condensation on drain line

[LRAC]

Hi all

This may sound simple but our guys have started to report condensation dripping on the drain outlet of Fujitsu compact cassettes units, i,m not sure but surely the water coming out is above 10 C as its been siting in the drain pan.We do insulate the drain lines if concealed by a plaster ceiling, otherwise we don't.

Any explanation much appreciated.

regards
LRAC

[Peter_1]

How have they connect it to the drain? With a small plastic tube.?
Is it only on the metal piece coming out sideways the pan?
Is it sloped towards the sewer?
Most AC's have un underpressure in the drainpan, don't forget this.

[LRAC]

Hi peter nice to hear from you,

AC unit exits in 32mm clear plastic and we reduce this down too 22mm in plastic and it slopes down too the drain perfectly ok.

Is it another a/c mystery that us fridgy's just don't understand because were too wrapped up in decent stuff with no fault codes to work off?

P.S only been belgium twice and that was when i was young doing the school trips in Ostende,do the lady's still sit in the windows for kids to look at?

regards
LRAC

[Brian_UK]

Yes I have seen this before, remember that the conditions in the ceiling void are often condusive to high relative humidity compared with the conditions of the drain pipework.

The drain pumps themselves are also within the cold airstream of the unit sometimes which also doesn't help.

[Abby Normal]

Suspended ceiling and you are using cassettes. Therefore unlikely it is a plenum ceiling.

However, maybe some leaky exhaust (extract in queens english) ducts , and the ceiling space is negaitive pressure with respect to the outside. If the ceiling is under an attic or the space extends to an exterior wall maybe negative pressure is drawing ambient humidity into the ceiling space.

Perhaps wind driven infiltration.

Is it possible that the dewpoint of ambient air is higher than the temp of the drain lines?

[monkey spanners]

Have seen this with a cassette we installed in a show room for water coolers. The cassette itself, its drain and the pipework all sweated due to the high humidity caused by the bottling plant out the back in the warehouse (bottling plant not installed when we fitted the cassette, honest, probably wouldn't have realised anyway ) All they do is filter mains water and fill those 20L plastic bottles for water coolers, so much for mineral water! Had to insulated the drain line, reinsulated the fridge pipes and i think we armaflex taped the cassette.