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Bosch Compress Hb fault code

Bosch Compress heat pumps

What the Bosch Compress Hb fault code means, from the manufacturer's own service literature, and the UK models it applies to.

What it means

PP protection trips 3 times and Tw_out < 7 °C

PP protection trips 3 times and Tw_out < 7 °C

Source: Bosch Compress 2000 AWF Installation Manual 6721859133, §12.2 (pp.156-159, render-verified)

UK models this code applies to

Tap yours to open Hb on that machine.

Outdoor units37
Compress 6000 AW-5Compress 6000 AW-7Compress 6000 AW-9Compress 6000 AW-13tCompress 6000 AW-17tCS3400iAWS 4 OR-SCS3400iAWS 6 OR-SCS3400iAWS 8 OR-SCS3400iAWS 10 OR-SCS5800i AW 4 OR-SCS5800i AW 5 OR-SCS5800i AW 7 OR-SCS7000i AW 5 OR-SCS7000i AW 7 OR-SCS7000i AW 9 OR-SCS7000i AW 13 OR-SCS7001iAW 5 OR-SCS7001iAW 7 OR-SCS7001iAW 9 OR-SCS7001iAW 13 OR-SCS7001iAW 17 OR-TODU 7.5sODU 10sODU 11sODU 11tODU 12sODU 12tODU Split 2ODU Split 4ODU Split 6ODU Split 8ODU Split 11sODU Split 11tODU Split 13sODU Split 13tODU Split 15sODU Split 15t

Hb on these comes from each model's own manual, which may not match the meaning above — tap yours to read it.

Outdoor units14
CS2000AWF 4 R-SCS2000AWF 6 R-SCS2000AWF 8 R-SCS2000AWF 10 R-SCS2000AWF 12 R-SCS2000AWF 12 R-TCS2000AWF 14 R-SCS2000AWF 14 R-TCS2000AWF 16 R-SCS2000AWF 16 R-TCS2000AWF 18 R-TCS2000AWF 22 R-TCS2000AWF 26 R-TCS2000AWF 30 R-T

Now the harder half: proving what caused it

Hb names a symptom, not a root cause. In the app, the same code opens a guided investigation: what to measure first, the expected values for your exact model, and an honest verdict — including “nothing in this machine is broken” when that's what the readings say.

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