The Pump Down function works great. It saves all the R410A back inside the unit.
So, the line-set can be disconnected for work on the system. (or moving it).
The gauge set would be where the vacuum pump connected.
In Pump-Down, closing the Narrow Tube Service Valve, (in cooling mode) allows the compressor
to pump all of the R410A into outdoor HX coil. Trapping it.
Now, I've started wondering about
completely removing R410A from the system.
The Idea:
The "Indoor Unit" HX would be replaced with a Gravity Trap.
It would consist of a 'T' connector installed in a short loop (that replaces the line-set).
The bottom of the 'T' would point downwards into a connected tank,
the feed lines would be configured in a 'V' shape, to enhance gravity flow.
(Lines and tank would start off in a vacuum of 200 microns).
The
Pump Out operation might start, by opening the narrow tube (liquid line) service valve.
This would pressurize the 'T' and the collection tank. And maybe draw in some of the R410A in it's liquid state.
That should depend on the volume of the collection tank.
If the tank was pre-chilled, that should enhance collection.
Opening both valves, and running the system in cooling mode, should pump
liquid R410A into the 'T', where some of it will drop down into the tank.
The collection tank should sitting on a scale. (To see if this hack works)!
Pressure in the 'T' could be increased by partly closing the Wide Service Tube Valve.
Which might drive more liquid into the 'T' and into the tank.
Gas from the Wide valve would enter the compressor and help drive the
liquid into the storage tank.
When the scale showed the total charge had been collected,
a valve on the output side of the 'T' could be closed to reduce the pressure in that side of the recovery T-loop.
At <14 PSI, the Wide valve would be closed. Followed by the Narrow valve, and power off.
If it worked, they should be only a very small amount of 'gas' still in the system.
Comments please.
Thanks,
Rich