Pioneer mini split line insulation sweating

[tmshort]

New install of a Pioneer 18KBTU unit in my shop.
It is working great, quiet, COLD air.

The lines are installed with the supplied insulation, all is sealed up well etc.

I have not snapped the line covers on over everything yet, was out back just now and the insulation is sweating like crazy. It is 90F and very humid here today, the insulation is quite cool to touch (the lines, obviously, are COLD).

Is it necessary to insulate more than what is supplied? If so, any recommended products?

 

[chinboys]

The liquid line (smaller of the two) shouldn't be cold but warm or hot as it exits the condenser unit heading towards the evaporator. The liquid freon them expands at the evaporator where the coils of such will get cold and the gas phase leaves via the larger pipe towards the condenser.
This is where moisture forms as well as at the evaporator coil where a condensate pan collects the moisture to be piped away.
Is the insulation split along the length of the return line? Get some insulation tape to seal the seam, And make sure the insulation is wrapped up tightly at the end where it exits the evaporator and condensate pan. And perhaps get additional pipe insulation or tape to wrap over the areas where the sweating occurs (which may be the whole length of the return line, especially at both ends (evaporator and condenser).

You may find sweating initially when the unit starts up in high humidity but as the cooling and humidity drops... no more sweating.

 

[metlmunchr]

Both lines are cold when a mini split is in cooling mode because the expansion valve is located in the outdoor unit rather than adjacent to the evaporator as in a normal split system.

Re the original question about the insulation sweating outdoors... Assuming you're using the line cover set supplied by pioneer, once you install the covers and seal off the openings at the top and bottom with the modeling clay stuff Pioneer includes with the unit, the sweating should stop.

 

[tmshort]

Correct on the both lines being cold with a minisplit.

Mine is sweating uniformly along the entire length of the 22' or so of insulated tubing, not just near the ends. The insulation itself is cool to touch relative to the outside air. I'm wondering if others have seen this, and if I should just disregard or try to further insulate the run of tubing.

I don't think closing up the plastic lineset cover is going to make any difference, that stuff is nowhere near airtight and the air inside around the tubing will be basically ambient temp/humidity.

 

[Terry D]

Did you add on to the factory line set that came with the unit, or did it come at this length. If this is longer than what came with the unit, you have to adjust the charge.

 

[tmshort]

Did you add on to the factory line set that came with the unit, or did it come at this length. If this is longer than what came with the unit, you have to adjust the charge.

”Stock” line length for these is 16’. According to the manual, the factory charge is good for up to 25’. I ordered a 25’ lineset but cut off ~4‘, so I am within spec for the factory charge.

 

[tmshort]

I’m considering options.
I am sorta surprised I am the only one with this finding ... I know there are tons of mini splits installed in humid locations.

One idea I’ve tossed around is setting up the line set cover then filling it with spray foam. This would create a nightmare if maintenance were needed down the road, however...

 

[Tracs]

I’m considering options.
I am sorta surprised I am the only one with this finding ... I know there are tons of mini splits installed in humid locations.

One idea I’ve tossed around is setting up the line set cover then filling it with spray foam. This would create a nightmare if maintenance were needed down the road, however...

Don't fill the line set cover with spray foam.

Maybe there is something wrong with the install or operation of your unit.

 

[Yankeefarmer]

I doubt very many people inspect their line sets after a successful startup. Your line set will have condensation on the outside if it’s surface temperature is below dewpoint. If the installation is in the shade, the outside surface temperature will be a good bit cooler than if it is in the sun.

 

[tmshort]

Don't fill the line set cover with spray foam.

Maybe there is something wrong with the install or operation of your unit.

I admit that I don’t know a ton about HVAC stuff, but have read a lot in anticipation of this project.

Is there a failure mode where it would work too well - i.e. the lines are too cold in cooling mode? The lines are cold, the unit puts out very cold air; when I run the system checks all are OK, and I have no leaks, etc.

 

[tmshort]

I doubt very many people inspect their line sets after a successful startup. Your line set will have condensation on the outside if it’s surface temperature is below dewpoint. If the installation is in the shade, the outside surface temperature will be a good bit cooler than if it is in the sun.

Makes sense. And mine are in the shade, as 80% of the run is under an overhanging roof / parking area on the side of my shop.

 

[hihowareyou]

Only one of my lines is cold ( the bottom skinny line ) when turned on cool. Both the outside and inside units are on and you can hear compressor turned on. Why ain’t I getting cold air ?
Disclosure : we had a lot of wind that put a lot of leaves in the outside unit and the inside filter was a little dirty.

 

[fitter30]

Only one of my lines is cold ( the bottom skinny line ) when turned on cool. Both the outside and inside units are on and you can hear compressor turned on. Why ain’t I getting cold air ?
Disclosure : we had a lot of wind that put a lot of leaves in the outside unit and the inside filter was a little dirty.

Probably short on charge.

 

[fitter30]

When the dew point is high in the condition space dew point should be lower than outside. Thicker sealed pipe covering would be needed. ArmaFlex is one brand.