Years ago: Lane Lloyko made a presentation about using Float Drainers on cold storage type coils....His study indicated that a flow Velocity was required to make condensate move in the evaporator tubes and this was identified for the specific tubes/fin arrangement and so on for those specific coils. This for a multitute of models and manufacturers of coils....

The resulting "overfeed" of hot gas was a small fraction of that which a regulator would pass after the "melt" was complete; but did depend somewhat on the coil circuiting and tube diameters.

I found this in the IIAR archives from 1982 presentations....