In one room I need to cut groove into a wall to accommodate a condensate drain from a minisplit air handler/evaporator in an adjacent room. I know I could use a pump but I rather rely on old fashion gravity to transport the condensate to a drain, but in order to do so pass through one room's interior wall on a downward slope. What would be the best way and/or tool do so ? Any advice on how to also protect the drain from getting pierced in the future from a nail/screw. Probably shouldn't worry too much about it but rather avoid it if it is worthwhile. For the tool, I was thinking of a 4" grinder.

Thanks in advance!

  • Nail plates over the slot but do you really need 2” are you bringing down the line set and power also? I would probably want to remove the lath and plaster from that wall, bore holes for the drain in each stud at an angle until outside. Drop the line set and control wires through the floor and out to the pump then put up sheetrock. I don’t like lath and plaster I would rather remove it then there is 1 less wall that has lead paint on it if looking for a positive. If you want to cut a slot a skill saw would be my choice , check the wall for live circuits with a stud finder with a circuit alert.
    – Ed Beal
    May 12, 2020 at 22:20
  • Do you want to cut a channel in a wall or do you want to drill an angled hole through a wall ? For the latter you would just use a long drillbit.
    – Alaska Man
    May 12, 2020 at 22:39
  • @Ed Beal - I was hoping to run the line set w/power comm on top on the ceiling - but maybe since I need the channel for condensate might be easier to fit the line set in there. I was worried about someone later piercing the line set with a screw or something. Can I get a steel plate to run the length to protect it. I was hoping to grinder through the drywall (and plaster and lathe - I put a quarter inch wall drywall on top- lazy). The wiring I did so I know what behind the wall. I was thinking to notch the studs and ideally plug the cut wall back in place.
    – ecco88
    May 12, 2020 at 23:34
  • @AlaskaMan - I was hoping to not take out much of the wall and a channel ( is that is the correct term) would allow me to place the pipe in - plan to use pvc if possible for the drain and maybe even the line set.
    – ecco88
    May 12, 2020 at 23:38
  • Run the line on wall surface or use the pump. Pumps are very reliable and if the power goes out the unit will not be generating condensation.
    – Kris
    May 13, 2020 at 1:24

1 Answer 1


If you use a circular saw a straight pair of lines can be cut. Then a simple wood chisel with a sharp whack will remove the block to make your channel. Steel nail plates used for electrical will protect where the lines are trapped by the studs. In between the studs push the line set back an inch so distance will be protecting it if you run the line set with the drain.

I would suggest your control wire for the wire beside unit be run in the channel with the drain. This way the line can be identified later with a stud finder with voltage alert. I agree with gravity drains as I have seen many pumps fail.

  • Thanks Ed - is there a certain blade I should use haven’t looked into it yet.
    – ecco88
    May 13, 2020 at 13:23
  • 1
    I would use a cheap one as you might hit a few nails when I say cheap I mean a cheap carbide tipped framing blade , less teeth less expensive and they still cut after hitting a nail or 2 for the most part.
    – Ed Beal
    May 13, 2020 at 13:34

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