Buderus Logamax plus GB162-80 kW Service Instructions Manual page 32

6 Diagnosis
section 32
For devices with a hot-water supply: no or insufficient DHW; radiators, convectors, etc. may be heated without a
heat demand.
Step 1  Put the main power switch on the BC10 in position "0" (Off) as referred to in section 70 and put the main power
switch in position "1" (on) as indicated in section 80.
Step 2  Open a hot-water tap.
Step 3  Check to ensure that the hot-water primary supply pipe to the tank warms up.
Step 4 Does this pipe warm up (to approx. 140 °F (60 °C))?
Step 5 Diagnosis: The cause of this fault does not lie with the heating boiler, but with the water supply or hot water
tank.
Step 6  Check to see if the cold-water inlet and hot-water outlet have been incorrectly connected to the storage-type
water heater.
Step 7 Are the pipes connected correctly?
Step 8 Diagnosis: The pipes have been connected incorrectly. Action: Connect the pipes correctly.
Step 9  Close the stop tap in the cold-water inlet and open a hot-water tap at random to see if water is still flowing.
Step 10 Is this the case?
Step 11 Diagnosis: The cause is a defective (thermostat-controlled) mixer tap, a thermostat-controlled mixer valve
or a short circuit between the hot- and cold-water pipe circuits.
Action: Replace the relevant component or connect the pipes correctly.
Step 12  Check to see if any other external part of the drinking-water system is a possible cause.
Step 13 Is such a cause detected?
Step 14 Diagnosis: Another external part of the drinking-water system is a possible cause of the fault.
Action: Take the affected components out of service.
Step 15  Check
– the DHW mode
– that the DHW temperature is adjusted to a high enough setting according to section 81;
– that the DHW supply has not been shut off by the timer-switch program of the RC regulator.
Consult the operating instructions of the RC regulator.
Step 16 Are the settings okay?
Step 17 Diagnosis: The settings are not OK. Action: Adjust the settings.
Step 18  Open the stop tap of the cold water inlet pipe and a hot-water tap.
Step 19  Check that the LED "DHW demand" on the BC10 is lit, see section 14, [11].
Step 20 Is the LED lit?
Step 21  Check the DHW temperature sensor, see section 93.
Step 22 Is the DHW temperature sensor okay?
Step 23 Diagnosis: The DHW temperature sensor is defective.
Action: Replace the DHW temperature sensor, see section 96.
Step 24  Check the DHW temperature sensor lead as indicated in section 94.
Step 25 Is the wire okay?
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as indicated in section 23;
Logamax plus GB162-80 kW/100 kW - Subject to modifications resulting from technical improvements!
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Yes: Step 5
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Section 67
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Section 67
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Section 67
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Section 67
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