Another Aircon Question - Advice Please

[ThaiLife]

I'm looking to install an air conditioner unit into a small ground floor bungalow bedroom , I'm trying to work out the correct size of BTU's required for the bedroom area .

The bedroom has one double bed , one large double wardrobe and a desk that has one PC on it , giving off some heat , the room has 2 windows that are not in direct sun light and have little air flow from out side, so the room can get very warm . No ceiling fan, two people sleeping in the room night time , one person using the computer during the day time.

The air con unit would be used mainly during the daytime when hot /evening / night sleeping time, a comfortable temperature range of 26ºC / 28 ºC would be nice .

As for the the position of the aircon blower unit , mounted through the exterior wall , the options are show with by Green box on my diagram , I'm not sure about having the aircon blower unit mounted directly over the rear of double bed ( C ) .

My house electrical circuit breaker box is full and has no spare breakers , so I'm wondering what sort of electrical switch / box/ outlet ampere size would be required .

Another thought is , would the extra cost of an '' inverter '' type unit be justified for a small bedroom , and is the installation of an inverter unit , much difference to a conventional unit ?

Ive used a simple on line BTU calculator which recommends - 18,000 Btu , but as I know that getting the BTU size right is critical , as this is the first air con ive had fitted , can any one please comment on the above . I really need to get my air con facts right before I travel to the nearest decent main air con sales outlet ( 140km round trip ) .

[lopburi3]

Do you have insulation above room? Is roof in direct sun or has some shade from trees or other buildings?

I have a larger bedroom (about 25sm) on ground floor with basic fiberglass in roof area but no direct sun in windows and only need 9,000 btu to keep comfortable 27/29 temperature even this year in Bangkok. I have a second 15,000 btu unit that originally used as standby but is not needed for normal use - but suspect if doing physical work would want cooler.

You probably can not locate ac at actual window so I would go with your A location on door side of window. That provides best room coverage without blowing on bed at night, although you could do so.

[ThaiLife]

Do you have insulation above room? Is roof in direct sun or has some shade from trees or other buildings?

I have a larger bedroom (about 25sm) on ground floor with basic fiberglass in roof area but no direct sun in windows and only need 9,000 btu to keep comfortable 27/29 temperature even this year in Bangkok. I have a second 15,000 btu unit that originally used as standby but is not needed for normal use - but suspect if doing physical work would want cooler.

You probably can not locate ac at actual window so I would go with your A location on door side of window. That provides best room coverage without blowing on bed at night, although you could do so.

The ceiling is plaster board with no insulation above and the house roof is in constant direct sunlight , no shade.

Above both the 2 windows there's about 1mt empty wall space, between the top of the window and the ceiling

[Crossy]

The standard Thai guesstimate is 600-700 BTU per m² which gives us 12,000 - 14,000 BTU.

Since you're likely not going to be stressing the beast with your required room temperature an inverter should give some power savings.

That's going to draw about 1,400 Watts, wire it in 2.5mm² cable on a 20A breaker. You can get small boxes to house extra breakers and sit it next to your existing box.

[IMHO]

Given the heat sources you're describing in the room, and that it will be run during the day, the normal "bedroom" sizing recommendations should not be used. Based on your description, I would say adding 200-300 BTU/sqm to the normal recommendations is what you'd need to do the job.

At the highest end of that scale, that means 1000 BTU/sqm, which equates to 18,500 BTU. At the lowest end that's 800 BTU/sqm which equals 14800 BTU. Based on standard sizes, they both end up suggesting an 18,000 BTU unit.

As you will be running it during the day and at night, an inverter system should indeed save you money in the long run.he bed

Locations A and C seems to be the ones that would have the best chance of more evenly distributing air around the room. Location C would afford you the ability to direct the vents directly down at the bed, which will in turn allow you to increase the preset temperature 1 or 2 degrees at night for further energy savings while you sleep.

Edited May 7, 2016 by IMHO

[lopburi3]

Really not good to have AC above bed - they will at some point be a source of leaking water - as you have room above window believe your original A position would be best. Would highly recommend installing insulation above your ceiling - expect they can easily pull roof tiles and replace to install so should not be that expensive. I would do entire house.

As you do not require 'hotel' freezer temperatures believe 12k normal unit would work but if you can afford 15k inverter that might be more pleasant as they keep temperature very even and have more reserve if you want cooler - should be cost effective as being operated 24 hours (or almost) every day.

[ThaiLife]

Thanks to every one for your input , some good advice and ideas , I'm making a trip next week to do the rounds of large air conditioner shops and I will post back how I get on.

I did pop to our local village small air conditioner shop and they did not have any Inverter models , only the following ( some were in stock some had to be ordered )



Central Air - 16,000 BTU = 18,600 Baht
Panasonic - 12,000 BTU = 12,990 Bhat
Panasonic - 18,000 BTU = 25,800 Bhat
Haier - 18,000 BTU = 23,900 Baht
Haier - 13,000 BTU = 10,800 Baht
Electrolux - 18,480 BTU = 27,900 Baht
Sharp - 12,000 BTU = 19,900 Baht
Carrier - 17,000 BTU = 18,500 Baht
LG - 12,000 BTU = 12,500 Baht
LG - 9,000 BTU = 9,600 Baht
York - 12,900 BTU = 12,700 Baht


most with a 5 year motor warranty

Installation free , but I think the power outlet has to be all ready in place.

Looking at the condition of the shop and the battered old pick up , confidence would be lacking .

[lopburi3]

Shop condition really has nothing to do with how well they install or maintain - the units themselves should be the same wherever you buy. Smaller shops often can provide at a better price.

I have two 9k Panasonics and very happy with them. Have had LG, Central, Saijo Denki and York but would stick to Panasonic and Mitsubishi now.

[sipi]

I am a fridgy by trade and have never had a problem or been ripped of by Thai fitters. They do it every day of the week. It is good to be forearmed but from my experience they know what they are doing and can be trusted.

[Gonsalviz]

Any cement walls with direct sun are tremendous heat sinks that tend heat the room and take forever to cool down.

[bankruatsteve]

Any cement walls with direct sun are tremendous heat sinks that tend heat the room and take forever to cool down.

Well, not "any". I (and lot's of TV folks also) have "super block" (aerated cement) type of wall and there is no issue with heat sink. Most of my rooms will get hot simply from the ambient temperature eventually creeping in through open windows, doors, etc. But never from the walls.

[Burl Ives]

Try this Aussie calculator, assuming you live in Darwin, similar climate to here, but fill it in honestly, with real measurements:

http://www.fairair.com.au/calculator.size.aspx

[Crossy]

Try this Aussie calculator, assuming you live in Darwin, similar climate to here, but fill it in honestly, with real measurements:

http://www.fairair.com.au/calculator.size.aspx

That looks quite useful without being over complex.

Comes out at about 12,000 BTU for our OP (had to make some assumptions on wall and roof materials).

[ThaiLife]

Shop condition really has nothing to do with how well they install or maintain - the units themselves should be the same wherever you buy. Smaller shops often can provide at a better price.

I have two 9k Panasonics and very happy with them. Have had LG, Central, Saijo Denki and York but would stick to Panasonic and Mitsubishi now.

I agree that may be the shop conditions may not reflect the installation workmanship , but due to a past problem using local village tradesmen, we had a house security problem , and would like to get the installation work carried out by people who don't live locally , long story.

[ThaiLife]

Any cement walls with direct sun are tremendous heat sinks that tend heat the room and take forever to cool down.

The house walls are constructed with small red bricks and skimmed with a layer of cement . But at the end of a sunny day if I put my hand on the inside of the bedroom wall , its very warm to the touch

[ThaiLife]

Try this Aussie calculator, assuming you live in Darwin, similar climate to here, but fill it in honestly, with real measurements:

http://www.fairair.com.au/calculator.size.aspx

That looks quite useful without being over complex.

Comes out at about 12,000 BTU for our OP (had to make some assumptions on wall and roof materials).

Thanks for that

Ive just filled in the calculator with the following info ( my answers are shown in Blue )

1. Region - Darwin

2. What is the ceiling area of the room you wish to cool? - 18.5 m2 ( Uninsulated tiled roof over )

3 . What is the floor area of the room you wish to cool? - 18.5 m2 ( Uninsulated suspended concrete slab enclosed under )

4. What is the height of the ceiling in the room you are cooling? - 3.7 m

5. What is the total area of the internal walls with unconditioned space adjacent? - 32.19 m2

6. What is the total area of external walls including all the windows? - 18.5 m2 ( Concrete block masonry with no insulation )

7. How large are the windows? - 2.56 m2 ( West - Externally shaded ) + 2.56 m2 ( North -Externally shaded )

8. How many people will be using the room? - 2

Calculated answer = 3kw

convert kw to BTU ( convert kW to BTU multiply by 3414 )

Required BTU = 10,242

I use this online calculator for the m2 area

http://www.online-calculators.co.uk/diy/roomarea.php

How do my figures look

[Crossy]

Try this Aussie calculator, assuming you live in Darwin, similar climate to here, but fill it in honestly, with real measurements:

http://www.fairair.com.au/calculator.size.aspx

That looks quite useful without being over complex.

Comes out at about 12,000 BTU for our OP (had to make some assumptions on wall and roof materials).

Thanks for that

Ive just filled in the calculator with the following info ( my answers are shown in Blue )

1. Region - Darwin

2. What is the ceiling area of the room you wish to cool? - 18.5 m2 ( Uninsulated tiled roof over )

3 . What is the floor area of the room you wish to cool? - 18.5 m2 ( Uninsulated suspended concrete slab enclosed under )

4. What is the height of the ceiling in the room you are cooling? - 3.7 m

5. What is the total area of the internal walls with unconditioned space adjacent? - 32.19 m2

6. What is the total area of external walls including all the windows? - 18.5 m2 ( Concrete block masonry with no insulation )

7. How large are the windows? - 2.56 m2 ( West - Externally shaded ) + 2.56 m2 ( North -Externally shaded )

8. How many people will be using the room? - 2

Calculated answer = 3kw

convert kw to BTU ( convert kW to BTU multiply by 3414 )

Required BTU = 10,242

I use this online calculator for the m2 area

http://www.online-calculators.co.uk/diy/roomarea.php

How do my figures look

I don't know how much difference it would make, but you may need to swap N and S facing windows / walls as we are in the Northern Hemisphere Oz is in the southern.

[IMHO]

Try this Aussie calculator, assuming you live in Darwin, similar climate to here, but fill it in honestly, with real measurements:

http://www.fairair.com.au/calculator.size.aspx

That looks quite useful without being over complex.

Comes out at about 12,000 BTU for our OP (had to make some assumptions on wall and roof materials).

Thanks for that

Ive just filled in the calculator with the following info ( my answers are shown in Blue )

1. Region - Darwin

2. What is the ceiling area of the room you wish to cool? - 18.5 m2 ( Uninsulated tiled roof over )

3 . What is the floor area of the room you wish to cool? - 18.5 m2 ( Uninsulated suspended concrete slab enclosed under )

4. What is the height of the ceiling in the room you are cooling? - 3.7 m

5. What is the total area of the internal walls with unconditioned space adjacent? - 32.19 m2

6. What is the total area of external walls including all the windows? - 18.5 m2 ( Concrete block masonry with no insulation )

7. How large are the windows? - 2.56 m2 ( West - Externally shaded ) + 2.56 m2 ( North -Externally shaded )

8. How many people will be using the room? - 2

Calculated answer = 3kw

convert kw to BTU ( convert kW to BTU multiply by 3414 )

Required BTU = 10,242

I use this online calculator for the m2 area

http://www.online-calculators.co.uk/diy/roomarea.php

How do my figures look

I don't know how much difference it would make, but you may need to swap N and S facing windows / walls as we are in the Northern Hemisphere Oz is in the southern.

You probably also need to add some BTU to everything because in Oz, all walls have studs and a layer of sheetrock on the interior side, which adds to the insulation.

[wpcoe]

Try this Aussie calculator, assuming you live in Darwin, similar climate to here, but fill it in honestly, with real measurements:

http://www.fairair.com.au/calculator.size.aspx

For some reason, I get a "502 Proxy error" when I click on the link. Seems to work for others, but not for me. Even tried via a US-based VPN.

Proxy Error

The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request GET /calculator.size.aspx.

Reason: Error reading from remote server

Apache/2.2.3 (CentOS) Server at www.fairair.com.au Port 80