Benchmark Alpha CD18S Installation And Servicing Instructions page 18

3. If an external control, i.e. room thermostat or external clock is to be fitted, remove the terminal block cover and
remove the link between terminals 1 and 2. Pass the cable through the cable clamp and connect it to terminals 1 and 2.
Replace the terminal block cover. (Refer to Section 2.9).
Note: If an internal clock is being fitted, refer to Section 2.9, Fig. 1 for connecting to terminals 3 and 4.
4. Replace the terminal block, ensuring it is located correctly on the plastic pins and replace the cover.
5. Ensure that there is sufficient free cable to allow the control panel to be raised and lowered then tighten the cable clamp screws.
6. Leave the control panel open until commissioning procedures have been completed.
7. Carry out electrical system checks - Short circuit, Polarity, Earth continuity and Resistance to earth with a suitable multimeter.
4.9 FITTING AN INTERNAL CLOCK KIT (Optional) - Fig. 21
Ensure the electrical supply to the boiler is isolated.
IMPORTANT - Only use an Alpha two channel clock. Do not fit a single channel clock.
1. Remove the two screws securing the clock cover at the rear of the control panel.
2. Remove and discard the clock blanking panel.
3. Insert the clock into the opening and secure in place with the screws supplied - do not overtighten the screws.
4. i). Disconnect the clock wiring from the in-line connector and connect the wires to the clock as follows:-
Brown wire to terminal 1, Blue wire to terminal 2, Black wire to terminal 3, Grey wire to terminal 4 and White wire to
terminal 5, (or, as per the instructions supplied with the clock). Ensure wiring is correct.
ii). Replace the clock cover. Do not overtighten the fixing screws.
iii). Leave the control panel open until commissioning procedures have been completed.
Fig. 21
Alpha CD18S/24S/30S - Installation 17