Amount Of Water; Flood Protection; Heating; The Heating Element - Fisher & Paykel DishDrawer DD24D Series Service Manual

599735A
3.6.3

Amount of Water

The tub fills with approximately 2.5 litres / 0.8 US gallons of water, almost level with the base of the
spray arm. Once this level is reached, the wash pump (which has load-sensed the fill via the
electronics) becomes primed and pumps the water through the spray arm causing it to rotate. The
load on the wash pump is constantly monitored throughout the wash cycle and the water level
adjusted if necessary. If the wash pump loses prime, the electronics will top up the water level by
opening the fill valve for approximately 5 seconds. It will do this up to 3 times before carrying on
regardless.
3.6.4

Flood Protection

A flood sensor mounted on the side of the mains filter housing provides flood protection. If a flood
is detected, the drain pump will run and an F1 fault code will be signalled to the customer
3.7

Heating

3.7.1

The Heating Element

The heater plate is a porcelain enamelled steel plate with a thick film resistive circuit printed onto
the dry side. A gravity thermal fuse is mounted on the heater plate in series with the heating
element. A large dropping resistor is also printed onto the heater plate which forms part of the
controllers power supply. The element is clamped in place by a locknut and supports the motor at
the base of the tub.
3.7.2

Heating the Water

The heater plate is positioned beneath the filter plate. A flow through water heating system is
created during the wash cycle by allowing water to flow through the filter plate, over the surface of
the element and into the wash pump.
3.7.3

Maintaining the Temperature

A printed circuit board with a temperature sensitive thermistor is mounted on the heater plate.
Sensor components are unserviceable and if they fail a new heater plate is required.
3.7.4

Overheat Protection

The heater plate is only activated during the wash cycles.
temperature is monitored by the thermistor. If a failure occurs with the electronic control of the
heater plate, overheat protection is effected by the thermal fuse on the heater plate.
The thermal fuse consists of a gravity fuse in series with the water heater track that will melt at a
relatively low temperature, 268 – 302
This fuse does not isolate the dropper resistor and so does not remove power from the controller.
3.8

Motor and Heater Plate Locknuts

There are two locknuts holding the heater plate and motor housing assembly into the base of the
tub to form a watertight seal. They do this by compressing two seals, one between the heater
plate and tub, and the other between the heater plate and the motor assembly.
When reassembling the motor, it is important that a motor shim is placed between the inner locknut
and the inner element seal.
The outer locknut has locations that hold the drain hose, fill hose and wiring loom in place.
Another function of the larger outer locknut is to support and clip the wiring cover.
O O
C (514 – 576 F) and disconnect the power to the element.
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It is not used for drying. The