Mini Split HVAC unit installation elevations

[NorCA]

Hi Guys,
I have seen a ton of mini split installations where the outdoor unit is located outside of a building near the ground, and at a lower elevation than the indoor unit (which is high up on a wall). As such, most of the installation instructions say to have wall penetrations go down at an angle etc. to install properly.

I have a scenario where I would like to mount the outdoor unit at a location higher than the indoor wall mounted unit by about 8'. Think basement room, but with outdoor section up at grade level above.

The installation instructions I have dont seem to acknowledge this scenario and are catered to the more conventional installation. Unit is a 36K BTU with heat pump inverter type by Mr. Cool, DIY type.

Anyone know if this will create any issues for me? It would seem an elevation difference of 8' should be nominal but I don't want the R410 sitting in the indoor unit because it is lower than the outdoor unit. In full disclosure I'm no HVAC expert, so thank you for the help.

 

[chrispyny]

The penetration still needs to go down at a slight angle for condensation draining, and the units manual should quote min max height differences allowed. I dunno about the diy splits, but mitsu and fujitsu maxes are like 45' so you should be fine.

 

[Jackfre]

The reason they call for the "grade to the outside" is for the condensate drain line. The refrigerant doesn't care about the elevation. Is your basement subgrade? If so you need to figure out a drain configuration that allows gravity drain, to a laundry sink or washing machine drain pipe for instance. Provide an air gap for that. If you are unable to gravity drain you will need a condensate pump. Aspen makes a nice mini-condensate pump, or you can run your drain to a more remote location and use a larger condensate pump. If you have a sump pump, that would be a good location.
If subgrade it must be a heck of a big basement for 36kbtu.

 

[NorCA]

The reason they call for the "grade to the outside" is for the condensate drain line. The refrigerant doesn't care about the elevation. Is your basement subgrade? If so you need to figure out a drain configuration that allows gravity drain, to a laundry sink or washing machine drain pipe for instance. Provide an air gap for that. If you are unable to gravity drain you will need a condensate pump. Aspen makes a nice mini-condensate pump, or you can run your drain to a more remote location and use a larger condensate pump. If you have a sump pump, that would be a good location.
If subgrade it must be a heck of a big basement for 36kbtu.

Good info Jack, that makes sense. The unit is actually for my barn/shop, but I gave the basement analogy to help explain the installation condition. I shouldn't have a problem dealing with the condensate, I have a sink right next door.

 

[NorCA]

The penetration still needs to go down at a slight angle for condensation draining, and the units manual should quote min max height differences allowed. I dunno about the diy splits, but mitsu and fujitsu maxes are like 45' so you should be fine.

Ok, thank you Chrispy.

 

[rlitman]

The reason they call for the "grade to the outside" is for the condensate drain line. The refrigerant doesn't care about the elevation. Is your basement subgrade? If so you need to figure out a drain configuration that allows gravity drain, to a laundry sink or washing machine drain pipe for instance. Provide an air gap for that. If you are unable to gravity drain you will need a condensate pump. Aspen makes a nice mini-condensate pump, or you can run your drain to a more remote location and use a larger condensate pump. If you have a sump pump, that would be a good location.
If subgrade it must be a heck of a big basement for 36kbtu.

Well, mostly.

The wall penetration must be at the lower level of the unit, sloping down. This is for condensate to be able to flow freely, but also because a wall penetration sloping down prevents water from following the lines and entering the wall. Because of this, even if the outdoor unit is vertically above the wall penetration (if it is wall mounted for example), you will want the lines to exit the penetration on a downward slope (a drip bend) before they head upwards to the outside unit.

And the wall penetration must be daylighted. So, if the unit is mounted on the wall beneath ground level, you'll either have to make something like a window well (and have appropriate drainage considered), or you could divert the condensate into a lift pump, and run the refrigerant lines up inside, to an above ground opening.