Aircon - Dry vs Cool modes. Energy efficiency benefits?

[samran]

All, so I've done some research and all that has happened is that I've become more confused on this issue as to whether there is any energy efficieny benefit of one over the other.

I saw one statement which intuitively made sense from Naam that you use dry mode in the wet and humid periods and cool mode when the humidity is lower (say Dec to April in BKK). Does that sound about right?

[Naam]

no... "dry mode in the wet and humid periods" does not sound right at all.

the "dry" mode is meant to be used only intermittently for short periods (1-2 hours) when the humidity in the room is too high. but that only happens when the aircon is used very sparsely. usually the dehumidification when in cooling mode is sufficient to achieve a comfortable level of 60% relative humidity.

using dry mode for an extended period of time puts an additional load on the compressor because the pressure in the system increases. and should the sensors (which monitor evaporator temperature and adjust fan speed) malfunction the heart of the unit (compressor) faces serious wear and tear if not damage.

my consultancy fees are 107 Baht (VAT included). please send by e-mail attachment

[khaowong1]

no... "dry mode in the wet and humid periods" does not sound right at all.

the "dry" mode is meant to be used only intermittently for short periods (1-2 hours) when the humidity in the room is too high. but that only happens when the aircon is used very sparsely. usually the dehumidification when in cooling mode is sufficient to achieve a comfortable level of 60% relative humidity.

using dry mode for an extended period of time puts an additional load on the compressor because the pressure in the system increases. and should the sensors (which monitor evaporator temperature and adjust fan speed) malfunction the heart of the unit (compressor) faces serious wear and tear if not damage.

my consultancy fees are 107 Baht (VAT included). please send by e-mail attachment

thank you, your checks in the mail.

[samran]

no... "dry mode in the wet and humid periods" does not sound right at all.

the "dry" mode is meant to be used only intermittently for short periods (1-2 hours) when the humidity in the room is too high. but that only happens when the aircon is used very sparsely. usually the dehumidification when in cooling mode is sufficient to achieve a comfortable level of 60% relative humidity.

using dry mode for an extended period of time puts an additional load on the compressor because the pressure in the system increases. and should the sensors (which monitor evaporator temperature and adjust fan speed) malfunction the heart of the unit (compressor) faces serious wear and tear if not damage.

my consultancy fees are 107 Baht (VAT included). please send by e-mail attachment

Thanks. I can only afford 106 baht though....

[Maestro]

The way I understand the "cool" and "dry" modes, they work like this:

"cool" mode:

The aircon was off and the room temperature is 30 °C, relative humidity is something like 90% (during the rainy season). The aircon's thermostat is set to 25 °C. You switch on the aircon, the fan starts to run and the compressor cuts in. Within about 10 minutes the relative humidity goes down to 60% because the air passes through narrowly spaced lamellae which cause the humidity to condensate and flow out as water. When the room temperature goes down to 25 °C the compressor cuts out but the fan continues to run and within about 10 minutes relative humidity shoots up to 90% because the air passes over the water drops remaining caught between the lamellae. When the temperature rises to 26 °C, the compressor cuts in again and the aforementioned cycle repeats itself.

"dry" mode:

The aircon was off and the room temperature is 30 °C, relative humidity is something like 90% (during the rainy season). The aircon's thermostat is set to 25 °C. You switch on the aircon, the fan starts to run and the compressor cuts in. Within about 10 minutes the relative humidity goes down to 60% because the air passes through narrowly spaced lamellae which cause the humidity to condensate and flow out as water. When the room temperature goes down to 25 °C both the compressor and the fan cut out, relative humidity increases only a little and slowly based on humidity emanating from living organisms in the room (persons, animals, plants) and water containers in the room, humidity entering through non-tight window frames and below doors. When the temperature rises to 26 °C, the fan and compressor cut in again and the aforementioned cycle repeats itself.

[craigt3365]

no... "dry mode in the wet and humid periods" does not sound right at all.

the "dry" mode is meant to be used only intermittently for short periods (1-2 hours) when the humidity in the room is too high. but that only happens when the aircon is used very sparsely. usually the dehumidification when in cooling mode is sufficient to achieve a comfortable level of 60% relative humidity.

using dry mode for an extended period of time puts an additional load on the compressor because the pressure in the system increases. and should the sensors (which monitor evaporator temperature and adjust fan speed) malfunction the heart of the unit (compressor) faces serious wear and tear if not damage.

my consultancy fees are 107 Baht (VAT included). please send by e-mail attachment

Thank goodness it wasn't ++!!

[ya5702]

To Admin. You explained the difference between Dry and Cool mode very well. Simple to understand.

However, from my observations of my Daikin split-type air-conditioners, the Dry and Cool modes work the reverse of what you said i.e. in Cool mode the compressor and the fan cut out at the preset temperature; in Dry mode the compressor cuts out and the fan continues to run.

[jombom]

Most efficient of all is to switch it off. Tit get used to it ---- adapt.

[Maestro]

...from my observations of my Daikin split-type air-conditioners, the Dry and Cool modes work the reverse of what you said i.e. in Cool mode the compressor and the fan cut out at the preset temperature; in Dry mode the compressor cuts out and the fan continues to run.

It could be that that some aircon manufacturers implement it differently or that an individual aircon unit's relay is wired incorrectly. My observations were based on the Trane brand aircon in my wife's condo.

[Carib]

Fan runs continuously in cool mode, dry mode it stops when set level is reached. I have never seen it any different on any air conditioner, that is including my own Daikin's.

Dry mode is actually a kind of a "modified" cooling mode. It has a lowered fan speed to let the moist air linger a bit longer across the evaporator unit lamellae / coil to increase maximum water extraction from the air.

On the dry setting the unit switches the fan and compressor off, to prevent moisture from the wet lamellae / coils (evaporator unit) being re-released into the to be conditioned space.

[Naam]

To Admin. You explained the difference between Dry and Cool mode very well. Simple to understand.

However, from my observations of my Daikin split-type air-conditioners, the Dry and Cool modes work the reverse of what you said i.e. in Cool mode the compressor and the fan cut out at the preset temperature; in Dry mode the compressor cuts out and the fan continues to run.

dry mode in short:

-fan is slowed down or even stopped

-compressor keeps running

-evaporator temperature drops

-lower temperature causes more condens water on evaporator fins

-lower fan speed prevents that condens water is spread again into room but drains

note:

the individual settings of manufacturers differ as far as fan speeds, cut-in/cut-out temperatures and timings are concerned. but basically they all work as described above.

any man claiming that the laws of physics do not apply when it concerns his aircon unit will be fined to promenade Walking Street in Pattaya up and down for three consecutive days wearing stiletto heels and a miniskirt.

repeated offenders will have to bear the full brunt of the laws of physics.

[Naam]

Fan runs continuously in cool mode, dry mode it stops when set level is reached. I have never seen it any different on any air conditioner, that is including my own Daikin's.

Dry mode is actually a kind of a "modified" cooling mode. It has a lowered fan speed to let the moist air linger a bit longer across the evaporator unit lamellae / coil to increase maximum water extraction from the air.

On the dry setting the unit switches the fan and compressor off, to prevent moisture from the wet lamellae / coils (evaporator unit) being re-released into the to be conditioned space.

we have a winner!

[Naam]

Most efficient of all is to switch it off. Tit get used to it ---- adapt.

most irrelevant comments come from people who enjoy sweating

[Carib]

To Admin. You explained the difference between Dry and Cool mode very well. Simple to understand.

However, from my observations of my Daikin split-type air-conditioners, the Dry and Cool modes work the reverse of what you said i.e. in Cool mode the compressor and the fan cut out at the preset temperature; in Dry mode the compressor cuts out and the fan continues to run.

dry mode in short:

-fan is slowed down or even stopped

-compressor keeps running

-evaporator temperature drops

-lower temperature causes more condens water on evaporator fins

-lower fan speed prevents that condens water is spread again into room but drains

note:

the individual settings of manufacturers differ as far as fan speeds, cut-in/cut-out temperatures and timings are concerned. but basically they all work as described above.

any man claiming that the laws of physics do not apply when it concerns his aircon unit will be fined to promenade Walking Street in Pattaya up and down for three consecutive days wearing stiletto heels and a miniskirt.

repeated offenders will have to bear the full brunt of the laws of physics.

Careful there Naam, some may even like that kind of punishment....

[Payboy]

I've found "auto" mode works like a dream.

[samran]

So basically - if I don't use aircon very much, then if I want to make my room feel a bit more comfortable with the standard fans I stick on dry mode for a bit, then turn it off lest I damage the aircon unit?

Otherwise, keep it on cool or auto.

Or move to Antarctica to please the JomBom's of the world.

[Naam]

if I want to make my room feel a bit more comfortable with the standard fans I stick on dry mode for a bit

[Pib]

On my York split A/C the manual says when setting to Dry Mode the fan is set automatically to low speed. Basically this allows the air to move slower through the evaporator (inside unit) coils/fins which allows more humidity/water to be removed before being blown into the room.

[Pib]

Here's how LG describes the Cool, Fan, and Dry Modes: Link