I use one very much like this https://www.amazon.com/Happybuy-Prop...NsaWNrPXRydWU=
Just drain the unit when you leave. I drain mine by just shutting off the inlet source (a line from my permeate tank), open a drain valve for the cold water, and open the hot water valve, it drains completely. It give me all of the water I need, at up to just over 3 gpm and at 110 F with 35F water in. Fires on propane.
When cleaning the RO, if I need to raise the temp faster than what the pump will do, I route the permeate, thru the heater and back to the wash tank.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.