How do you calculate subcooling?
If we measure the temperature on the liquid line exiting the condenser coil then we know the end temperature after the refrigerant has lowered in temperature. Subtract the lower temperature measured on the liquid line from the saturated temperature and you have subcooling!
What should subcooling be for 410a?
Most heating and cooling systems should operate at a superheat of 10F at the evaporator and between 20F to 25F at the compressor. if your HVAC system has a thermostatic expansion valve (TXV), the subcooling should be between 10F and 18F.
What is a good number for subcooling?
Subcooling on systems that use a thermostatic expansion valve (TXV) should be approximately 10F to 18F. Higher subcooling indicates excess refrigerant backing up in the condenser. On TXV systems with high superheat, be sure to check the subcooling as refrigerant is added.
Is too much subcooling bad?
If the subcooling is too high, the system will be overcharged, reducing performance, efficiency, and ultimately damaging compressor valves and start components.
How do you get superheat in HVAC?
Measure the suction line temperature and suction pressure at the suction side service valve. Ensure the temperature probe is insulated from any external influences. Convert the gauge pressure to saturation temperature and subtract this temperature from the suction line temperature. This is the total superheat.
How do I fix high subcooling?
Add refrigerant to increase subcooling. Recover refrigerant to reduce subcooling. Note that if the subcooling and superheat are correct, and the suction pressure is low, the system probably has low air flow. Correct the airflow problem and check the charge again.
What does a dirty condenser do to subcooling?
With a dirty or blocked condenser, even the subcooled liquid temperature coming out of the condenser will be at a higher temperature. This means that the liquid temperature out of the condenser will be further from the evaporating temperature.
What is HVAC superheat?
Superheat occurs when that vapor is heated above its boiling point. Superheat is critical in HVAC because it ensures the liquid refrigerant is boiled off before it leaves the evaporator and heads to the compressor. Even small amounts of liquid can cause detrimental damage to the compressor in an HVAC system.
What are normal pressures for 410A?
A normally operating R-410A system with the same condensation temperature of 120 degrees and a 45 degree evaporator saturation temperature will have a high side pressure of 418 psig and a low side pressure of 130 psig.