both upper and lower racks.
Bitumen insulation around doors and tanks holds heat inside tanks, which forces water vapor out of
tanks before it can condense onto dishes. The area around the condensation tube exit isn't coated
with bitumen, providing a cold zone for water vapor to condense (instead of on dishes).
Condensation tube – This is part of the genius of condensation drying. It carries moisture out of the
tank while condensation drying is occuring.
Detergent & rinse-aid dispenser – This dispenses detergent and rinse-aid at just the right times. In
older dishwashers (service indexes UC/06 & UC/11), it attached to the condensation tube (in the door).
Aqua sensor (Sensotronic) – This sends a beam of light through water in the heater and measures
how clean the water is. Depending on water cleanliness, rinses are omitted, saving time & energy.
Microfilter and filter screen – Unlike other dishwashers, the water in Bosch dishwashers is
continuously filtered (100% of the time). The filter screen traps large food chunks while the two or
three stage microfilter (depending on model) filters out small food particles.
Softer bearing – Used to describe circulation pump mounting system using rubber straps to further
reduce noise and vibration (on UC/11 & later models). Sumps and heaters were changed as well as
circulation pumps. Older models (UC/06, UC/07 & UC/09) had pumps mounted on rubber bushings.
Tall tubs – This distinctive feature allows full-sized plates (~ 10") to be placed in upper racks. The
tallest tanks in the industry is made possible by separate pumps, condensation drying and good use of
space in the dishwasher base.
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