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Mini-split outdoor unit indoors

Sifu

Sifu

SAWHORSE
Joined
Sep 3, 2011
Messages
3,318
I have had a rash of submittals for installing the outdoor units of a mini-split system indoors, in commercial office buildings, in a return air plenum above a dropped ceiling. I have asked for listings and manufacturer specs to verify the installation but have so far received nothing back. I received another one today, for 5 units. I have contacted that manufacturer (Mitsubishi) but not heard back yet either. So I figured I would see what this community thinks. These are mostly for server rooms. My concerns are the product itself and the materials within it being plenum rated, the potential for leaks in the spaces remote from and out of sight of the room, and the associated equipment, such as condensate pumps and drain lines, pipe insulation, control wires, etc. I am assuming the additional heat loads produced by the units are factored in by the engineer. Has anyone permitted this before and if so based on what criteria?
 
Your concerns are on point, If the chiller component is not located on the exterior then how is it to vent heat? Also condensate pans can be a source of moisture collection and based on filters specified can breed mold.
 
Plenum...absolutely not.....Beyond that I would also look for install instructions....Bad idea to install it inside, but not sure I could come up with a code section...
 
Well, I have written letters to 3 of the engineers who submitted. The first one has not been able to provide anything from the MFR that allows it to be installed in a plenum, and the MFR specifically said they do not have a unit that can be installed in a plenum. They are going to resubmit to remove the unit. I suspect that is going to be the case with the other MFR's but I will wait to see who can provide what.

I agree it seems like a bad idea to put the condenser inside, but I am not sure we can turn it down because it is a bad idea. I think the plenum issue goes beyond the bad idea aspect, and unless they can prove me wrong I think the code prohibits it.
 
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