Potterton Promax Store 24 Installation And Service Manual page 43

4.15 Replacement of Immersion Heater and Immersion Heater Combined Thermostat/Thermal
Cut-out
The cylinder must be fully drained prior to removing the immersion heater. Refer to Section 2.8 for the procedure to drain the
unit.
1. Important: Ensure ALL power supplies are isolated before starting work on the boiler.
Perform the actions detailed in section 4.1 General Access.
Note: only the two lower front panels need be removed for this servicing action, follow instructions 3 and 4 for how to
remove these panels.
2. Remove the immersion heater cover by removing the securing nut and pulling the cap away from the cylinder.
3. Disconnect the electrical supply cable from the thermostat and the earth post assembly. Remove the thermostat from
the immersion heater by carefully pulling outwards. DO NOT twist the thermostat as damage to the connections to the
immersion heater may occur.
4. To remove the immersion heater unscrew the brass backnut using the key spanner supplied with the unit. Retain the
backnut. Over time the immersion heater gasket may become stuck to the mating surface. To break the seal insert a
round bladed screwdriver into one of the pockets on the immersion heater and gently lever up an down.
5. Withdraw the immersion heater from the cylinder.
Note: the immersion heater is curved downwards 90 degrees to reach the base of the cylinder. When removing, the
head of the immersion heater should be tilted towards the floor for ease of withdrawal.
6. Insert the immersion heater into the boss ensuring the right angled element hangs vertically downwards towards the
base of the unit. Push the immersion heater mounting plate into the boss so the gasket seats on the flange at the
base of the boss. It may be helpful to support the immersion heater using a round bladed screwdriver inserted into
one of the pockets on the immersion heater whilst the brass backnut is tightened. Tighten the brass backnut using the
key spanner supplied.
7. Fit the thermostat by sliding the stem into the upper pocket and carefully plugging the two male spade terminals on
the underside of the thermostat head into the corresponding female terminations on the element. Carefully push home
until the terminals are fully engaged.
8. Re-connect the electrical supply to the thermostat and earth post.
The Live (Brown) conductor should be connected directly to the thermostat terminal marked A.
The Neutral (Blue) conductor should be connected directly to the thermostat terminal marked B.
The earth conductor should be connected to the threaded post on the bracket marked
9. Re-fit the protective cover over the immersion heater assembly and secure using the nut previously removed.
10. Ensure the cylinder is correctly re-filled prior to switching on the immersion heater. Do not operate the immersion
heater with the protective cover removed.
Fig. 25
© Baxi Heating UK Ltd 2015
M5 THREADED SHAKEPROOF PLAIN
PILLAR WASHER WASHER
.
CUP EARTH M5 NUT
EARTH
WASHER WARNING LABEL
LABEL
EARTH BRACKET
SPOT WELDED
TO IMERSION
HEATER BOSS
43