Dripping Minisplit

[man from trane]

I've been doing HVACR for around 15 years but minisplits are somewhat new to me. I moved to the Caribbean a year ago and that's 85% of the market here.

Anyway, I saw this once on a cheap unit, could not find a problem, so I wrote if off as a fluke. Now it's happening to my own unit!

I have a 1 ton "Chigo", (Guangdong Chigo Corp.) 13 SEER, 410A unit. There is water dripping from the air outlet of my inside unit. It's only a month old.

Ambient is 82 Deg, 75% Rh. Inside is 75.2 Deg, 51% Rh. Discharge is 50.5 Deg. Fan is on auto, currently low speed. Suction pressure is 130 psi, suction temp at compressor is 66 Deg. In case you don't have your TP chart memorized yet that's about 21 deg SH at the compressor.

Unit was factory charged for 15 foot line set, mine is 8' so I removed "a little".

Coil looks clean, filters clean, drain line clear, pan is not backed up. Water droplets literally fall from the coil and get sucked into the fan, which blows the water out the front of the unit (carry over).

What do you think? :confused:

[skrewdriver]

I've seen this once on a mini-split, but it was dirty filters. Maybe you should speed up the fan and see if that helps.

[air2spare]

maybe its removing too much latent heat with the slow fan speed,those evap fins are very close together you know, try increasing the fan speed

[coolerinfrederick]

Ambient is 82 Deg, 75% Rh.




lots of moisture to remove, speed up fan like what everyone else is saying, another thing is i dont believe these units are designed to remove such a large quanity of condensation, i put one in a couple of years ago and had to go with a little toy lookin pump, had a great lift rating but coud only pump a small volume of water

[man from trane]

Speeding up the fan may stop the dripping, but then it gets noisy. I would definitely not be happy with that solution, and neither will my customers.

I think the problem might be a slight undercharge.

The dewpoint inside is about 55 Degrees. With 22 degrees SH, the coil temp is 45 Degrees throughout the first portion which gathers moisture quickly, but the portion of the coil that is 55 degrees and above is not removing any latent heat. Perhaps the difference in temp across the coil causes the moisture to not "stick" to the surface and fall on to the fan blade. Also, the droplets that form on the coldest part may be too large for the narrow fins.

I'm going to try charging to about 15 Degrees SH which should give me about a 49 degree coil and a more even temp across the whole surface.

I'll update with the results.

[beenthere]

What speed are you currently running your fan at.

[Jesus"]

increase your superheat, it will lower your rh on the coil. thats what i was told on walk in coolroom unit, same princables i would assume.

[man from trane]

What speed are you currently running your fan at.

Speed = "Auto". When I turn it on with the setpoint at 24, the room is around 28-29 and the fan runs at high speed. It goes to medium at 27 and when the temp drops to 26 it goes to low. The difference between speeds is very slight.

[man from trane]

increase your superheat, it will lower your rh on the coil. thats what i was told on walk in coolroom unit, same princables i would assume.

True, but it lowers the Rh by collecting more moisture on the colder part of the coil. With 20 FPI or whatever these coils are, that doesn't leave much room for run off. The SH is already plenty high. I'm going to try lowering it to 15 degrees and we'll see what happens.

I noticed that right now it's 77 degrees and 49% Rh and not dripping. Very sensitive, these cheap Chinese units. :mad: I can't complain too much; I paid less for my 13 SEER system with install kit included than I would have for a 1 ton window unit. :D

[JWB]

You still in the Virgins? I remember your cooler scenerio from last year when everyone was telling you to get the employees to shut the doors. No way, not down there. Those locals do not care what a refer guy thinks.My wife just got back from St. John. I'll end up living there soon. (3-6yrs from now.)

I was wondering in your post above if there was a manu oil on the coil that might make the water not really bond to the coil. I know it is goofy, but try cleaning it real quick.

[man from trane]

You still in the Virgins? I remember your cooler scenerio from last year when everyone was telling you to get the employees to shut the doors. No way, not down there. Those locals do not care what a refer guy thinks.My wife just got back from St. John. I'll end up living there soon. (3-6yrs from now.)

I was wondering in your post above if there was a manu oil on the coil that might make the water not really bond to the coil. I know it is goofy, but try cleaning it real quick.

There could be oil on it. I've run into that on a couple of large Trane AHU's in a chemical plant and it was causing carry over like crazy.

Yeah, I'm still here in the VI. I don't get to St. John very often but it's beautiful there and pretty quiet.

I gave up on the freezer doors. Let the health inspector handle it. I can't even get them to keep the sliders closed in the meat prep room. It drops below 65 degrees and they just can't handle the cold so they open half of the windows! I'm working in short sleeves in there and it feels barely cool! :rolleyes: Maybe they should hire Canadians to work in the coolers. :cool:

[man from trane]

All temps in °F, Fan Speed = High, Inside Conditions- 78°, 59% Rh. Ambient- 86°, 72%.

I added charge to reduce the Superheat from 21° to 14°. (I'm taking the temp reading at the service valve, but with only 8' of individually insulated line set it probably doesn't change much.)

This increased my saturated evap temp from 45°F to 48°F. The Delta T remained the same at 22°F. This tells me that the overall coil temp is warmer, but it's spreading out the heat transfer to a larger area of the coil.

I can't explain why, but the dripping stopped. It also seems to cool the place down a little faster. It started cycling at the 76° setpoint around 10 pm. Usually it runs steady until after midnight. This is a typical Caribbean structure, poured concrete, no insulation, glass jalousie windows minus seals.

Maybe the dripping problem is only a tropical climate issue, but I also saw it happen on an old Trane minisplit that was undercharged. When I charged it, the leak stopped.

:confused:

[lil' randy]

does te fan have autoswing feature on the blower flap, it may help if the vent flap is moving, also we find running 1/2 or 3/4 drain lline alswo keep condensate from collecting in the pan

[man from trane]

^ It might, but I don't like the flap on "swing", and I don't want it to wear out. the drain line was flowing perfectly.

No more dripping and it has been a week. Just a slight undercharge.