Sizing an Air Conditioning System

[digbeth]

3 hours ago, Encid said:

That was my original plan, however both my wife and my builder said that it is not good (according to Thai "feng shui") to have a cassette unit in the bedroom, as you cannot control the amount of air that is blowing at your face and "you can get sick".

 

Thai "feng shui" is important in building a house here... I'm not brave enough to go against the grain... we will be installing a wall mounted split system in the bedroom. 

Cleaning a cassette type in the middle of the bedroom could mean mess all over the bed as oppose only 1 wall of the room, even if it needs cleaning less often than the wall type, you wouldn't want the tech climbing over your bed to service the unit maybe

[Encid]

Just now, digbeth said:

Cleaning a cassette type in the middle of the bedroom could mean mess all over the bed as oppose only 1 wall of the room, even if it needs cleaning less often than the wall type, you wouldn't want the tech climbing over your bed to service the unit maybe

Another good point... 

[Yellowtail]

31 minutes ago, digbeth said:

Cleaning a cassette type in the middle of the bedroom could mean mess all over the bed as oppose only 1 wall of the room, even if it needs cleaning less often than the wall type, you wouldn't want the tech climbing over your bed to service the unit maybe

I clean the filters myself and I don't clime on the bed, I use a small ladder. The cassette filters (at least mine) are pleated so the surface area is much greater, and the dust does not drop off as easily. 

 

Yours is a good point if the room is very small, but it has not been an issue for me. Cleaning the filter does not seem to make a mess, and if I did drop the filter on the bed, I would just wash the bed-clothes. 

 

I just hose the filters off in the shower and put them back in. 

 

 

[lopburi3]

20 minutes ago, Yellowtail said:

I clean the filters myself and I don't clime on the bed, I use a small ladder. The cassette filters (at least mine) are pleated so the surface area is much greater, and the dust does not drop off as easily. 

 

Yours is a good point if the room is very small, but it has not been an issue for me. Cleaning the filter does not seem to make a mess, and if I did drop the filter on the bed, I would just wash the bed-clothes. 

 

I just hose the filters off in the shower and put them back in. 

 

 

But split units should have a real cleaning every 6 months to a year to remove dirt in cooling coils and that is high pressure water draining into 5 gal paint cans and then high pressure blower - so a bit of overspray - but bed can be moved and covered with water proof material.  There is a lot of dirt that gets through those filters (think teenagers).  Outside units should also be cleaned at same time.

[Yellowtail]

6 minutes ago, lopburi3 said:

But split units should have a real cleaning every 6 months to a year to remove dirt in cooling coils and that is high pressure water draining into 5 gal paint cans and then high pressure blower - so a bit of overspray - but bed can be moved and covered with water proof material.  There is a lot of dirt that gets through those filters (think teenagers).  Outside units should also be cleaned at same time.

Fifteen+ years with only filters twice a year, and once a year brush off the area around the filter and wipe the louvers off with a wet rag. 

 

With a cassette, the return air is drawn up through the filter, across and down through the coil so the coil stays much dryer, and the fan never gets wet. 

[lopburi3]

19 minutes ago, Yellowtail said:

Fifteen+ years with only filters twice a year, and once a year brush off the area around the filter and wipe the louvers off with a wet rag. 

 

With a cassette, the return air is drawn up through the filter, across and down through the coil so the coil stays much dryer, and the fan never gets wet. 

You must live in a clean room and never allow outside air in.  ???? There can be a huge amount of dirt in coils which in turn you pay for with higher operating costs.  Air conditioner normal filters are far from HEPA.

Edited March 23, 2023 by lopburi3

[Elkski]

I sizes and installed my dual Aircon heaters in an accessory apartment.  Aircon requirements were almost null because walk out basement with cooled room above.  I used LG red.  I looked into the cassette for main area but couldn't fit it in the ceiling.  I don't understand the Feng shui issue? I know stairs not supposed to head out the door or that's what will happen to your money.   Can't a cassette be placed off center and perhaps 1 vent closed?  

Heat flow is proportional to the Temp delta to the 4th power. So if course your comfort setting matters in sizing. But fan speed and temp are all controlled via remote.  And the remote can even be placed anywhere and is the thermostat. I loved having this during love making in Thailand.      This is a well built GH and shaded.  Are your various calculation all using the actual window measurements?   Sorry I don't have a good feel for mini split Aircon sizing.  But I used a 7k unit in 12sq m back bedroom mostly below ground and heated ceiling from home above.  9k in 16 SQ m room with 1 outside wall.  18k in 27k kitchen living area.  And for sure  heating Delta temps here higher than Thailands cooking.   20f outside 70 in 50 delta.  Vs 99f and 74 for 25 delta in Thailand.   

Edited March 23, 2023 by Elkski

[Encid]

I wanted to thank everybody who contributed to this topic... it has given me some good food for thought.

 

I have decided on the following units:

 

For the bedroom (21m² with 3m high ceiling): 14330 BTU Mitsubishi Electric Mr Slim Super Inverter Wall Mount model MSY-GT15VF with a SEER rating of 21.5.

https://www.mitsubishi-kyw.co.th/Product/For-Home/conditioner/GT-Series/1107.aspx?NodeID=1107&ProductType=1

 

And for the living/dining/kitchen area (36m² with 3m high ceiling): 24,225 BTU Mitsubishi Electric Mr Slim Inverter Ceiling Cassette model PLY-SM24EA-TH with a SEER rating of 23.74.

https://www.mitsubishi-kyw.co.th/Product/For-Home/conditioner/PLY-Series/4156-(1).aspx?NodeID=6507&ProductType=1

 

Those units selected should satisfy all our potential visitors and their preferred living/sleeping temperatures... from 20°C to 27°C, except for those really stinking hot days when the mercury hits 40°C or more...

[couchpotato]

24 minutes ago, Encid said:

I wanted to thank everybody who contributed to this topic... it has given me some good food for thought.

 

I have decided on the following units:

 

For the bedroom (21m² with 3m high ceiling): 14330 BTU Mitsubishi Electric Mr Slim Super Inverter Wall Mount model MSY-GT15VF with a SEER rating of 21.5.

https://www.mitsubishi-kyw.co.th/Product/For-Home/conditioner/GT-Series/1107.aspx?NodeID=1107&ProductType=1

 

And for the living/dining/kitchen area (36m² with 3m high ceiling): 24,225 BTU Mitsubishi Electric Mr Slim Inverter Ceiling Cassette model PLY-SM24EA-TH with a SEER rating of 23.74.

https://www.mitsubishi-kyw.co.th/Product/For-Home/conditioner/PLY-Series/4156-(1).aspx?NodeID=6507&ProductType=1

 

Those units selected should satisfy all our potential visitors and their preferred living/sleeping temperatures... from 20°C to 27°C, except for those really stinking hot days when the mercury hits 40°C or more...

These units are ample for your sqm. Good products also. Just be around the day the A/C techs do the installation, so you can choose the correct positions of the indoor and outdoor units.

(Plus check ample insulation required around the piping that will reside in the ceiling)