Air Conditioning Question

[CM Fred]

The house I am building has a combined sitting room and dining room, separated by a bar. This area is a total of 55 square meters. The engineer on the project at first recommended two 18,000 btu units. Now he says that only one 18,000 btu unit is required. From what I read on the forum, one unit is not nearly enough. The reason he gave for the change is that the second unit would have to be located at the front of house, and would not look good. There is also a front porch that would be impacted by having a second unit. His last recommendation was to have only one unit, but increase the size to 26,000 btu. The sizes of the air cons he recommended for the other rooms of the house generally conform to what I have seen on this forum.

My question is; is one 26,000 btu unit adequate? The longest part of the rooms, 11 meters, faces east. The five meter portion faces north. The north side of the house is where he wants to install the air con. There are also 3 large windows, 2 facing east, 1 facing north.

Thanks for any comments or recommendations.

[DrAndy]

there are several sites that can help

Air Conditioning Calculator. Calculate your air conditioning needs. PRA air conditioners provide a long service life and great value. Cheaper than fans for each worker...

in the end, it is fairly inaccurate as there are also several other factors that can influence the choice

but make sure the unit is big enough as one running a lot of the time is tedious

[Norton]

I have room similar size as yours. 3 meter ceiling. Ceilings insulated. 2 windows west exposure and one north. Using a Toshiba 23,060 btu/hr. Works fine but could be quicker at cooling room. Takes 15-20 mins to get comfortable temp. Would be better if 26,000 btu as your guy suggests.

[CM Fred]

DrAndy, Thanks for the link, it is very helpful.

Norton, Thanks, I was hoping someone on here would have a similar situation.

[ltnt]

Wouldn't air circulating fans do a better job in efficiency in time required to cool down a room? Ceiling fans?

[dirtydog]

^Blowing 30degree plus air around a room doesn't cool it down that much.

[DrAndy]

and aircons have fans that are efficient

[Albert Shagnastier]

get 2 smaller units, one at each end of the room/area and some fans to circulate the air

The reason he gave for the change is that the second unit would have to be located at the front of house, and would not look good

yeah - cos that makes sense

[Grower]

Don't forget; north in the summer is hottest because we're at about 13° N.Lat.
Shade works wonders.

[Albert Shagnastier]

And get that reflective silver plastic anti UV stuff sewn onto the back of the curtains, cuts the heat entering the room down massively.

[ltnt]

I rarely use ac. 99% of the time I use fans. The times that I do use a ac are during the evenings when it does not cool down, but only for initial cool downs.

When I first moved here I had a Thai lady tell me that it was better not to use ac and to get use to the heat index naturally. If you used a floor fan to circulate the air and the house was properly ventilated then there was no need for ac. Actually she said the ac makes you sick or more prone to sickness.

I've followed those principles for the past 10 years and its been good advice in my experience. I do understand those who use ac and their need to do so. I suppose if you live in Bangkok where it really heats up due to radiant heat and lack of air flow, pollution etc. I to would want ac full time.

[Dillinger]

My question is; is one 26,000 btu unit adequate?

I would go with ceiling fans, also you can get those nice looking portable cool air blowers for your lounge.

I don't know how much they are to run

[Thetyim]

^
How is the air cooled or is it just a blower ?

[DrAndy]

north in the summer is hottest because we're at about 13° N.Lat.

I have no idea what you mean, do you?

[DrAndy]

When I first moved here I had a Thai lady tell me that it was better not to use ac and to get use to the heat index naturally.

agreed except when you are trying to get some sleep on those hot humid nights

In the daytime, I haven't seen the need for aircon at all

[Humbert]

A 26,000 btu split type unit should work fine for that size room. I think the AC should be mid point of the long wall if possible so the unit doesn't have to blow air all the way down the length of the room.

[DrAndy]

The house I am building has a combined sitting room and dining room, separated by a bar.

whilst rooms like that are very nice, have you thought that you could eat and drink in a charming outside space? then aircon would be redundant (as would those western style rooms)?

the tropics are not the same as the temperate regions, and life can be lived in a different manner

[hillbilly]

This is my experience with air conditioners. I am no expert by any means and often get confused by BTUs and square footage.

The 26,000 BTU would be a good choice. Keep in mind that you could get two smaller ones but the upkeep for both is double.

Within reason, the bigger the bang seems to work and save money in the long run. However, some people disagree with this theory.

The hillbilly enterprise (555) is responsible for 19 AC units. Once again while not an expert on air conditioning I have learned by experience.

[dirtydog]

I would go with ceiling fans,

Good for you, but if you read his post he wants air-con, did you know there is a major difference between the two?

[Dillinger]

^Just my opinion. I dont have aircon in my living room. how long is a piece of string ?

My question is; is one 26,000 btu unit adequate? The longest part of the rooms, 11 meters, faces east. The five meter portion faces north. The north side of the house is where he wants to install the air con. There are also 3 large windows, 2 facing east, 1 facing north.

Errrmmmm......... Do you have a calculator ?







1
Take the floor measurements of each of the rooms that you expect to cool with the air conditioner. The height does not matter too much since the cool air sinks. Multiply the width by the length and then add them all together. This is the square footage, and since there are 337 BTUs per square foot, multiply them by 337. Write this figure down.

2
Measure each of your south side windows and figure the square footage of each (width times height). Add the square footage up and multiply it by 871 BTUs. Do the same for the north-facing windows and multiply the square footage by 166. Add these two figures together and write it down.




3
Count how many people you expect to be living in the area to be cooled. Each person will generate about 400 BTUs each, so multiply the number of people by 400. Write this figure down.

4
Walk around and look at your lights. Write down the number of watts per light and multiply it by 4.25 BTUs. For instance, a 100 watt bulb would generate 425 BTUs. If you have 10 lights, you would have 4,250 BTUs of energy being given off. Add all the amounts together and write the sum down.

5
Check to see if you have any appliances or machines that will be running in the area to be air conditioned. See what the maximum wattage is for the appliance and then multiply it by 3.15. This is the maximum usage, and although you might not always run it at full capacity, it is better to have an air conditioner unit that can handle more rather than less than you need. Write this appliance BTUs figure down.

6
Add up all the BTUs for each of the 5 Steps. This is the total BTUs you will need your air conditioner to be able to handle. When you go to shop for an air conditioner, it will need to be big enough to do at least this amount of cooling.

[BallBreaker]

I live in a 2 bedroom condo on a middle floor that is 116 sqm's total. My sitting/dining room is 38 sqm's and is cooled by 18,000 BTU Daikin unit. It keeps room cool during March/April despite having 4 meters of sliding glass doors facing west without any problems. I have also found during heavy rain periods like last couple weeks I can use it in dry mode (dehumidify) and keep the entire living space comfortable (60% Humidity) without running other room units.

[ltnt]

6 Add up all the BTUs for each of the 5 Steps. This is the total BTUs you will need your air conditioner to be able to handle. When you go to shop for an air conditioner, it will need to be big enough to do at least this amount of cooling.

Do you do wiring as well? When I start my electrical installation are you available for consultation? Fee's to be negotiated.

[CM Fred]

The house I am building has a combined sitting room and dining room, separated by a bar.

whilst rooms like that are very nice, have you thought that you could eat and drink in a charming outside space? then aircon would be redundant (as would those western style rooms)?

the tropics are not the same as the temperate regions, and life can be lived in a different manner

As a matter of fact, I will have an outside space, 3 x 3 meter to do just as you suggested. I hope that it does turn out charming. I also have a front porch that will extend along the entire front of the house, and will connect with the other porch. The front porch will hopefully also be used for socializing. It is really not the best configuration to have the a/c compressor right in the middle of that. Additionally, I agree with the engineer that it would not really enhance the looks of the home.

The sitting room turned out as large as it is because it was either that or have another bedroom I don't need. I opted for the larger sitting room, and have it combined with the dining room to have a more open feel. It is probably not the best designed house, I designed it myself. I made minor changes to conform to certain realities.

Once I learn to post pictures, I will try to add some on here.

Thanks for all the replies, I found them all beneficial.

[ltnt]

It is really not the best configuration to have the a/c compressor right in the middle of that.

Have you thought of elevating it? Mount on the wall as high as you can, (out of the way, no head knocker) utilize a metal frame support and dowel into the wall. I have one done in this manner, but its on the second floor of the house. Works great and no corrosion problems with the metal frame in 8 years.

[ralphlsasser]

Need more information. 1) how many outside doors and windows in the space? 2) what type? In a perfect world, for 55 sq meters or around 165 sq. ft, you'd need about 25,000 btu's of cooling. But TIT and materials aren't made with energy saving in mind, so if I was bidding the job, not knowing the type and quanity of outside windows and doors, I would bid it figuring a total btu output of 30,000. It's better to have a little more than a little less cooling btu's to make up for the non energy saving windows and doors. I was a licensed a/c contractor for 27 years and never had a problem with the units I installed not being enough to do the job. I can give you a more accurate estimate of the needed BTU's if you can answer the questions. That can made a big difference in what's needed. I hope this helps.