Any HVAC pros? - mini split line set question.

I am converting a cargo trailer to a camper and am planning on putting a mini-split AC/ Heater in it. I plan to mount the compressor on th tongue and run the lines inside. I would like to run the lines under the nose of the trailer then up through the floor. I am wondering if I can run the lines lower than the compressor inlets / valves or if the lines need to always be higher up. I think I read something about possible oil collecting in them if they are lower? I have attached a very rough drawing showing what I am talking about.

I wanted to run the lines underneath so as to keep it neat and not have to put a hole in the front of the trailer for the lines to go into.

 

First several times cond unit is on roof so no that doesn't matter, but the oil loop trap can if excessive but one loop should be fine. My concern is the pounding the unit will take on the road. Good luck with leaks.

 

I’ve seen lazy installers who don’t have the proper tools just leave a full length line set coiled multiple times at the outdoor unit.

that said rigid lines on a moving trailer I think isn’t going to work long term. Why not a roof ac unit and a separate heat source?

why not run the lineset on the outside of the trailer. Most retrofit house applications are on the exterior….

 

I am on a camper conversion forums and there are a lot of people putting mini splits on their trailers. I asked my HVAC guy about vibration and movement and he said is shouldn't be a problem since the flare connections are tight and have nylog on them. The mini-split units are super quiet and I can run one off my generator since it only pulls @ 8 amps. The roof top units are twice the price and noisy.

 

What unit are you using? I love the mini splits in my house. I hate the ac units in my motorhome.

 

I’m getting ready to install my own mini split at my house. I’ve watched a ton of YouTube videos and read a bunch about it. I’m NOT a professional, so please correct me if you have better or different info.

That said, I was told to not leave giant loops of the line set coiled up. I also read that lengths of the line set that are horizontal can cause the coolant to pool even with the low-pressure vacuum. I did not see anything about the line set being partially below the compressor.

So, in addition to gauges and a vacuum pump, I will be cutting my line set and flaring the ends to make it the proper length with no horizontal runs of line anywhere.

 

I purchased a 12,000 btu AC /Heater combo from Home Depot. It was $800 . There are a lot of people doing this and if they didn't hold up I would think a lot of people would be complaining. There are a lot of these installed on food trucks and trailers too. Some people put them on the back of their 5th wheels and RV's to cool the bedrooms.

 

I wouldn’t be too concerned about the loop. Like you said, it is an oil trap but the lineset isn’t that long so I’m guessing you’ll have good refrigerant velocity to entrain the oil in the refrigerant and probably not have issues. In some installations with long linesets (usually when the compressor is located above the evaporator) a trap is installed in the suction line at the first 20’ of vertical rise and every 15’ after. As the trap fills with oil the refrigerant will eventually carry it away as a slug of oil. Your biggest concern installed this way is probably a slug of oil from the trap entering the compressor in one shot which it won’t like, but the scroll compressors are pretty tough and can handle a little slugging. I do agree with the sentiment that the life of the outdoor unit will be shorter installed on a trailer seeing highway speeds as compared to stationary at a building. I’ve seen it.

 

Don't do Crack.
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From YouTube. Wrong. Advise people to not watch videos of first time installers bragging about ease of installation. Usually wrong. Weird how quick connect fittings and flares disappeared years ago from ice machine remotes and walk-ins for high fail rates only to return to mini splits.

 

Any coil I need would be horizontal and not vertical. The small "trap" in the line from the compressor to underneath the trailer would only be a 6 inch dip or so.