Manual Heat Pump Model HHPM-V.2- SEP 2012
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7.7. Leak test
After the system has returned to ambient temperature proceed with leak testing. Attach a set of
standard refrigeration gauges to the suction and discharge access valves. Pressurize the system with 27
bar of pure nitrogen gas via the "common" gauge port (gauge valves open). Isolate the Nitrogen supply and
note the pressure reading. Allow the system to remain in this condition while performing a leak check with a
soapy water solution.
Apply the soapy water solution to all connections that were previously worked on as well as the
hose/gauge connections. Bubbles will form in the soapy water solution wherever a leak is located.
If leaks are found then the nitrogen must be bled off and the gauges removed for additional
brazing. Be sure to check any solder connections that may have been loosened during the initial brazing
operation.
If no leaks are found utilizing the soapy water solution then allow the system to remained charged
with nitrogen for a minimum total of 3 hours (preferably overnight). At the end of this time period, check the
pressure reading of the gauges. They should be unchanged from the previous leadings (except for
changes due to a change in ambient temperature).
7.8. Evacuation
Prepare an evacuation pump for evacuation of the system by ensuring that there is fresh
refrigeration oil in it and that the connections are in good working order. There should also be a vacuum
gauge inline with the system. This gauge should be able to be isolated from the evacuation pump to
determine the system vacuum level.
Connect the evacuation pump to the "common" gauge connection and energize. Allow the
evacuation pump to run for several hours.
Check the vacuum gauge reading. If the reading is less than 500 microns, isolate the evacuation
pump from the system. Allow the reading to stabilize. If the vacuum maintains a reading below 500 microns
for 10 minutes, close the gauges isolation valves. Shutdown the evacuation pump, then proceed to
charging.
If the reading goes above 500 microns, continue to pump down. If the vacuum reading cannot be
maintained below 500 microns after pumping down overnight then the system will need to be checked for
leaks again
