Si39-303 Appendix
General Information 147
7.12.4 Example 4: Pressure down despite absence of leaks during air tight
test (all model)
Situation
In order to carry out local air tight tests on the refrigerant piping the system was pressurized via the liquid
pipe service port and after 24 hours the pressure was found to have fallen. The local refrigerant piping
alone does not lose any pressure. Maybe the gas leak is supposed to be located in the indoor unit itself.
Source of
Problem and
Remedial Action
The system was pressurized from the liquid pipe side and the gas pipes were therefore not pressurized.
The system was then left under pressure for 24 hours but during that time gas leaked through into the gas
pipes due to internal leaks within electronic expansion valves and the gas pressure inside the liquid pipes
consequently dropped.
Main Points
When carrying out air tight tests on local pipework
it is essential that the system be pressurized via
both the liquid pipes and the gas pipes
.
Heat exchanger
Fan
Electronic
expansion valve
Filter
Filter
Indoor unit
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