Prevent line set condensation
1869farmhouse
| Posted in General Questions on
I installed a mini split system in my ancient farmhouse. For one of the air handlers, I had to go between two interior walls and the only way in without cutting petrified 2×6 studs was a small gap.
I removed maybe 4” of pipe insulation to make it fit, thinking to myself this couldn’t possibly effect efficiency.
Well, I didn’t consider condensation and now it’s dripping and causing a mess. Is there any way to prevent this without tearing out the sheetrock and finding a new place to run the line set?
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Replies
No way around it. The line set must be insulated.
You need to insulate both lines. Make sure the pipe wrap you use is not the standard cheap hot water pipe insulation but proper line wrap. It should have a flap at the seam to seal, very important to have an air tight seal to prevent condensation.
I only have a high level understanding of dew point, but the 4” of exposed line set is in the wall cavity. In theory, if both the interior and exterior of the wall were insulated well enough, wouldn’t it be possible to keep the air below the dew point?
It will never be tight enough. You can spray foam the entire cavity, which will work, but pipe insulation is much simpler.
Good call, I didn’t think about pumping the whole cavity full of foam. Thank you. I know pipe insulation sounds simpler, but in this situation, it would be a pretty massive undertaking.
If you can form a Barrier around the line set, such as with a piece of large PVC pipe cut in half, you could then fill the area inside the barrier with canned foam to encapsulate the line set. I’ve done similar things before to sleeve the line set through walls. It surprises me that you think pipe insulation would be more difficult to install though.
Bill
It’s a matter of placement. My only option was to run in between two interior walls from the exterior. In addition to that, the only way is was to tuck between these 2 ancient/petrified 2x7 boards. I didn’t want to cut them, so I removed a tiny section of pipe insulation to fit. So insulating the pipes normally would involve not only sheetrock repair, but also cutting these ancient studs and reframing structure to make up for that. Crazy, I know haha
I've been told that unlike conventional systems, mini-splits have the expansion valve in the outdoor unit (for noise reasons), meaning that the supply line to the indoor unit will be quite cold (effectively it is part of the evaporator). The return line has no phase change, so less of an issue with either design. Is this true - mini-splits need much more attention to supply line insulation?
Makes sense. Would love to hear confirmation. The amount of condensation from this 4” length of line set is mind blowing.
I've just had a similar issue with a mini split at a job site. The HVAC contractor installed a mini split the same way as a standard AC unit and did not insulate the supply line. Within minutes of running the unit, water was dripping down onto equipment from condensation on it. Needless to say, they had to come back an insulate the line.
With mini splits, all lines need to be insulated and well sealed. There is no way around this.
Hey Austin. I'm in a similar situation with a line set running down an old interior wall that's hot and humid.
What did you end up doing exactly? I know I need to insulate the lines better but not sure with what (product) yet.