Lochinvar AMP 200-9 Installation, Commissioning, User & Maintenance Instructions page 10

6.3.1.2 Exposure height
The exposure height (3) of the reed contact is
very important to ensure the float switch works
correctly.
The exposure height is 14 mm. This setting
may not be changed!
With an exposure height of 14 mm the switch
point is approximately halfway along the stroke
of the float. If the exposure height is set lower,
then the switch point shifts upwards. If the
exposure height is too small the contact will no
longer connect even if the float is completely
above it. In this case the device will not come
into operation. If the exposure height is set lower
than 14 mm , then the switch point shifts
downwards.
This means that the contact will already connect
upon a small upwards movement of the float. If
the exposure height is set too high then the
Fig. Float switch
6.3.1.3 Checking the float switch
Switch off the feed voltage and remove the fuses
from the elements. In this way the control circuit
can be tested without the elements being put into
operation.
Drain the device until the water is definitely
below the float switch. If desired the float switch
can now be removed for visual inspection. Check
the resistance of the contacts with a multimeter
and check whether the switch point is situated
approximately halfway along the stroke of the
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contact is permanently closed and the safety
mechanism does not work. This means that the
elements can come into operation without there
being sufficient water present in the device. This
will lead to the elements burning out in a very
short time and short circuit and leakage. So
never change the exposure height.
The reed contact and the float must always be
vertical. The arrow on the clamping plate on the
front must point upwards. The float switch is
secured in the tank with nut (5). By loosening nut
(4) the float switch can be set vertically.
Nut (4) is sealed with an o-ring with respect to
nut (5). The float switch must be taken out of the
device as a complete unit for checking or
replacement. (The float cannot be passed
through the opening in nut (5).) For this purpose
the device thus has to be drained.
1. Float
2. Reed contact
3. Float housing (exposure height)
4. Nut
5. Nut
float. (For new contacts this resistance is
between 1 and 1.5 Ohms). Screw the float switch
back into the tank and place it vertically. Check
the exposure height. Close the door and connect
the feed voltage. The safety relays must not
come in. (The opening and closing of the safety
relays is clearly audible.) Now allow water to flow
into the device. If the water presses the float
upwards, the float switch closes the control
circuit and the safety relays will close. Then drain
the device once again. The lowering of the water
level will lead to the float switch blocking the
Installation, Commissioning, User & Maintenance Instructions