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7.7 Tank heaters
Depending on specification, your motorhome
may be fitted with 12v tank heaters, designed to
prevent or reduce instances of freezing water in
fitted water tanks.
If tank heaters are fitted, they can be turned on
via the control panel feature above the entrance
door (see 8.7). Turn this feature on when the
external temperatures are low, and the tank
heaters will then turn on and off automatically.
Before heating each tank the system will check
that the water level in each tank is at the 1/4
level or higher (the heaters will not operate
if the tank is ‘empty’). If the water level is
appropriate, the heaters will then switch on and
off depending on temperature.
As the tank heaters check the water level in each
tank, the fresh and waste water tank heaters
can operate independently, for instance use of
frost protect feature while the fresh tank is full,
but waste tank is empty, would only result in the
operation of the fresh tank heater.
It is also possible to use the tank heaters en-
route, i.e. while driving. With the control panel
ON, turn on the tank heaters as described above.
While the engine is running the control panel
cannot be operated, however, the tank heater
circuits will remain ON.
Please note that the heating elements use a 12V
supply. With the engine off, and if used without
a mains hook up and charger operating, then
leisure battery power consumption will be
increased (see 7.20 for more information).
7.8 Water level sensor & cleaning
Principle
The sensors fitted to Swift Group motorhomes
are mounted on the water tanks, and link to
the power supply unit, via a pre-fitted wiring
harness. These can be in the format of rod, stud,
or float switch types.
The rod type sensors consist of a number of
stainless steel rods, at different positions,
suspended from the top surface of the tank
and immersed in the water contained within
the tank. They use the conductivity of water,
between the rods, to provide a reading to the
control unit.
The stud type sensors are similar, except they
are mounted in the side of the tank at differing
heights. As with the rod type, the conductivity
of water between the studs is used to provide a
reading.
A final, float type, is also mounted in the side of
the tank. These multiple switches are ‘on’ or ‘of’
depending on the level of water within the tank,
relative to their height on the side of that tank.
The rod and stud sensors are ‘digital’, in that
while the conductivity (resistance) value
can vary, the power supply unit will register
any conductivity between the rods or studs,
indicating water present. Normally, even if the
rods or studs are dirty, providing the they are
not bridged by a foreign object, a circuit will still
be delivered back to the control unit and a water
level displayed.
Sensor cleaning
The first step, in case of fault diagnosis, is to
clean the inside of the tank and/or sensors.
False water level readings at the control unit can
be caused by calcium build-up or foreign objects
within the tank bridging the rods or studs, or,
preventing the movement of float switch.
Your dealer will be able to assist in the purchase
of cleaning solutions for the water tanks, those
products being safe for use in drinking water
supplies, and not containing chemicals which
could damage the stainless steel components
within the water system.
CONNECTING SERVICES
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