Protection Functions - Bosch 15 SEER2 Series Installation Instructions Manual

Installation Instructions

13.6 Protection Functions


Outdoor coil temperature protection (T3)
i. If T3 > 142°F, compressor is de-energized.
ii. If T3 < 129°F, compressor is energized.

Ambient temperature protection (T4)
i. If 40°F ≤ T4 < 125°F, unit can operate in cooling.
ii. If 5°F ≤ T4 < 86°F, unit can operate in heating.
iii. If T4 < 6.8°F, heat pump will provide 24V control to indoor unit
energizing electric heat (if installed).
See Product Specifi cation for extended performance data.

Discharge Temperature (DT) protection (T5)
i. If DT > 230°F during cooling mode, the compressor will stop.
ii. If DT < 185°F during cooling mode, the compressor will restart.
iii. If DT > 230°F during heating mode, the compressor will stop.
iv. If DT < 185°F during heating mode, the compressor will restart.

High Pressure (HP) protection (mechanical open/close
pressure switch)
i. High Pressure Switch opens at P > 580 PSIG, the compressor
and outdoor fan stop.
ii. High Pressure Switch closes at P < 435 PSIG, the compressor
and outdoor fan restart.

Low Pressure (LP) protection
i. If Low Pressure < 43.5 PSI for 5 minutes during cooling mode,
the compressor and outdoor fan will stop.The system will
attempt to run again after 3 minutes.
ii. If condensing temp. Tc < outdoor ambient temp. T4 during
heating mode, the compressor and outdoor fan will stop.

Module (inverter) protection (TF)
i. If TF > 165°F, the compressor and outdoor fan will stop.
ii. If TF < 140°F, the compressor and outdoor fan will restart.
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Bosch 15 SEER2 Inverter Ducted Packaged Heat Pump - BTC 761701319 A (12.2022)