Refrigerants play a crucial role in air conditioning and refrigeration systems, as they are the substances used to transfer heat from one area to another. Understanding the various types of pressures and boiling temperatures associated with different refrigerants is essential for ensuring the efficient and safe operation of HVAC systems. In this article, we’ll explore the Refrigerant Pressures and Boiling Points, standing, and discharge pressure—as well as the boiling temperatures of common refrigerants.
Types of Pressures in Refrigerants
1. Running Pressure
Running pressure refers to the pressure of the refrigerant when the system is operating. It is an indicator of how effectively the refrigerant is circulating and transferring heat within the system. Running pressure varies depending on the type of refrigerant used and the operating conditions of the system.
2. Standing Pressure
Standing pressure is the pressure of the refrigerant when the system is not running. It reflects the refrigerant’s pressure at rest and can help identify potential issues such as refrigerant leaks or overcharging.
3. Discharge Pressure
Discharge pressure is the pressure of the refrigerant as it exits the compressor. It is a critical parameter because it impacts the efficiency of the heat transfer process. High discharge pressures can indicate problems such as dirty condenser coils or inadequate airflow.
Boiling Temperature of Refrigerants
The boiling temperature of a refrigerant is the temperature at which it changes from a liquid to a gas (boils) at a given pressure. This property is crucial because it determines the refrigerant’s ability to absorb and release heat. Different refrigerants have varying boiling temperatures, making them suitable for different applications.
Common Refrigerants and Their Properties
Below is a table summarizing the running pressure, standing pressure, discharge pressure, and boiling temperature of various refrigerants:
| Refrigerant Name | Running Pressure (psi) | Standing Pressure (psi) | Discharge Pressure (psi) | Boiling Temperature (°C) |
|---|---|---|---|---|
| R-134a | 10-12 | 80-90 | 80-90 | -26 |
| R-22 | 60-65 | 150-160 | 150-160 | -40 |
| R410a | 230-240 | 120-130 | 120-130 | -51 |
| R600a | 50-60 | 1-5 | 1-5 | -11 |
| R32 | 240-250 | 120-125 | 120-125 | -52 |
| R404a | 180-190 | 80-90 | 80-90 | -46 |
| R407a | 170-180 | 70-80 | 70-80 | -45 |
| R417 | 130-140 | 60-65 | 60-65 | -50 |
| R143a | 70-80 | 5 | 5 | -70 |
| R12 | 80-90 | 10-15 | 10-15 | -20 |
Each refrigerant is suited to specific applications depending on its properties. For instance, R-134a is commonly used in automotive air conditioning, while R410a is prevalent in residential and commercial air conditioning systems due to its high efficiency and lower environmental impact.
Understanding these pressures and boiling temperatures helps HVAC technicians diagnose and troubleshoot system issues effectively, ensuring optimal performance and longevity of the equipment.
How to Measure Refrigerant Pressures in HVAC Systems
Measuring refrigerant pressures is crucial to ensure an HVAC system runs efficiently. Incorrect pressures can lead to poor cooling, higher energy bills, and potential damage to the system.
Steps to Measure Refrigerant Pressure:
- Turn Off the System – Before measuring, ensure the system is off to avoid pressure fluctuations.
- Attach the Gauges – Use a manifold gauge set to connect to the low-side (blue) and high-side (red) service ports on the AC unit.
- Turn the System On – Set the thermostat to cooling mode and let the system run for 10-15 minutes to stabilize.
- Read the Pressure Gauges – Compare the readings to the recommended pressure levels in the unit’s manual.
- Interpret the Results –
- Low Pressure can mean a refrigerant leak, dirty filters, or clogged coils.
- High Pressure may indicate overcharging, blocked airflow, or dirty condenser coils.
Solution: If pressures are off, contact Airchill AC Maintenance and Duct Cleaning for a professional check-up. They ensure refrigerant levels are correct and your ducts are clean for smooth airflow.
Refrigerant Pressure Drop: Causes and Solutions
A refrigerant pressure drop happens when the pressure falls below normal levels, reducing cooling efficiency.
Common Causes:
- Refrigerant Leaks – Small leaks in coils, pipes, or connectors cause pressure to drop over time.
- Dirty Air Filters – Restricted airflow forces the system to work harder, affecting pressure balance.
- Blocked Expansion Valve – A faulty valve restricts refrigerant flow, leading to low pressure.
- Clogged Evaporator or Condenser Coils – Dust and debris reduce heat exchange, affecting pressure.
Solutions:
✅ Fix Leaks – Professionals use leak detectors to find and seal refrigerant leaks.
✅ Clean Filters & Coils – Regular maintenance from Airchill AC Maintenance and Duct Cleaning ensures unrestricted airflow.
✅ Inspect Expansion Valve – A technician can clean or replace a faulty valve to restore proper flow.
Ignoring pressure drops can damage the compressor and increase energy costs. Routine maintenance helps keep your AC in top shape.
Impact of Temperature Changes on Refrigerant Boiling Points
The boiling point of a refrigerant is the temperature at which it changes from liquid to gas. This is essential for cooling because the refrigerant absorbs heat as it evaporates.
How Temperature Affects Boiling Points:
🔹 Higher Temperatures – Increase refrigerant pressure, potentially causing overheating or inefficiency.
🔹 Lower Temperatures – Decrease pressure, which can lead to freezing coils or poor cooling performance.
Signs of a Problem:
- AC not cooling efficiently
- Ice forming on evaporator coils
- High energy bills due to system strain
Solution:
- Keep outdoor units shaded to prevent overheating.
- Schedule regular maintenance with Airchill AC Maintenance and Duct Cleaning to ensure refrigerant levels and pressures are balanced.
- Ensure ducts are clean for proper airflow, preventing system strain.
