If you are decommissioning an HVAC unit or want to change the gas that is in it, then you are obliged to recover the refrigerant that is contained in the unit first. Only licensed HVAC technicians can recover gas from a compressor. It is against the regulations set by the EPA for anyone who does not have a Section 608 Type 1, 2 3 License or Universal License to work with (or even buy) HVAC refrigerants.
The reason for those regulations is because refrigerants can be harmful to the environment if they are not properly handled, and they can also be quite dangerous. Some of them are volatile, and some could be harmful if inhaled. If you have a problem with your HVAC unit then you should contact a local HVAC company to get assistance.
Recovering HVAC Gas
According to the folks at tdx20.org your Section 608 certified HVAC engineer will likely follow a process similar to the following to work with your unit:
– Firstly, they will determine what type of unit they are looking and what gas that it works with. Older units may rely on Freon/R22, which is being phased out because it is damaging to the environment. Some slightly newer units may use R410a. Car HVAC may use R12, or R134a, among other options.
– Next they will hook up gauges to the low pressure side and the high pressure side. The low pressure side is usually the side with the bigger tube while the high pressure side will have a smaller tube.
– To ensure that they are working with hoses that don’t have any air contaminating them, they will purge the hoses of air by holding the hose away from them and opening the low side for one second, then the high side for one second. After opening each side, it will then be closed.
– The yellow hose will be hooked up to the ‘IN’ side of the recovery machine. There are a few different styles of recovery machine but the operation of them is broadly the same. The second hose connects to the ‘OUT’ port of the unit.
– The recovery unit will need purged too. To do this, just release some gas from the ‘low’ side and let that flow for one second.
– There should be two ports on the recovery tank. One port will be blue and one will be red. They will match the low and high gauges in color (blue for low, red for high). Hook them up appropriately, then open both ports on the recovery unit, and both ports on the recovery tank.
– Turn on the recovery unit, and then watch the gauges. What you want to see is the gauges fall to zero psig. Once this happens, close the gauges and turn off the recovery machine.
The above is just one way of recovering gas from a HVAC system. There are other options that use other machines. If you have a smaller, domestic or car machine then the above system will work OK. If you have a bigger unit with very large volumes of gas or liquid refrigerant then you may want to use a push/pull system instead. This uses a recovery unit to pull vapor from the recovery cylinder, and produce a high pressure discharge that will push liquid out of the HVAC system, and then push it back into the recovery cylinder.
The push pull method is best used only for systems that contain in excess of 10 lbs of refrigerant. If your system is smaller, has a reversing valve, or is a heat pump then this method would not work. In addition, if there is an accumulator between the service ports, then the push pull method could harm the machine. The push-pull method needs extra equipment, but it is worth doing for bigger units.
Let a Professional Do the Job
In general it is a good idea to leave these jobs to the professionals. Recovering refrigerant is a skilled job and there are a lot of things that can go wrong. If the job fails then you will be leaking refrigerant into the atmosphere. This could be an expensive and wasteful mistake that damages the environment, and it is also illegal to attempt the job if you are not properly trained. If a large amount of gas floods a residential property, then it could harm or even kill the people inside. Many of the gases are odorless, so accidental asphyxiation is a possibility.
HVAC technicians have extensive training in how to safely work with refrigerants, ensuring that people are not hurt and that the air conditioning units are properly repaired. They can reclaim gas to top up units, or just to dispose of them properly. They can do the job more quickly and efficiently than an untrained person too.
If you have a unit that relies on R-22 then it is particularly important that you leave the job to the professionals. As of January 2020, it will be illegal to make or import R22 and the only R22 that can be used is gas that was stockpiled by HVAC companies or that is recovered from machines. If your unit is leaking, then the leak must be repaired before you get it topped up. If you have your unit decommissioned then it is important that the gas is reclaimed and disposed of properly.
Again, these are all jobs that a properly trained HVAC technician can help you with. It makes more sense to have your unit repaired and serviced on a regular basis, than to leave it and be faced with an expensive repair bill at a later date. If you want to have your unit retrofitted to work with other gases, then that might require some changes to the compressor so that alternative refrigerants will work with that. Consult an HVAC specialist in your area for advice about the best drop-in replacements to use, and which ones would suit the environment that your HVAC system is designed to service.