We're adding an addition (garage with master suite) and we currently have a couple of drain lines installed on that side of the house but they need to be moved to install the addition. Typically, they don't want to install these on the front of the house becausethe drain lines coming down are ugly but I was thinking that since we're having the entire house sided at the same time it might be possible to install the drain lines in the wall instead to avoid the ugly lines on the outside of the house? Is this an alternative solution I'm not seeing?

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    Look at it this way: all your hot- and cold-water pipes are in the walls already. If there's sufficient clearance & not a bunch of cross-braces to drill thru, then what's a few more water-carrying pipes gonna matter? Aug 21, 2020 at 16:49
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    I mentioned going into drains if your new plumbing drains go close to those locations you could drain into them but would make sure you have good access because it’s not uncommon for condensate drains to get plugged if not regularly cleaned (the coils and pan).
    – Ed Beal
    Aug 22, 2020 at 14:50

2 Answers 2


Yes you can run them in the wall. Most mini splits installed today have the drains and the high and low pressure refrigerant lines run on the exterior of the home so this is very normal and has been industry standard for decades to run the condensate out an exterior wall or into a drain. I would want to make sure the run was straight and you have the ability to clean it incase green gunkies grow in the line and creates plugs.


These shouldn't have been done outside the wall to start with. They can run in the wall just like everything else does.

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    They are always run outside as it's much easier and if they had to open up the wall to run them (remove siding, sheathing, etc) that would be very expensive. Aug 21, 2020 at 18:25
  • Man oh man, do these pipes just pop into the existence, so that when the house is built nobody knows that maybe just maybe those might come handy? If this is new-ish construction (last 20 years) - this is completely unexcusable stupidity. If this is a 50-year-old home then I might be willing to give them a break. These things don't have to be added after the fact, lol. Aug 21, 2020 at 18:28
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    Wow you have not been involved with very much construction have you? The last house I built has a condensate drain out the side of the home. Why? It is cheaper and code allows it. Who is going to pay 100+ dollars to put in a extra drain when the furnace is not located close to a drain they run it out the wall for 10$.
    – Ed Beal
    Aug 22, 2020 at 3:49
  • I thought I should add that air conditioning was not common until the 60’s it became affordable after ww2 with the boom in units by 53-55. Many of those early units were window units with central air becoming more popular than window ac units in the 70’s but still many homes still use window units. Today with mini splits many homes with all electric heating are converting to mini split systems as no duct work is needed.
    – Ed Beal
    Aug 22, 2020 at 18:38

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