Armfield PCT40 - Freeing a Seized Hot Water Pump

Routine Maintenance
51
Drain the moulded channel in the plinth via the channel drain valve located in the
recess at the left hand end, then unscrew the drain valve and remove it.
Unscrew the six fixings around the periphery of the plinth top.
Carefully raise the front of the top moulded section – the two sections are hinged at
the rear. Unclip the prop that is located inside the front of the bottom moulded section
then support the top section centrally at the front using the prop. Ensure that the prop
is properly located in the appropriate recesses.
The electrical circuits inside the bottom moulded plinth section are accessible for
working on.
A circuit diagram showing the mains and DC electrical circuits inside the plinth is
included in the Electrical Wiring Diagram
to assist in fault finding.
Re-assembly of the top and bottom moulded plinth sections is the inverse of the
above instructions.
Freeing a seized hot water pump
In normal use the hot water pump should not require any routine maintenance and
running should keep the gears free from scale due to hard water etc. However, if the
water is contaminated with flakes of hardness or dirt particles then the gears inside
the pump might seize because of the small operating clearances that are necessary.
If the hot water pump does not operate when switched on it then it will be necessary
to check the pump as follows:
Disconnect the electrical supply to the equipment.
Disconnect any flexible tubes connected to the gear pump to minimize loss of
water when the pump is opened.
Remove the rectangular end cover from the head of the pump by unscrewing the
four cap headed screws using a hexagon wrench (Allen key). Any water draining
from the pump will drain into the top of the plinth.
Inspect the gears, cover etc for any contamination and clean as necessary but do
not use any harsh abrasives or volatile solvents on the plastic gears or the
anodized aluminium body.
If it is necessary to remove the plastic gears take care not to damage the gears
or to lose the drive key inside the driven gear. If the gears are stubborn to remove
then a pair of tweezers or similar tool may be used to extract the gears by
grasping one of the flutes.
When the pump is clean replace the gears ensuring that the drive key is correctly
located inside the slot in the driven shaft. Ensure that the gears are free to rotate
before replacing the end cover.
Ensure that the sealing gasket is correctly located in the groove on the end face of
the pump body then replace the end cover and secure it using the four screws.
Reconnect the flexible connections and reconnect the electrical supply. Ensure that
the hot water vessel is full with water then check satisfactory operation of the pump.