Quote Originally Posted by nevgee View Post
Lets get back to basics. ..... no theoretical wizardry no sadle sore razzamataz
The system is an isolated pipework installation. There are no other components or valved arrangements ... it is only a pipe work circuit with all condensers, condensing units, compressors, evaporators isolated and valved off.
The pipework is insulted, is isolated from all other components, has been purged, pressure tested and assumed to be leak tight and clean.
Then a vacuum pump is applied and after a period over night vacuuming down to 0.7 torr, a rise test after 2 hrs shows no rise in pressure. The system is set into operaton then after two days of running an lp trip occurs?
These were Toshiba 3-Pipe heat recovery systems. The outdoor unit isolation valves are not opened until the the strength pressure test, the leak pressure drop test and the moisture indicating vacuum rise test are all complete.

The unit was put into operation on a Friday. They called me on the Monday.