View Full Version : Split system increasing humidity

06-07-2017, 08:30 AM
Ok so following on from the repair of my unit B&Q chinese special I have made the following observations. The system is rated at 9000 btu, room is 12 sqm and is south facing with one external wall. Last night the starting temp was 28c, set temp 22c. Humidity started at 48 and this morning was 68. Fan speed was set to auto. Room feels very very comfortable , i my mind it seems to cool the room very quickly (so maybe thats the issue). This morning room temp was 22c (expected) but humidity was 68. Obviously this unit has no dehumidifier properties is a very simple unit so perhaps thats the issue with buying cheap. Will try again with fan speed on low. Anyone got any observations, could it be a low charge level or is this just par for the course. The temp is being dropped so any moisture holding ability of the air will be less so if humidity not being controlled then the moisture carrying capabilities of the air in the room will be less not that the actual room has more moisture. Are these thoughts valid?

06-07-2017, 10:01 AM
Just had the unit on dehumidifier mode for 45mins and it has dropped to 52RH room feels freezing temp is 19.7 indoor coil was dripping and outside drain dripping. Not sure how the de-humidifier mode works but it appears to ignore the set temp.

06-07-2017, 01:21 PM
That's correct they do ignore room temperature in an attempt to hold humidity.

Regarding your first post you are also correct. The operative word being RELATIVE humidity, as the temperature changes so will the %RH as it is not being controlled.

Air movement over your body will help with comfort feeling as it aids natural perspiration, can't beat a good ceiling fan ;)

06-07-2017, 03:14 PM
Ok thanks, when in the de-humidifier mode if I wiped my finger across the coil it was soaking wet but no frost so can I assume my charge is reasonable in the ball-park. System been in service for 6 or so years it is one of them quick fit systems so has never seen a professional. Glad I got it working after it packed up due to the thermistor. Has served me well considering what I paid for it :)

06-07-2017, 08:01 PM
Yep, sometimes you just strike lucky. ;)

06-07-2017, 08:55 PM
Humidity control is about the Latent Heat capacity of the evaporator coil.

Cheap Chinese unit may suffer in this respect.