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Minisplit install questions

I am building a new house and planning to install a couple of minisplits. The air handler locations are going to be approximately 20' away from the outside condenser and located on interior walls. I am planning on bringing drains to these locations but my question is what size conduit should I run under the slab to accommodate the copper lines and electrical. I would also like to rough in conduit for another potential mini split down the road so is 2" large enough or would 4" be more appropriate.
Also I don't like the look of the "chases" that are often run down exterior walls to accommodate the line sets on retrofits.With new construction installs, is it advisable to sleeve the line sets in conduit inside wall assemblies.
Any insight would be appreciated.

Asked by Kye Ford
Posted May 18, 2014 6:08 PM ET
Edited May 19, 2014 5:50 AM ET


4 Answers

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To accommodate line sets + drain + wires would require larger than 2" .
If your interior walls are built using 2X4 , try and find some 3.5" conduit , if impossible use 3"
but running the linesets in 3" might be a bit tricky depending on the insulation size.
( which depends on the brand and sizing of your equipment )

Always install as large conduit as possible.

Running the linesets inside a conduit is not mandatory though,
as they are already insulated.

You can use old plastic 1/2" tubing for the drain, don't forget to make a water trap in the lines.

There is also no problem in having the linesets going out close to the exterior unit instead of at the ceiling point.

Why go under the slab ?? why not in the ceiling joists space ?

Answered by Jin Kazama
Posted May 19, 2014 12:48 AM ET


Thanks for the response Jim. We are building on a slab as the water table is high and the home is a one story so I was trying to give myself flexibility in the future to add another mini split location. So I figured if I bury some conduits now it will be a lot easier later.

I'll take your advice and go as big as possible.

Answered by Kye Ford
Posted May 19, 2014 2:21 PM ET


Remember the drain is a drain and must slope. Also IIRC mitsu instruction sheet is not in favor of traps, and I have had to remove at least one to make it drain properly. Put a screen in to keep the bugs out

Answered by Keith Gustafson
Posted May 19, 2014 7:45 PM ET


Keith : what was the problem with the trap ? Been installing with traps all the times and never had a single issue .

Answered by Jin Kazama
Posted May 20, 2014 12:15 AM ET

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