Baxi Combi 133 HE Plus Installation & Servicing Instructions Manual page 28

PCB
Fig. 30
PCB
Fig. 30a
PCB
Fig. 31
28
© Baxi Heating UK Limited 2005
Electrical
Cover
Link Wire
1 2
External Room
Timer Thermostat
Frost
Thermostat
8.0 Installation
8.9 Fitting a Room Thermostat
1. To fit a 2-wire thermostat, remove link and wire the
thermostat switch between positions 1 & 2 (Figs. 30a).
A cable clamp is provided for incoming cables.
8.10 Fitting a Frost Thermostat
1. The frost thermostat is connected between positions
1 and 2 (Fig. 31) or between mains isolator and position
2. Secure the incoming cable/s with the cable clamp and
replace the cover.
8.11 Electrical System Checks
1. Earth Continuity Check: Isolate the appliance at mains
supply. Using a multimeter set to ohm's scale, test
between any appliance earth point and the earth pin on
the socket. The resistance should be less than 1ohm. If
the resistance is greater than 1 then check all earth wires
for continuity and ensure that all connections are clean
and tight.
WARNING: If the resistance is still greater
than 1ohm the fault still exists and it could be
dangerous to work with the appliance live.
2. Short Circuit Check: Isolate the control system, set all
switches and thermostats to calling for heat. Set the
meter on ohm's scale. Test from L to N on control
system terminal block - if the resistance reads zero there
is a short circuit.
3. Resistance to Earth Check: Isolate the control system,
set all switches and thermostats to calling for heat. Set
the meter on ohm's scale. Test between L and E - the
resistance should be greater than 1 mega ohm.
4. Polarity Check: If all the tests you have carried out so
far are OK, then reconnect the system to the mains
supply. Set the meter on Volts AC scale (starting at the
highest voltage).Test at terminals:
L and N - meter should read approx 240 Vac
L and E - meter should read approx 240 Vac
N and E - meter should read from 0 to 15 Vac
5. Fuse Check: Remove the fuse, check fuse on ohm's
scale there should be no resistance (infinity) or maximum
reading. If no reading is obtained change the fuse. Check
fuse is 3A.