One or two aircons?

[TheMysteriousMrTesla]

We have a long relatively narrow lounge, about 9m by 4m so 36m².

 

Currently it doesn't have any A/C and with plenty of through ventilation it's quite comfortable for me with just fans. It only gets sun through the windows early and late, the windows are well shaded during most of the day.

 

We have family coming from the UK early next year so I think adding aircon to this room will make them more comfortable when watching the telly.

 

Conventional Thai wisdom of 6-700 BTU per m² gives us 21,000 - 25,000 BTU required.

 

So, considering the shape of the lounge would having one large unit or two smaller ones be the way to go?

 

[simoh1490]

If it was me and with a 9m long room, I'd try and put one unit at either end and split the load (but with some overlap of course), 

[ArickChaiyaphum]

I have 50sqm open plan with 11,800 BTU invertor and 1 fan and that is fine. Even when it was 40c. Be careful of some Samsung models because ghekos short out the chip boards. I replaced one of mine last month with a Daikin invertor much smaller extractor outside then the Samsung but funny enough 11,000 BTU I have it in 20sqm bedroom and set at 27c works great 

[TheMysteriousMrTesla]

Thanks so far chaps.

 

We are limited as to where we can put the indoor units there's space about 6m along one long wall and again at maybe 2m of the same wall. the end walls are non-starters.

 

Also there's only space for one outdoor unit on the ledge constructed for same so we would need a stacking arrangement for two units.

 

My current thinking is two non-inverter units, our power can be a little "lumpy" so I'd like to keep things simple. We could run one unit alone in the cooler weather, also we get some redundancy if there's a failure.

 

[bankruatsteve]

FWI:  I cool a 3.5 x 10 meter living area indirectly through my bedroom (leaving the door and shutters open).  This is with a 12K Daikin.  With ceiling fans to move the air it is very comfortable even when HOT.

[Issanman]

I have a Panasonic 18K inverter cooling a 56sqm room and it works just fine.

None of the walls of this room are exposed to direct sunlight, however.

[KittenKong]

12 minutes ago, Issanman said:

I have a Panasonic 18K inverter cooling a 56sqm room and it works just fine.

None of the walls of this room are exposed to direct sunlight, however.

I have a slightly larger Hitachi inverter in a very slightly smaller area and that also works fine. One entire wall is glass and gets a little direct sun at some times of day.

I suppose my set up might struggle if I wanted the room at 19 degrees, but I have it set constantly at 27, with one ceiling fan on slow, and it's all good.

 

I would never buy another aircon that was not an inverter.

[stevkob]

Generally speaking an 18k btu (5kw) inverter wall hung split system should be adequate.

I would consider the installation placement if I were you, it would be preferable to install the indoor on an exterior wall in a back to back configuration with the outdoor condensing unit.

Installation can rack up the purchase price if you have long internal and external runs, I would not recommend installing the indoor unit on an internal wall for various reasons.

 

[sometimewoodworker]

2 hours ago, TheMysteriousMrTesla said:

Conventional Thai wisdom of 6-700 BTU per m² gives us 21,000 - 25,000 BTU required.

I have found that 500 BTU per m2 is plenty, I also prefer AC + fan as then you can be comfortable with a higher room temperature and not have such a large temperature differential to the outside.

 

so what I would do is put in 1 AC of maybe 12,000 BTU. That lets you decide if it's enough and if not add a second.

 

Do not forget that oversized AC is much worse than correctly sized or even slightly undersized ones because an oversized AC will not be able to reduce the humidity anywhere nearly as well as a smaller unit and it's the Thai humidity that makes new arrivals uncomfortable.

[Tracyb]

I recommend you check out Daikin Inverter models.  They tolerate variances in power supply voltage.  You’ll also find that they operate within a range of BTU’s for each unit.  One unit, 18k, which will run at a range of between, approx., 15 to 17 btu, mounted as close as possible to the outdoor unit to avoid costs for extra refrigerant lines should work just fine.  You can check the models out on the Daikin website to see the operating ranges, power consumption, etc.  These units come with 5 meters of piping at no extra cost.  I use a Daikin “Smart” unit in a similar sized room with excellent results.  The “Smart” unit allows you the option to activate motion detection in the room to allow the temperature to increase by 2’C when no one is there.  It’s an optional feature that you can switch off and on via the remote so you can have the a/c running even if no one is in the room.I’m very happy with the Daikin inverter type units.  They consume a LOT less power and they do a great job.  Oh, and Daikin focuses on making a/c units unlike Samsung, Mitsubishi and others who have their hands in many other technologies.  Okay.  That’s my 2 cents!

 

Edited November 5, 2018 by Tracyb

[1337markus]

3 hours ago, simoh1490 said:

If it was me and with a 9m long room, I'd try and put one unit at either end and split the load (but with some overlap of course), 

Also allows if one of them fails you have a back up A/C, we have done that for our bedroom.

[Estrada]

Suggest you install two aircons. I also have a long room 9m x 4m. Originally the supplier installed one large 18,000Btu/hr Air Con at one end of the room and it was difficult to keep the far end of the room cool, whilst the end with the air con was too cold. My monthly bill, which included 3 other air cons in the bedrooms was B8,000+. I replace this aircon with two 13,000Btu/hr aircons at opposite ends of the room lounge end and the other working office end. This mean that I only need to run one air con during the day at the office end and the other when watching TV. The result has been a B3,000 reduction in my monthly bill down to B4-5,000/month for the whole house.

[Catoni]

2 hours ago, bankruatsteve said:

FWI:  I cool a 3.5 x 10 meter living area indirectly through my bedroom (leaving the door and shutters open).  This is with a 12K Daikin.  With ceiling fans to move the air it is very comfortable even when HOT.

   Same with me.....   That's all I use when in Thailand and Cambodia.   Windows open in my apartment, and fans on..   I never even turn the A/C on...   never use it.   

   Oh...wait.. the 12k Daikin is an A/C unit you have turned on ? ? 

Edited November 5, 2018 by Catoni
correction

[eyecatcher]

Seems a big expense for the sake of a few guest needing to watch the tv.

Lose the tv and encourahe outdoor sitting.

The weather is perfect for outdoor living, I havr not sat inside my house for three years! 

 

However, I agree with Stww and would go for one unit and see how it performs.

 

[Pilotman]

I have quite large open lounge area, maybe half as big again as your area OP, it has two air-cons fitted both inverters, one of 12,000 and the other of 8,000.  I never need the two on at the same time.  The 12,000 is more than adequate to cool the room sufficiently.  I never did take heed of the recommended size of air-cons , as they are inevitably overblown by many BTU and seem to want to turn the tropics into the arctic, at great expense. As an aside, my UK visitors seem very happy just to have air con in the early evening and to sleep. 

[Pilotman]

2 minutes ago, eyecatcher said:

Seems a big expense for the sake of a few guest needing to watch the tv.

Lose the tv and encourahe outdoor sitting.

The weather is perfect for outdoor living, I havr not sat inside my house for three years! 

 

However, I agree with Stww and would go for one unit and see how it performs.

 

Won't the lady of the house let you in?  Been there mate  !! ???? 

[bankruatsteve]

16 minutes ago, Catoni said:

   Same with me.....   That's all I use when in Thailand and Cambodia.   Windows open in my apartment, and fans on..   I never even turn the A/C on...   never use it.   

   Oh...wait.. the 12k Daikin is an A/C unit you have turned on ? ? 

Yah, 12K BTU Daikin "inverter" set to 25C.  My house is very well insulated and just a couple hours of morning sun on that room.  I usually don't even turn on the AC until about 10am, if then.

[TheMysteriousMrTesla]

7 minutes ago, Pilotman said:

As an aside, my UK visitors seem very happy just to have air con in the early evening and to sleep. 

Yeah, I think that this is going to be the operation mode, we have a large shaded outdoor area and they ought to be doing tourist stuff during the day anyway.

 

Unfortunately, once it gets dark the mozzies are out in force so the lounge needs to be closed up after being open all day so we need something to keep the temperature sensible (26-28C).

 

I'm tending towards something around 18,000 BTU possibly inverter towards the TV end. Fans can move the cold air around if needed.

 

[MarleyMarl]

My lounge room is about 5m wide by 8m deep and i've just got an 18k BTU Samsung unit and it works well.

 

But it is well insulated as it has a floor above, below and townhouses on each side. When installing PowerBuy made me sign a document stating that if it's not cool enough I cannot return it as the BTU math didn't work out for them lol.

[stevkob]

13 minutes ago, MarleyMarl said:

My lounge room is about 5m wide by 8m deep and i've just got an 18k BTU Samsung unit and it works well.

 

But it is well insulated as it has a floor above, below and townhouses on each side. When installing PowerBuy made me sign a document stating that if it's not cool enough I cannot return it as the BTU math didn't work out for them lol.

 

Interesting. I wonder why their heat load calcs didn't work out. Possibly it is requested for all their installs to avoid having to legally accept returns or upgrades. A 40sqm room is adequately served by a 5kw (18k btu) unit. Most likely they were concerned about the throw from the indoor unit not reaching the farthest area of the room.

 

 

[Rawairat]

All I can add is don't listen to the Daikin shop salesman, we put 2 x 24000 split ceiling units in our L shaped lounge, roughly 68m2 on his advice and one unit keeps the whole area cool in the hottest months. The formula he used must have been around 700BTU per m2. I guess we have a backup which we have not needed in 7 years.

I see there is supposedly a 30-40% saving when I googled Inverter airconditioners, is it worth replacing my older airconditioners? Anyone experience a worthwhile saving doing this?

[Oztruckie]

Maybe an option is to install one large capacity evaporate with 2 smaller size outdoor compressor units, when cooling requirements are low only 1 compressor will run, an obviously when cooling requirements are high both compressors will run, I know these units are available in Oz in the Daikin brand, maybe not available here, any half decent air con shop would or should know of there availability. 

[khunPer]

7 hours ago, TheMysteriousMrTesla said:

So, considering the shape of the lounge would having one large unit or two smaller ones be the way to go?

I would install two smaller, about half sized, units if it was my lounge...????

[eyecatcher]

Calculating the unit size is a little bit more detailed than just 600btu/m2

I am a tad more analytical with it, so that a top floor room needs lets say 300 extra to a gf. Then you can make a similar deduction if you have adjoining neighbours each side, then add for south facing windows. Then there is ceiling height which affects the volume, 3m is a standard but if you have 4m to cool its another add......

Do you have roof insulation.....

 

So yes rounded up 600/700btu/m2 may be the working average. but if you live in a greenhouse thats not going to work

Edited November 5, 2018 by eyecatcher

[KittenKong]

1 hour ago, stevkob said:

I wonder why their heat load calcs didn't work out.

Shops here assume that you want icicles forming inside your living room. So they calculate accordingly. They said that my air-con was underpowered also and they were completely wrong for my needs.

[KittenKong]

1 hour ago, Rawairat said:

I see there is supposedly a 30-40% saving when I googled Inverter airconditioners, is it worth replacing my older airconditioners? Anyone experience a worthwhile saving doing this?

I switched to an inverter and my saving was well over 50% on the total bill. Not sure how much was to do with the inverter and how much because the old air-con was very old.

 

How old are your existing air-cons?

[rickudon]

Agree that most salesmen oversize your needs. I have a poorly insulated, west facing bedroom/lounge of about 24 sq. metres. Only ever have air on afternoons and evenings, and nights except cold season.  One aircon enough, 11,000 BTU and set at 27 degrees C.

 

No mass deaths in UK's heat wave this summer, which i was present for and it was uncomfortable at night without a fan. So no need to spoil the guests. I'm sure they would be happy for one reasonable aircon in the lounge and some fans to mix it up if needed. Sleeping more of an issue.

[Wirejerker]

If you got room above your ceiling you might check out putting a cassette AC in the center of your ceiling that will give you a better distribution of air about the room


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[BTB1977]

Get them a hotel room. Cheaper than an ac unit. 

[CGW]

6 hours ago, sometimewoodworker said:

so what I would do is put in 1 AC of maybe 12,000 BTU. That lets you decide if it's enough and if not add a second.

My thoughts also, more or less what we have done with a secondary living room, keeps the humidity down and with a fan more than comfortable.