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Community and Q&A

New minisplit smells

this_page_left_blank | Posted in Mechanicals on

I installed a Senville concealed duct minisplit a few weeks ago, had a professional vacuum it and check for leaks, release the refrigerant, etc. Over the last few days I’ve noticed an odd smell; not even sure how to describe it other than synthetic chemical like. I can smell it throughout the house, and it took me a while to determine the source. It’s definitely strongest in the air stream coming from the mini split (no ducts are installed yet, just blowing into the hallway).

I read that R410A has a faint ether smell. My wife works in a lab and tells me it doesn’t smell like ether.  The way the condensate drains is a little weird, with a port on either side, one plugged and one with a hose leading outside. The directions didn’t say anything about sloping, so I just have it level. This means that there’s a fair amount of water in there all of the time; I can see liquid water in the tray below the heat exchanger; there’s a neoprene weather stripping between the heat exchanger and the tray, so water can pool there until there’s enough to dribble to channels on either side. I pulled out the plug on the opposite side, and a fair amount of water poured out. Having said all that, we both agreed the smell doesn’t seem musty or moldy. I sopped up the standing water in the tray and it has no detectable odour.

Any ideas? Should I slope the unit to encourage draining, even aside from this current smell issue?

I took a picture to illustrate what I’m talking about, and in doing so noticed something else (second picture): corrosion on the galvanized metal near the bottom of the heat exchanger.

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  1. Expert Member
    BILL WICHERS | | #1

    You may just be smelling “new appliance smell” which will go away after a while. You generally won’t be able to smell refrigerant unless the leak is so severe that the unit will not be operable after a day or two.

    I wouldn’t slope the entire unit, but you may be able to slope the condensate pan a bit using a washer or two as shims on one side. It doesn’t take much to get the water to drain. Sloping the entire unit will slightly change the loading on blower bearings and isn’t a good thing for longevity of the unit.


  2. Expert Member
    AKOS TOTH | | #2

    Most (if not all) ducted units have both a condensate pump and a condensate drain. Usually I use the pump, which means blocking the lower drain. No matter which one you use, the units are mounted level.

    With the pump, there will some water in the drip pan, that is perfectly normal.

    I'm pretty sure what you are smelling is the coating on the coil (most coils come with some specialty coating), it should dissipate in a day or two.

  3. this_page_left_blank | | #3

    This smell appeared a few weeks after installing, and has persisted for about a week now.

    1. Expert Member
      BILL WICHERS | | #4

      Might be related to moisture then. Try putting a little bleach in the condensate tray. Don’t overdo it, maybe a teaspoon or two depending on how much water is in there. That should clear up anything that was growing. Stuff growing in condensate usually makes a “cool musty” smell, but that’s so subjective I don’t know how well you can compare it to what you smell.

      Another thing to check is foam rubber insulating materials around anything that gets hot, which may include reheat coils if you have a dehumidifier mode. If you smell a pungent chemical like smell I’d suspect something getting hot (check around the control board and the liquid side of the refrigerant line set). If you smell musty/swampy smell, then I’d suspect something is growing in the condensate pan or coil.

      You can get coil cleaners but there usually corrosive so they etch the fins of the coil a little every time they’re used. You don’t want to do that more than you need to. Commercially I recommend no more than once a year to my customers, and less than that if possible.


      1. this_page_left_blank | | #5

        The smell may have corresponded to when I switched from cool mode to dry mode. I will try switching back to cool mode and see if that changes anything. Another thing I did recently is apply the insulation (manufacturer supplied) over few inches of line set and fittings next to the unit.

        1. Expert Member
          BILL WICHERS | | #6

          If you have electric reheat coils and those came on to help with dehumidification, they may have burned off some oil or dust. That can sometimes make a smell, but it should go away after a while.


    2. HoverDA | | #7

      This is very normal. I installed two concealed duct mini splits from GREE last Fall. Used the whole winter for heating and there wasn't any smell at all. However, when I started to use them for cooling in May, I can smell something coming from the indoor units.

      Why is there a smell from the unit? Most likely, bacteria grow on the evaporator fins and in the condensation water pan. It becomes worse in the summer if you used the unit to heat in the past winter, since when the unit does heating, dust and bacteria accumulates on the evaporator fins. And when the unit starts to do the cooling, the condensation washes the evaporator fins and both dust and bacteria drops into the water pan. Since there is always a small amount of water left in the condensation water pan during the cooling season, with water and dust as food, bacteria grow quickly. Then you'll feel the smell.

      How to resolve this? First, just run the unit for cooling or in dry mode for a long period in a humid weather, the condensation will help you to wash and clean the fins and water pan. Second, spray some bleach on the fin and water pan and then clean them with brush, which kills the bacteria more thoroughly.


  4. BFW577 | | #8

    Both my Midea and Gree have a self clean mode. I think Senville is a rebadged Midea. Check your remote you might have the feature.

    From what I can tell it runs in dry mode to wet the coil and then reverses refrigerant direction and heats the coil to a high temperature to evaporate it. I run the self clean in mine occasionally and it seems to work.

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