On install day a pressure test is the engineer proving the new pipework holds before refrigerant is let into the system. You may see gauges and a wait. You are not asked to carry it out, read a target, or buy the gas they test with. If it fails, they find the leak before the system is charged. Ask for a pass to be written on the commissioning record. This page does not give a test method, a pressure, or a procedure.
Gauges and a wait before the charge
The pipes and joints are new or newly connected. The test is there to show those joints hold. A system that is opened and charged with no test is missing a step you can ask about on the day. It happens before the refrigerant is released into the new pipework. You may see gauges and a wait. A failure means they fix the joint before charging. The gauges are the engineer's instruments. A steady reading that they accept, and time spent rather than a glance, is what a customer can reasonably expect to see. The number itself belongs in their training and the manual, not on a householder's checklist of targets. No DIY version of this test exists on this page.
The person doing this is an F-gas certified company, because the circuit they are about to commission contains refrigerant. Energy Saving Trust describes the finished machine as an air-to-air heat pump. The test is how the pipework earns that description.
A pass written beside the model numbers
A pressure test is not the vacuum pull. One checks that the pipework holds pressure. The other removes air and moisture before the charge. Both are normal on a proper install. Seeing one does not mean the other happened. Ask for the commissioning record to say the test was done and that it passed. Keep it with the model numbers. A later engineer, or a warranty desk, would rather see that note than a verbal memory. Reused copper, if it is being used at all, needs this test as one of the conditions, beside the right diameter and a clean line. A pretty trunking job is not a substitute.
Frequently asked questions
Should I see a pressure test on install day?
Yes. It is a normal, customer-visible step before the system is charged. Ask the engineer to confirm it passed and to note that on the record.
Can you tell me the pressure to test to?
No. This page will not give a DIY procedure or a test pressure. The engineer follows the manual and their certification.
Is the pressure test the same as the vacuum?
No. The pressure test checks that the pipework holds. The vacuum pull removes air and moisture. A proper install includes both.
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How this guide was prepared
This guide was written by the Local AC Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.