Charging a refrigeration system is one of the most challenging tasks a service technician will face. A bad charge will make your AC work harder and will increase your electricity bill by 20 to 40 percent. Charging your AC unit at the recommended levels at installation can increase its lifespan by up to 5 years. Excessive refrigerant inside an air conditioner can damage the compressor by collecting inside of it, which will lead to subcooling, or temperatures below normal. The extra refrigerant can also flood the compressor and damage its mechanical components. An overcharged air conditioner will also create higher pressure inside the system causing the system to be more expensive to run since it will not cool as effectively.
Conversely, your AC evaporator coil will send the refrigerant through a line and if the refrigerant is low, the coils get too cold and cause a cold liquid refrigerant to flow through the line. Then the surrounding moisture in the refrigerant line will freeze up. A frozen coil will further lose heat absorption ability, causing more ice to grow until the air conditioner cannot work at all. Low refrigerant flow will cause a loss of capacity and efficiency in a cooling system. Loss of refrigerant will also threaten to damage the compressor, leading to it overheating.
Without proper charging, you are risking paying thousands of dollars in repairs/maintenance costs. Repairing an air conditioner condenser costs an average of $150 to $1,000 or more. Replacing the entire coil runs $900 to $2,800. Labor alone makes up about half the fees. HVAC technicians charge anywhere from $50 to $150 per hour. Fixing damage to the compressor is one of the most expensive air conditioner repair jobs and may require the whole system be replaced, and installing a new air conditioner can cost anywhere between $3,350 and $5,912 per unit.
Title 24 requires that, if air conditioners are altered by the installation or replacement of refrigerant-containing system components (such as the compressor, condensing coil, evaporator coil, refrigerant metering device, liquid line filter drier or refrigerant line-set), these components shall have the proper refrigerant charge field verified in accordance with all applicable procedures specified in the Residential Appendices RA3.2. As a result, refrigerant charge verification is a common process that may need to be performed by a HERS Rater for Title 24 compliance.
As a building owner, you should expect your building features to be installed as designed and compliant with the Energy Code. Field verifications and diagnostic testing are performed by special third-party inspectors called Home Energy Rating System (HERS) Raters. The California Energy Commission (CEC) has given this responsibility to the HERS Raters, who must be specially trained and certified to perform these services to address poor construction quality and equipment installation. As a contractor or developer, it is important to verify that the installed building features are meeting the energy performance expected by the Energy Code. A HERS Rater is required when the Certificate of Compliance documents indicates HERS measures are required.
One of the many tests that are done by the HERS Rater in the field is the “Refrigerant Charge Test”. This test is designed to verify that the HVAC system was properly charged and helps identify potential refrigeration system faults. After the installing contractor has finished installing and charging the system, the HERS Rater then performs the test with approved refrigerant gauges by the California Energy Commission. While performing the test, HERS Raters check two important readings: the superheat and the subcooling levels. While superheat indicates how much refrigerant is in the evaporator (high superheat indicates not enough, low superheat indicates too much), subcooling gives an indication of how much refrigerant is in the condenser. The HERS Rater then verifies with approved refrigerant gauges that the subcooling levels and superheat levels are where the manufacturer intended for that specific system. Having your AC unit verified by a HERS Rater is very important in preventing unnecessary future cost to your buildings.
For more information on title 24 HERS Compliance and good building practices, please don’t hesitate to contact VCA Green below.
Contributing Writer: Samuel Vallejo, HERS Rater
Moe Fakih, Principal