Potterton Combi 80, Installation & Service Instructions Manual

Page: 32 / 47

Replacement of Parts - Page 32
5.19 Water Flow Switch (D.H.W.)
1. Remove the white front case and base panel.
See 4.1 & 4.2in ’Routine Maintenance’.
2. Lower the control panel assembly by undoing the
securing screw at the top right hand side of the control
panel.
3. Close the 15mm cold water isolating valve, open the
lowest hot water tap then remove the drain screw from
the isolating valve to drain the system.
4. Note the position of the electrical connections and
remove the two wires from the micro switch.
5. Undo the two nuts holding the flow switch in place and
remove the pressure switch.
6. Transfer the micro switch assembly by loosening the
locknut and unscrew the switch, refit the micro switch to
the new flow switch and position the switch as
dimensioned in Fig. 21.
7. Re-assemble in reverse order. Ensure the wires are
connected correctly as shown in Fig. 21.
5.20 Microswitch (D.H.W FLOW SWITCH)
1. Remove the white front case and base panel.
See 4.1 & 4.2 in ’Routine Maintenance’.
2. Lower the control panel assembly by undoing the
securing screw at the top right hand of the control panel.
3. Note the position of the electrical connections and
remove the two wires from the micro switch.
4. Loosen the locknut and remove the switch, fit the new
micro switch (with locknut) to the flow switch and
position the switch as dimensioned in Fig. 21.
5. Re-assemble in reverse order. Ensure the wires are
connected correctly as shown in Fig. 21.
5.21 Pump
- Fig. 16
For ease of replacement it is advisable to fit a new motor
(head) assembly to the existing pump housing. This will
prevent excess dismantling and save time as the motor
assembly may well need to be removed from the new pump
to correctly position the electrical control box.
1. Remove the white front case and base panel.
See 4.1 & 4.2in ’Routine Maintenance’.
2. Lower the control panel assembly by undoing the
securing screw at the top right hand side of the control
panel.
3. Unplug the pump wiring at the in-line connector.
4. Drain the central heating circuit as described on Page
26.
5. Remove the motor head assembly from the pump body
by removing the four retaining screws.
6. Transfer the wiring harness from the old pump to the
new, note the following wiring terminations.
Live (L) Pink
Neutral (N) White
Earth Green/Yellow
7. Fit the new pump head assembly using the new sealing
ring, ensure that the pump terminal block is to the right
hand side with the wires running out of the top. Secure
tightly and re-assemble in reverse order.
Re-charge the system as described in Section 1.8 and
check for leaks. When applicable, ensure that the pump
is set to the highest speed.
The Microswitch Position Should Be Limited To The Shaded Area. (When Adjusting To Obtain The 5.5mm Gap).
NOTE: “The Dimension of 5.5mm will give an approximate initial setting. The final setting is made by checking the water flow
rate at which the switch turns OFF, when the boiler is hot. Run the D.H.W. with the boiler in ‘Summer’ mode, until
the water is hot. Gradually decrease the water flow rate until the flow switch turns OFF. The water flow rate, just
before the switch turns OFF, should be between 3 & 3½ litres, this will take between 9 and 11 seconds to fill a pint
bottle. If the switch turn OFF at an incorrect rate, adjust the position of the microswitch. It may be necessary to
move the microswitch by a complete turn, but always keep it in the shaded area”.