A/C Problem - Too much BTU

[SoFarAndNear]

Hello,

I recently bougth 2 A/Cs from HomePro. This model http://www.samsung.com/th/consumer/home-appliances/airconditioner/split-type/AR13FVSEDUVNST . I am using the A/Cs in one room with about 15sqm and another room with about 10sqm.

The thing is now when I am setting both A/Cs to the same setting. 24 degree (celsius) I got different results of temperature. The funny thing is that the A/C in the bigger room (14sqm) is colder then the smaller room (9sqm). Only if I am set the A/C in the small room to about 21 degree I got about the same temperature in both rooms.

My GF called the technican from HomePro and they just told us that the 12k BTU A/C is simply too strong for a 9 sqm room. Not sure if I am understand her correctly but as far as I understand the 12k BTU lets the air circulating to strong in the room.

Someone here at the Forum can confirm that? I just have a feeling the technican just dont want to come. My guess is that the thermometer in the A/C in the smaller room is not working correctly and just show around 3 degree colder then it really is. So when I set it to 24 degree it just cool it down to 27 degree.

Edited January 8, 2014 by SoFarAndNear

[Crossy]

OK, your A/Cs are certainly oversized even by the somewhat enthusiastic HomePro sizing table (600 BTU / m²). Who sized and specified the units for you?

Firstly I'd go and get one of the cheap digital thermometers and measure the temperature that each room is attaining relative to the thermostat setting, using the same thermometer in each case will ensure you are not misled by differences in the measurement device. If the thermostats are inaccurate, no worries, just set to whatever temperature needed to achive your requirement.

Do the rooms 'feel' to be different temperatures? The usual effect of having an oversized A/C unit is lack of de-humidifying action, so the room feels cold and clammy.

EDIT I note that these units are 'inverter' models, so they should adapt themselves to the required cooling rate and the comment regarding oversized units is less valid. Just use an independent instrument to check actual room temperatures.

[SoFarAndNear]

It is a new house. They engineer told me I will need 12k BTU for the bigger room and 9k BTU for the smaller room. The thing is that the 12k BTU model was on a big discount promotion and even cheaper then the 9k BTU. 9k BTU 21.000THB and 12k BTU 17.000THB. So I did ask the salesman at HomePro if I would use 12k BTU in the smaller room. He told me that this would be no problem and power usage not much more then 9k BTU model.

I am living in Thailand now for years and I always keep my A/C's around 24 degree. I know it sounds little bit impertinent but I know defintely know without any thermometer that the smaller room is warmer then 24 degree.

So you are saying an oversized A/C would make the room clammy? Ok that is really my point. Becasue the technican told us that the oversize makes it even warmer. Anyway after second call he will come later.

Edited January 8, 2014 by SoFarAndNear

[Crossy]

Please read my edit regarding inverter units.

Up to you of course but:-

The human body is notoriously inaccurate when measuring temperature, even a draught can make you feel cooler. A humid room may feel warmer (or indeed cooler) than a room the same temperature with lower humidity. Different people may experience these effects to different degrees, your tech. may not experience the same feelings you do.

A thermometer is not influenced by draughts and other factors so you will both experience it in the same way.

[BudRight]

There is no 'too much BTU.' The damn thing comes with a thermostat that turns it on and off. If you find it too cold then turn it up a couple degrees as the thermostat may not be calibrated correctly.

[Thighlander]

you will get frost on the windows or condensation if the unit is too big. Do you have different fan speeds? Have you considered a ceiling fan in the hotter room?

Also, on your remote, you likely have a differential setting, which sets the amount it is to be above the target before it kicks on. If it goes on and off too much , or short-cycles, then move it to 1.5 or even 3 on some units. It waste a lot of energy when it shortcycles.

Super high seer ratings are unnecessary in a place like thailand that is very hot and humid.

Edited January 9, 2014 by Thighlander