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Step 4 – Verify the power supply
Check the power supply using an appropriate scale for 240 VAC.
1.
Measure the incoming voltage:
― WH17 / AE-115 have two readings (Fig. 4)
― WH27 / WH36 / AE-125 have three readings (Fig. 5)
2.
Check the pairing of the incoming power connections by
measuring the voltage of all combinations of L1 to L1 and
L2 to L2. Voltage between any of these pairs (L1-L1 or L2-
L2), indicates an installation error and must be resolved by
an electrician.
To Supply 1
To Supply 1
2 independent 40 amp double-pole
2 independent 40 amp double-pole
circuit breakers
circuit breakers
Data subject to change without notice | Printed in the USA | BTC 722002309 B | 05.2014
WH17, WH27, WH36 AE115, AE125, (FD108 and higher) | 3 |
Figure 3
Flow
Flow
Transducer
Transducer
Figure 4
17kW terminal block
17kW terminal block
S S upply 1
Supply 1
S S upply 2
Supply 2
T T o Supply 2
To Supply 2
T T o Supply 1
To Supply 1
To Supply 2
T T o Supply 2
To Supply 3
To To Supply 3
27kW - 3 independent 40 amp double-pole circuit breakers
27kW - 3 independent 40 amp double-pole circuit breakers
36kW - 3 independent 60 amp double-pole circuit breakers
36kW - 3 independent 60 amp double-pole circuit breakers
3.
Check that voltage is reaching the PCB by measuring the
voltage between the blue and brown power connections
on the board itself (Fig. 6).
PCB power connections
(brown / blue wires)
4.
Shut off the circuit breakers powering the appliance, lock
them, and verify that there is no voltage at the unit.
5.
Document your fi ndings in the Water Heater questionnaire.
Figure 5
27/36kW terminal block
27/36kW terminal block
Supply 1
Supply 1
S S upply 2
Supply 2
Supply 3
Supply 3
Figure 6
Heater bottom
Bosch Thermotechnology Corp.
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