Condensation Issues

[Husky250]

Hi All,

I have a large property that has hundreds of Mini-Splits (wall mount Indoor units) installed in high humid conditions. The issue is abnormal condensation on the factory piping at the connection of the manifold of the Indoor.

At first inspection, I noticed all piping insulated seperately from outdoor unit to Indoor flare connections. I did notice on the factory side of the flares the liquid and suction pipes are insulated together.

I know a few items that would cause excessive condensation such as:

excessive piping lengths (over recommended)
dirty Indoor coils
air gaps between piping and insulation
excessive piping bends (creating pressure drops)
wrong piping sizes
refrigerant charge

But from what I have listed, is there any other things I should be checking? These usits are installed in a really high humidity area, and I also wonder if they are sized in proportion of the load.

I welcome and really need alot of comments as I know you guys know much more than I on these Mini splits.

Thanks to all who respond!

[stufus]

Hey Husky
I'd say you've pretty much covered all the base's there.
On these wall mount's if I'm not using an internally mounted pump i prefer to remove the factory insulation and individually insulate both pipes ,obviously before hanging it on the wall , and as you said a good air seal is essential,and be sure to wrap the flare nuts well.
with regard to the application a few more specifics would help,
The usual stuff,room size, load ,unit models , pipe runs etc etc
Happy Christmas
Stu

[Husky250]

Cheers and thanks for the reply!

In regards to the load I dont have specifics yet as I am preparing to do so. I just wanted to get some opinions if maybe mini-splits not sized properly for the space could cause excessive condensation on the factory piping. I do know they leave doors and windows open quite frequently whicj has me concerned.

Merry Christmas to you as well!!!

Husky




Hey Husky
I'd say you've pretty much covered all the base's there.
On these wall mount's if I'm not using an internally mounted pump i prefer to remove the factory insulation and individually insulate both pipes ,obviously before hanging it on the wall , and as you said a good air seal is essential,and be sure to wrap the flare nuts well.
with regard to the application a few more specifics would help,
The usual stuff,room size, load ,unit models , pipe runs etc etc
Happy Christmas
Stu

[stufus]

Hey Husky
The minis may well be sized correctly, time will tell:D
But the window and door stuff certainly wont be helping your cause any.:mad:
Leave a mop and bucket in each room,and inform the occupant if they don't want to close the windows and doors,they can mop the floors;)
Cheers
Stu

[nike123]

According to Armaflex if your humidity is 70% and pipe temperature is, let say, 4°C than insulation thickness for Armaflex AC should be 9mm to stop condensation.
Since in these units insulation thickness is rarely above 5mm and it is usually compacted (reduced thickness) at some points (especially at flares) there is obvious that condensation is inevitable.

[Husky250]

Thanks for commenting Nike!

I agree with your comment condensation is inevitble. Especially given with RH 70% or greater. With the professional installations you have done, what would be your suggestion to battle the condensation?

Thamks again !

Husky




According to Armaflex if your humidity is 70% and pipe temperature is, let say, 4°C than insulation thickness for Armaflex AC should be 9mm to stop condensation.
Since in these units insulation thickness is rarely above 5mm and it is usually compacted (reduced thickness) at some points (especially at flares) there is obvious that condensation is inevitable.

[nike123]

Units cooling capacity should be selected in such way that can keep humidity in conditioned space in acceptable limits (45-60%). That mean SHR of unit should be correct for conditions and humidity will be normal and therefore no need for special measures against condensation formation in indoor piping.
Also, these unit have dry mode to help in keeping indoor humidity under control.
Advise occupants to use that mode more frequently.

[PRESS]

Hi,

If you take care to look at the outdoor units of split units you will notice that both pipes are contain cold gas 4 deg C approxmately. My point is your expansion device is in the outdoor unit which is the raeson why we insulate both pipes. If you stop a moment and think that we would not neccessarily insulate a liquid line of a system under normal circumstances then you should figure out that both pipes form your low side and interstitial condensation is bound to haunt you if your insulation is not right.

I personaly wouldnt worry about the fact that the manufacturer supplys the unit with the pipes i one armaflex (insulation) because I know that the two pipes form part of the evaprator. However I would be so worried about whether the insulation is air tight.

You can do an indepth investigation on the sizing and application of your units by double checking specifications like the dry and wet bulb teperatures, relative humidity evaporating temperatures and air flows as compared to the manufacture's specifications to justify the question of sizing.

My suspicion is poor insulation workmanship from the installation is the problem you are facing here.

Best of chances.

[Husky250]

Thanks Nike and to all tht have posted!

Given the location of the condensation, at the manifold internal of the Indoor unit, I suspect humidity within the space in combination with other factors could be the issue. I also have received informaion humidity is high inside the space although I dont have an exact measurement.

I was also told the wall in which the piping was ran through is not totally sealed. That tells me possibly the warmer air in contact with he colder pipes could be causing heat transfer / thus condensation.

Is it safe to say that if the insulation is selected based on the ambient conditions, if the install and equipment is operating a designed, there should be no condensation even if the piping is inside the same insulation jacket of the factory side of the flare connections.

Thanks,






Units cooling capacity should be selected in such way that can keep humidity in conditioned space in acceptable limits (45-60%). That mean SHR of unit should be correct for conditions and humidity will be normal and therefore no need for special measures against condensation formation in indoor piping.
Also, these unit have dry mode to help in keeping indoor humidity under control.
Advise occupants to use that mode more frequently.

[nike123]

Is it safe to say that if the insulation is selected based on the ambient conditions, if the install and equipment is operating a designed, there should be no condensation even if the piping is inside the same insulation jacket of the factory side of the flare connections.

Thanks,
Yes and no!
Yes, if insulation on site is selected per actual site conditions.
No, because factory insulation is selected per their specified conditions, and not actual site conditions.