2 Stage Heat Pump Defrost Options Defrost options

2 -Stage Heat Pump Defrost Options • Defrost options: – 30, 60, 90, 120 or Auto (Infinity/Evolution only) • Defrost initiate temp: 32° F • Defrost terminate temp: 65° F – Lower defrost noise • Normal defrost only occurs below 50° F outdoor temperature

Ideal/Perfect Defrost Infinity/Evolution Set as Default in UI DEFROST TIME NEXT DEFROST INTERVAL < 3 minutes 120 minutes 3 to 5 minutes 90 minutes 5 to 7 minutes 60 minutes > 7 minutes 30 minutes

2 - Stage Heat Pump Forced Defrost • Forced defrost pins provided on board • Command also available at User Interface • Short pins for 5 sec and release or UI command • If coil temp is below initiate and outdoor temp is below 50 – full defrost cycle • If coil temp is above initiate temp OR outdoor temp is above 50 – 30 second defrost cycle occurs

Time Delays • One minute off between stages – Bristol only • 5 minute mandatory high Stage on power up or 12 hours of standby – Bristol only • Auxiliary heat remains energized for 15 seconds after defrost completion

Time Delays • 20 second outdoor fan delay after defrost – Reduces fog effect • 1 minute delay in cooling mode before turning outdoor fan off if outdoor temp is 100 deg F or higher – For easier starting

Time Delays • 2 minute to return to standby from last valid communication • 5 -minute time guard between compressor cycles – Can be defeated by shorting forced defrost pins for 1 second and releasing – Can also be sped up by pressing fan and temp up together

Outdoor Thermistors Verification • Considered open if resistance is reads 500 K Ohms or higher (-50ºF or below) • Considered shorted if resistance reads 1 K ohms Or lower (188ºF or higher) • Coil and Outdoor temp thermistors are compared to verify proper range • If thermistors are failed, system reverts to default operation

Outdoor Thermistors Comparison • Begins 20 min after defrost termination • Ignored during low ambient cooling • Ignored until unit as run for 5 consecutive minutes

Outdoor Thermistors Comparison Range Error – Heating Might Change • If the outdoor thermistor indicates 30 F warmer than the coil thermistor OR • If the outdoor thermistor indicates 10 F cooler than the coil thermistor

Outdoor Thermistors Comparison Range Error – Cooling MIGHT CHANGE • If the outdoor thermistor indicates 10 F warmer than the coil thermistor OR • If the outdoor thermistor indicates 20 F cooler than the coil thermistor`

Thermistor Failure Default Operation