What’s the Problem with an Improper Installation of an R-410a System?
“The most important day in the life of a system is the day it is installed.”
This statement has never been more important. Since the industry has called for the dismissal of r-22 refrigerant systems as of January 1, 2010, consumers have never been more vulnerable. The new systems that are being installed today are using the new environmentally safe refrigerant called r-410a. From an environmental standpoint this is a very intelligent move because r-22 is not environmentally safe.
So What’s The Problem?
A heating and air conditioning system is the most expensive appliance to operate in the home. In fact 45-55% of your utility bill goes to keeping you warm in the winter and cool in the summer. In some cases a system can cost 3-5 times more to operate over the life of the system than the purchase price.
Engineers are constantly looking for new ways to reduce our Nation’s energy usage by improving the efficiency of the heating and air conditioning systems. The problem is not with how a heating and air conditioning systems design but the way it is matched up and installed in the field.
GE hung on to a marginally profitable central air-conditioning business for twenty years because people thought it was necessary in order to have a full-line major appliance company. In reality, headquarters hated air-conditioning because its success was so dependant on the installers. These independent contractors would put our machines into homes and then drive off, and GE lost control of the brand.
- Jack Welch
The advantage of the R-22 system was connected to its forgiveness of how it was setup in an air conditioning system. In fact in quite a few cases we are seeing R-22 systems last as much as 25-30 years before the need to be replaced.
On the other hand, the new R-410a system is very sensitive and requires a precision installation in order to avoid greatly affecting the life of the system. Trace amounts of moisture could destroy the system in as little as 1-5 years. Because of the sensitivity and liability of these new R-410a systems, more than 80% of the mechanical contracting industry stayed away from these systems until they were forced to make the change to installing them on January 1, 2010. There is simply no way to determine today if a company and all of their field personnel know how a R-410a heating and air conditioning system is being installed. In 2010 we have interviewed approximately 50 installers for employment. We have yet to receive a correct answer as to how these systems are to be installed.
The correct answer to how an R-410a refrigeration system works is as follows:
- Based on engineered specifications make sure the refrigerant piping is the appropriate size. A reduction in the suction-line diameter will result in capacity loss, because the mass flow rate of refrigerant to the compressor is decreased.
- Refrigerant lines should be supported to prevent sagging in the pipe that can interfere with oil return back to the compressor.
- Uncoil the refrigerant tubing while taking care not to kink or dent it.
- Remove the pressure tap port valve cores before brazing the refrigerant tubing to the service access valves. Failure to do so will ruin the valve cores.
- This is one of the most crucial steps in the installation process and is also the main step that is omitted in the installation process.
Connecting Refrigerant Tubing – Dry nitrogen must be purged through the tubing during brazing to keep oxides from forming. Flakes formed during brazing without a nitrogen purge will separate from the tubing wall to circulate with the refrigerant and oil, eventually forming restrictions.
Set the regulator for a low pressure – typically, 1 to 2 psi is recommended for this process. Flow the dry nitrogen into either valve pressure tap port, through the tubing and indoor coil, and out the other port while brazing. Nitrogen causes no damage to the environment.
- After brazing, quench the joints with water or a wet cloth to prevent overheating of the service valve.
- Check for Leaks – Use dry nitrogen to pressurize the tubing and indoor coil through the service valve ports located at the condenser. Check for leaks by using an approved bubble solution or other leak-checking method. Continue the process until the system has been determined to be leak free.
- Connect the vapor-line and liquid-line pressure taps to a vacuum pump and micron meter.
- This step is also almost always omitted. Evacuate the refrigerant lines and indoor coil to at least 350 microns. Close off the valve to the vacuum pump and observe the micron meter. If the pressure does not rise above 500 microns in one minute, the evacuation process is complete and the vapor-line and suction-line service valves may be opened.
- Charge The System – Proper refrigerant charge can be verified using the superheat or subcooling charging method. HVAC Q1 Specification 4.2.1 requires refrigerant charging to be within specific tolerances. Subcooling is a test done at the condenser outlet on system equipment with a thermostatic expansion valve (TXV). Superheat is a test done on systems equipped with fixed orifice, piston-type metering device, and cap tube systems using measurements taken at the suction line (at condenser). Subcooling and Superheat measurement results are then compared to equipment manufacturer’s data to evaluate the refrigerant charge.
Subcooling Test Evaluation – The subcooling test measurement should be within 3ºF of the equipment manufacturers specified optimal subcooling.
Superheat Test Evaluation – The superheat test measurement should be within 5ºF of the equipment manufacturer’s required superheat value.