Boulter Buderus Benchmark 600-28C Installation And Servicing Instruction page 54

5 Servicing
Check each sensor's cable by measuring its resistance
(see fig. 81, fig. 82, fig. 83 and fig. 83).
Subject to modifications resulting from technical improvements!
54 Installation and maintenance instructions for wall-mounted condensing gas boiler 600 - 28C • 01/2004
fig. 80 Measure resistance of hot water heat retaining sensor
fig. 81 Measure resistance of bi-sensor
fig. 82 Measure resistance of return sensor
Boulter Buderus Ltd. • http://www.boulter-boilers.com