Air Conditioner Size

[KannikaP]

Just about to fit ACs in girl's bedroom 4 x 4 x 2.2 metres  high. Only sunny in the morning and will have ceiling insulation after fitting.

Been on several 'calculator' sites which some suggest 9000BTU and others 12000.

I have had Mitsubishi Mr Slims for 10 years trouble free, so would go for that make, but there are so many different models, MS-GN09VF, KT-09VF and now Happy Inverter is only Bht 11800 from Lazada. 

Can anyone suggest the correct size and model please.

Been quoted Bht 3000 for fitting.

Edited October 31, 2021 by metisdead
ALL CAPS removed from topic title.

[Crossy]

Yeah, 9,000 to 12,000 BTU would be the standard Thai guesstimate.

 

With a well insulated bedroom then towards the low end would be just fine.

 

I would go inverter or the (relatively small) energy savings.

[ourdon]

Agree with Crossy.  The 9000 will work well and you have a manufacturer that you like already..

 

Are you sure about the 2.2 height?  Just strikes me as a little low

[KannikaP]

12 minutes ago, ourdon said:

Agree with Crossy.  The 9000 will work well and you have a manufacturer that you like already..

 

Are you sure about the 2.2 height?  Just strikes me as a little low

Well spotted, 2.8 metres high ceiling, so maybe go for 12000.

[Kwasaki]

17 minutes ago, KannikaP said:

Well spotted, 2.8 metres high ceiling, so maybe go for 12000.

Either 9 - 12 will do if it's well insulated room inverter type will do.

Bought from local places like Global house 500 baht for ground or 1st floor fitting or reasonable installing access.

[lopburi3]

9K model should be more than enough - unless you want meat locker temps (which understand some do).  But for about 26c have had no issues using 9k in my bedroom of 26 sm for last decade which is not well insulated but direct sun on roof only a few hours per day and live in room most of the time.

[dddave]

Take note that with Mitsubishi, there are 2 separate entities selling AC units:  "Mitsubishi Electric" & "Mitsubishi Heavy Industries"    The attached article explains it better than I can.

 

 https://www.smarterair.com.au/mitsubishi-heavy-industries-vs-mitsubishi-electric/#:~:text=A Bit about the Two,both companies produce quality products.

[bankruatsteve]

With an inverter unit, you will probably be running at 4k most of the time anyway - no matter what size maximum.

[KannikaP]

16 minutes ago, bankruatsteve said:

With an inverter unit, you will probably be running at 4k most of the time anyway - no matter what size maximum.

4k ????

[ourdon]

57 minutes ago, KannikaP said:

Well spotted, 2.8 metres high ceiling, so maybe go for 12000.

Prudent, a little bit of excess capacity isn't a bad thing.   A bigger unit does not necessarily mean meat locker temps.  A setting of 26c is still 26c no matter how big the unit is.  Within limits it just means shorter run times.

 

Take Care

[bankruatsteve]

4 minutes ago, KannikaP said:

4k ????

4k BTU.  That's just using my 11kBTU Daikin as example.  Once it reaches temperature, it throttles down to a few hundred watts.

 

Specs on the unit should show the operating range.  Generally sold at the maximum (12k BTU) but also has minimum which the dry setting usually operates at.  My Daikin ranges from 11k to 2k.

Edited October 31, 2021 by bankruatsteve

[KhunLA]

"Happy Inverter is only Bht 11800 from Lazada."

 

seems like a winner.  Without knowing the construction / insulation rating, hard to recommend.  I undersized my last house, although well built, insulated, shaded & Q block used.  At worse, I'd simply have to add another unit, which I didn't.   Did the same for current build, again, same building specs, very good all around.

 

Since you're doing 1 room, I'd go bigger, instead of the 9k BTU.  If a larger area, you would have more room for error, and adjust with adding another unit. 

[lopburi3]

1 hour ago, ourdon said:

Prudent, a little bit of excess capacity isn't a bad thing. 

Actually it is a very bad thing as much better to have proper dehumidification that a properly sized unit provides (and this is especially true in a tropical rain country),.

[bankruatsteve]

1 minute ago, lopburi3 said:

Actually it is a very bad thing as much better to have proper dehumidification that a properly sized unit provides (and this is especially true in a tropical rain country),.

True with non-inverter but the inverters will continue dehumidification even though operating at a fraction of maximum capacity.

[lopburi3]

2 minutes ago, bankruatsteve said:

True with non-inverter but the inverters will continue dehumidification even though operating at a fraction of maximum capacity.

Yes but many are still operating at too high at min output if bought oversized.  

[bankruatsteve]

4 minutes ago, lopburi3 said:

Yes but many are still operating at too high at min output if bought oversized.  

I didn't think so, but there you go.

[Kwasaki]

4 hours ago, lopburi3 said:

Yes but many are still operating at too high at min output if bought oversized.  

There's calculations for Inverter type Air-cons, I  bought a cooler unit 18 BTU and my bills when down we have a 9 BTU before. 

 

Our bedroom wouldn't benefit from an inverter unit, and the extra cost them wasn't justified. 

 

Another will be when the inverter units go wrong depends where you live on finding someone who can fix it. 

[Young Mutley]

Hi Team, can I jump on this thread and pick your brains re what size a/c unit I need. Just built an extension to our house in Udon - 32 sqm room (in shade for much of the day). Checked various calculators and get various estimates - from 15,000 btu to 28,000btu. 
Had a local company come to look at the exterior, they reckon I need 36,000 btu at a cost of 54,000THB.

Any advice?

[bankruatsteve]

Unless your insulation is poor or you need arctic weather, a 12k BTU inverter will be just fine.

 

Most calculators are for old style AC and always at the high end.

 

Edited December 27, 2021 by bankruatsteve

[lopburi3]

That is a fairly large room - as said how many windows/insulation and how cold you need it can makes a huge difference.  Being in Udorn (I still spell it 1960's) and home expect you will not need too much cooling so 12k may indeed be enough - you can always install another if one is not enough and then have backup if one fails.  But suspect I would go 15k myself as price not that much more and inverter is best when not full out.    

[sometimewoodworker]

11 minutes ago, bankruatsteve said:

Unless your insulation is poor or you need arctic weather, a 12k BTU inverter will be just fine.

Absolutely, though as long as you get an inverter you could jump it up to 15,000 or even 18,000 without a problem.
 

If going for a conventional (non-inverter) you absolutely do not want to oversize and the 12k unit is the one to go for.

 

16 minutes ago, Young Mutley said:

Just built an extension to our house in Udon - 32 sqm room (in shade for much of the day). Checked various calculators and get various estimates - from 15,000 btu to 28,000btu. 
Had a local company come to look at the exterior, they reckon I need 36,000 btu at a cost of 54,000THB.

Just for reference our 85 sqm room that has between 3.8m and 6m ceilings has a 36k unit and as you can see I’m in the same general area as you

[Young Mutley]

Thanks for the feedback guys - picture of room attached. Getting lots of conflicting advice from friends. Some say that 36 BTU is necessary, while others say that half that will do the trick ???? Been quoted 54,000 THB for a 36,000 BTU Carrier model.

[Crossy]

32m² would guestimate out at 19,000 to 22,500 BTU, I'd be edging towards the high end or even a bit more coz you have lots of glass (is it double glazed?).

 

It might be worth going for two smaller units so you could run only one during the cooler season.

 

[lopburi3]

As said probably best to mount a 12k unit at each end as suspect that glass will be single pane but much of the time probably only need to run one system.  

[bankruatsteve]

4 minutes ago, lopburi3 said:

As said probably best to mount a 12k unit at each end as suspect that glass will be single pane but much of the time probably only need to run one system.  

Yep.  I would also drop a ceiling fan in the middle of the lights to distribute air when only one unit is running.  If those windows get direct light at all, you will want drapes.

[sometimewoodworker]

2 hours ago, Crossy said:

32m² would guestimate out at 19,000 to 22,500 BTU, I'd be edging towards the high end or even a bit more coz you have lots of glass (is it double glazed?).

 

It might be worth going for two smaller units so you could run only one during the cooler season.

 

I would virtually guarantee that it’s not double glazed and probably not low-E glass either.

[Kwasaki]

3 hours ago, Crossy said:

32m² would guestimate out at 19,000 to 22,500 BTU, I'd be edging towards the high end or even a bit more coz you have lots of glass (is it double glazed?).

 

It might be worth going for two smaller units so you could run only one during the cooler season.

 

5m x 6m room 30 m2  9btu if it has glass all around and u insulated wall and ceiling 18 BTU.