Air-con Sizing?

[Naam]

Technocracy, I'll email a mate of my'n in Oz & hopefully he will send me some a/c survey documents, then we can all move away from speculation.

the problem remains that any Oz survey documents do not take a home in Laos and the demands of its inhabitants into consideration. i'm also sure that "Techno" cannot provide exact r-values of his outside walls and ceiling insulation. we (and that includes me) should try not to complicate the matter beyond a certain extent.

[elkangorito]

Technocracy, I'll email a mate of my'n in Oz & hopefully he will send me some a/c survey documents, then we can all move away from speculation.

the problem remains that any Oz survey documents do not take a home in Laos and the demands of its inhabitants into consideration. i'm also sure that "Techno" cannot provide exact r-values of his outside walls and ceiling insulation. we (and that includes me) should try not to complicate the matter beyond a certain extent.

In actual fact, half of Australias climate is exactly like Loas, Thailand etc. It is tropical.

It will not be a difficult thing to 'normalise' the survey to suit a tropical climate. Most surveys do not require 'R' values of insulation as they are always a slight overestimate anyway.

[Naam]

700-800 BTU/Hr/m2 is a good estimate.

if that rule applies then my home (480m² living area) would need 336.000 btu/h even taken the lower value of 700. i have a total of 190.000 btu/h installed and never used more than 65.000 btu/h to cool it down to 26-27ºC, i.e. even 700 is way off the mark.

by comparison: my last home in Florida (450m² living area) with hot and humid summers as in Thailand had three central a/c units (total 96.000 btu/h) , we had the thermostats set at 25ºC and achieved this temperature without any problems throughout (when there was no power cut ).

[Naam]

In actual fact, half of Australias climate is exactly like Loas, Thailand etc. It is tropical.

i am well aware of that. about a decade ago we bought a plot up in the hills overlooking Mooloolaba, Queensland and consulted several builders in that area. to our surprise aussie builders knew their job as far as insulation and saving of energy was concerned. in fact aussie builders impressed us in each and everything in a quite positive way except... that they could not understand why a big home of >400m² should have more than two bathrooms.

quote: "yer can't be sihttin' all the time mate!"

are you trying to tell me that lao builders can match the proficiency of aussie builders?

[quiksilva]

I for one look forward to seeing these revised a/c survey documents.

A practical guide for selecting a/c units which is more accurate than the 700-800 BTU/sqm/hr I was told about would be truly appreciated as I am about to buy 3-4 units over the next month.

Failing that I may have to extend that offer of wine too!

[Naam]

I for one look forward to seeing these revised a/c survey documents.

A practical guide for selecting a/c units which is more accurate than the 700-800 BTU/sqm/hr I was told about would be truly appreciated as I am about to buy 3-4 units over the next month.

Failing that I may have to extend that offer of wine too!

any time!

[ThailandTony]

There is no substitute for experience and ours (The good doctors and mine) sounds like reasonable & practical advice. Those BTU calculators are way off, and as we said, you only need the full capacity of the units for a 2 month period in April/May. Sound advice also on good insulating techniques Doc!

[Naam]

Sound advice also on good insulating techniques Doc!

i have also acquired some proficiency how to empty sherry and portwine bottles and i'm able to give sound advice in this respect on demand.

[Khonwan]

-in the case of the OP seeking advice TWO units (albeit more expensive initially) are the solution. the units should be placed in a 90º angle.

Why at 90 degrees? Were they fans, they should be placed in line, e.g. one could be placed above the archway with the other at the rear of the adjoining room (so that both are facing the same direction). Why should this not also apply to A/C units?

[technocracy]

Technocracy, I'll email a mate of my'n in Oz & hopefully he will send me some a/c survey documents, then we can all move away from speculation.

the problem remains that any Oz survey documents do not take a home in Laos and the demands of its inhabitants into consideration. i'm also sure that "Techno" cannot provide exact r-values of his outside walls and ceiling insulation. we (and that includes me) should try not to complicate the matter beyond a certain extent.

You never asked you were too busy trying to prove you knew the most without actually helping.

Just so you know the 50% the walls have an R-Value of 1.2 and the other 50% are 2.0. The ceiling insulation will be have a value of R-10 and also have a radiant barrier.

But I found the details calculation I was after which I will do tomorrow - been bit to busy overseeing the work the past few days to reply.

elkangorito - cheers for the offer but I've found what I was after now.

[quiksilva]

Any chance of sharing link to the info?

[elkangorito]

I have attached an airconditioning survey (sizing) form, which is used in Australia. Please assume an ambient temperature of 35 degrees Celsius.

[backflip]

www.energystar.gov

[technocracy]

I had forgot about this thread!

For me I have actually acquired a copy of RHVAC which performs a full Manual J calculation complete with climate weighting (i.e. you can set your location) and your desired temperature - amongst many many many different variable

The total calculations for the for which I was after came out at 24000btu for the joined room and 15000btu in the bedroom.

So the site I previous mentioned was spot on for the bedroom but out for the downstairs. So basically I will be buying a 17000btu (5Kw) for the bedroom and a (7Kw) for the Living area. But to allow for more people (parties, blessings etc) there will be a secondary 11000btu (3.2Kw) unit for to give that extra cooling ability.

Oh in regards to the design of the house (by myself) and the construction materials - basically the roof is as cooling friendly as possible. First of there is the CPAC padded radiant (which after looking at similar materials in homepro I'd estimate has a R value between of R13 and R15) then the ceiling is lined with a glass fibre layer just to put the layer on the cake the roof space is cooled by a 14" Whirly bird plus has vents on under eves to assist in changing the air. So I'd say it's pretty much as good as would be required.