Minisplit condensate drain location
I’ve got two mini-split units (ducted 2nd floor and ductless 1st floor), both installed on the interior of the house. The refrigerant lines are to be routed down through interior walls to the basement, then out through the rim joist to the exterior units. The condensate lines will be gravity drained through the walls as well, but I’m trying to decide where to take them once they get to the basement — I can’t go out the rim joist with the refrigerant lines because it wouldn’t be sloped properly (and I’ve never liked just dribbling it out the side of the house either). The options are:
1: There is a sanitary sewer line running alone one basement wall, on the same side of the house as the mini-splits and where the refrigerant lines will be run. There is a 2″ line that comes out of that for a secondary sink in the kitchen that is conveniently located. I could tap into that, add a trap and an air gap, and drain the condensate lines here. The two potential issues are (1) the trap could be at risk of drying out in the winter, and might need a trap primer, and (2) plumbing code vent rules are tricky to understand but I think technically I’d need to install an AAV to vent the trap — even though the trap itself would be near the ceiling and the only other thing on that sewer branch is a sink on the floor directly above. Seems like a lot of complexity for a dribble of condensate!
2: Run the condensate lines to the middle of the basement, down along the wall in the middle, then around and into a utility sink in the corner of the basement (that subsequently drains into a floor drain). This is running condensate line quite a bit further, but eliminates all the extra trap / air gap / vent stuff.
3: Run condensate lines down to the floor, around the edge of the walls, and then across the floor to a floor drain in the middle of the room. This is basically what HVAC people around here do with standard A/C condensate lines, but I kind of hate it — especially since I might at some point insulate / finish the basement walls, and I don’t like tripping over pipes running across the middle of the floor either.
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Replies
I had the same problem and rain the drain to my utility sink. Added about 20ft but then I have no worries of a trap drying up (it will) or bacteria working jts way up the drain from rhe sewer line
I ran the refrigerant lines to the attic and across to the aide of the house and down.
I have found the drains dislike traps, even when 10 feet below the unit. I would drain them like a washing machine drain, tucked into the end of a larger drain.
I would 2nd the washing machine riser, one of the better spots for it. Utility sink also works great. With long runs like that make sure you don't have any sagging as this can create a p-trap which will prevent your condensate from draining. Use PVC or well supported PEX.
If you want to use the floor drain, you can notch the slab, run the line there and grout over it. The drain line is now also bellow the grate so it can all sit nice and flush. Pretty quick job, I have a 7 1/4" circular saw I don't care about on a GFCI cord with a 7" diamond blade that works great for something like this.
You definitely don't want a dedicated P-trap just for the minisplit. This will always dry up in the winter.