How to run the drainline on a mini split

#1

Hi all,

I'm installing a mini split in my room-in-a-room construction. My interior and exterior units are about 15m apart, with the refrigerant tubes running through an attic and garage.

My question is what to do with the condensation drain line. I don't believe I can run it along with the refrigerant lines, because they f go up before they go down. Clearly if sound isolation was no issue, I'd just put a hole in the wall and run the drainline outside. But that would put a 1" hole through both of my leaves.

Does anyone have any solutions? Is it possible just to have the drain stay within the inner leaf of the room, and just drain into a recipient that I would empty physically from time to time?

Thanks in advance!

#2

generally speaking, you would run the drain line from the unit into the framing on your isolation wall(s) - similar to electrical etc. and from there to an approach receptacle - usually a gray water drain or exterior of the building. i usually like to see it drop fairly quickly (steep angle) if possible.

some things to watch for: potential for mold growth blocking it, so a one-way value is a good idea to keep the possible build up where you can clean it periodically, as well as flush the line regularly - every 6 months or so, or whenever you have it serviced.

on my home system we have a small condensate pump that is part of a PVC pipe assembly to provide acccess to clean the drain, and which ensures positive ejection of the water. might not be needed but check with your hvac installer for options.

you could have a receptacle in your room to drain to but it can become cyclic in that water you are condensing evaporates and becoming condensate again :-)

or you take time away and noone to empty it...

#3

Thanks Glenn!

Because of the climate I live in, and the construction materials used and my planned use of the room, I'm imagining that my mini split will be used 70% of the time as a heater and maybe 30% as an air conditioner. I'm I correct in assuming that only the air conditioning mode will create condensation? And presumably the opposite as well: that heating mode will dry the air?

#4

depends on the unit. also consider this - if you're in a hyper-insulated space with electronics and bodies - you will have heat and moisture :-)

so more than likely you will need some cooling cycles even in winter... i only know of a few spaces where cooling wasn't needed and both are near the arctic circle in winter w/ -20C temps outdoors... ;-)

that said, some dehumidification from a proper HRV could handle the heat cycle needs for reducing humidity.

#5

Glen, I'm ready to follow your advice, and just run the drain line outside on to the ground. However I've been trying to figure out how much water is going to come out, and it appears that between 5-20 gallons a day come out - this sounds enormous. My mini split is 2500w. If its 5 gallons per day, I would not want this to be emptying next to the foundation (I have a 200 year old house with a stone foundation build on compacted earth). However the installations I'm seeing around me just empty near an exterieur wall. I'm having trouble finding information on the topic.

Do I need to empty into a sewer system, or can this just drain into the ground ?

#6

like any water - you want it moving away from your foundation - so options include a sluiceway (plastic, cement, rocks) to direct it to a downslope, or if there is a rainwater / storm drainage opening, you could direct it there or near there.

example: i'm in Florida, so normal air humidity is 70-80% and my home is set to 50%, and even on the most moist days, i don't think we're extracting more than two gallons. and since the property is mainly sand-based, the drain just off the house is not really an issue - it simply get absorbed into the sand.

-- but -- if i needed to direct it, likely i would route it onto my concrete driveway (which is a downslope) and at the end of the driveway is a street level concave concrete channel (1-2") for water runoff into a storm drain (about 25ft away from the end of the driveway). so if you have something similar that could work nicely. if you have freezing weather though this might not be the right solution.

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