Consider replacing your heat pump if it's over 10-15 years old, experiencing frequent breakdowns, or its efficiency has significantly decreased. If repair costs are approaching half the price of a new unit, replacement becomes economical. Unusual noises, inconsistent heating or cooling, and rising energy bills are additional indicators. Upgrading to a more energy-efficient model or if your current unit uses R-22 refrigerant (phased out due to environmental concerns) are also reasons to consider replacement for improved performance and sustainability.