HVACopediaBosch · Heat pump · Other
Operating limits and compressor protections
What happens, in order
- Outdoor coil (T3) at or above 147.2F (Light) / 150F (Premium Connected): compressor off; restarts when below 133F
- Cooling allowed from 40F up to 120F outdoor on Light (15F to 125F on Premium Connected)
- Heating allowed from 3F up to 86F on Light (-4F to 86F on Premium Connected); below 1.4F (Light) or -4F (Premium Connected) the outdoor unit calls the indoor electric heat
- Discharge temperature above 230F compressor stops; restarts below 185F
- High pressure switch opens above 580 psig: compressor and outdoor fan stop; they restart when it recloses below 435 psig
- Low pressure below about 22 psig for 3 s in cooling (Premium Connected also below 10.2 psig in heating): compressor and fan stop and the system tries again after 6 minutes
- Low discharge superheat below 9F for 40 minutes is also a protection
- Five P21 protections within 100 minutes lock the system out
Timings and thresholds
| Item | Value |
|---|---|
| Low-pressure retry delay | 6 min |
| Low-pressure detect time | 3 s |
| High pressure open / close | 580 / 435 psig |
| Discharge temperature stop / restart | 230F / 185F |
| Low superheat | Below 9F for 40 min |
Codes you may see during this
Applies to: Bosch IDS inverter heat pump condensing units
Models
More Bosch heat pump sequences
- Crankcase heater and reversing valve behaviour · Startup
- Demand defrost · Defrost
- Manual (forced) defrost test · Defrost
- Oil return and force (charge) mode · Other
Related
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Sequences of operation, error codes and tips work offline in the HVACopedia app.
Source: Bosch IDS Light (BOVA15, R-454B) installation BTC 762003308 D, 17 System operation (17.7); Bosch IDS Premium Connected (BOVA36-60-20) installation BTC 762003301 D, 18 System operation (18.7); fault table in the same sections. Written in our own words; timings can differ by model and software version, so check the manual for your exact unit.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.