Split System Retrofit After a Compressor Burnout
You attend a 12 kW R-410A split system in a small office. The compressor has failed with a winding burnout; the service record shows the system had a slow leak for two seasons and was topped up twice without a leak being located. The customer wants the refrigerant recovered, the burnt-out compressor replaced and the system put back into service quickly. You have a recovery cylinder rated for R-410A, a two-stage vacuum pump, and a nitrogen regulator. The pipe run is 18 m with one brazed joint in the ceiling void that is difficult to access. Ambient is 28 °C. The customer asks whether you can just 'gas it up and go' once the new compressor is fitted.
1. Outline how you recover the refrigerant and prepare the circuit before the new compressor is installed, and explain why the leak history changes your approach.
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Recover the charge into a dedicated R-410A cylinder using recovery equipment, not by venting. Weigh the recovered amount and record it. Because there has been a chronic leak, the circuit will contain acid and moisture from the burnout; that contamination must be removed before a new compressor is fitted, or the new compressor will fail.
Steps:
- Recover refrigerant and record the quantity.
- Remove the failed compressor and fit new filter driers (and a suction-line filter if the burnout was severe).
- Purge/flow nitrogen while brazing to prevent internal oxidation.
- Pressure-test with OFN to locate the leak - the accessible brazed joint and any flare/braze points are prime suspects. Repair the leak, then re-test.
- Evacuate to a deep vacuum (typically below 500 microns, held and decay-tested) and confirm no moisture remains.
- Recharge by weight to the manufacturer's figure, adjusting for the pipe run.
The leak history is the key: the system has been losing refrigerant for two seasons, so the leak must be found and repaired as a legal and technical requirement, not just topped up. Recharging without repair would breach the leak-checking/repair obligations and repeat the failure.
2. The customer says topping up is cheaper than finding the leak. Explain the regulatory position and what you must record.
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Under the F-Gas regime, operators of equipment above the relevant CO2-equivalent threshold must have leaks checked at prescribed intervals, and any leak detected must be repaired without undue delay, followed by a verification check. Simply topping up a known leaking system is not acceptable.
For a 12 kW R-410A system, the charge is typically several kg; R-410A has a high GWP (around 2088), so even a modest charge can exceed the threshold that triggers mandatory leak checks. I would calculate the CO2 equivalent (charge in kg × GWP) to confirm the applicable check frequency and record it.
Records to keep: the CO2-equivalent charge and GWP, the leak check date and result, the repair carried out and the follow-up verification, quantities recovered, and refrigerant added. I would explain to the customer that a compliant repair is not optional and that repeated top-ups without repair are both a legal exposure and a false economy.