Hi

My condo has 4 windows all facing south east and i am on a low floor.

I have two x 45 sqm rooms one is above the other (duplex connected with stairs and no door).

 

I have 2 inverter ac units one in each room. 24k btu each.

 

I have found that in order to have upstairs cool, i need to turn on the downstairs unit as well. Since heat rises the single 24k cant effectively cool the heat out of two rooms.

 

As well as trying to find a way to install a door between the two rooms, i am also considering tinting the windows. I was shown a variety of films from 80b per/sq foot. That was for a 3m brand, i beleive there are cheaper.

 

Is this going to be cost effective for me? My power bill is now around 4k per month as i like to keep both rooms at around 22 degrees most of the time

 

My rooms dont get much direct sunlight.

 

Thanks

Since you write "My rooms don't get much direct sunlight.", I am not sure why you would want to tint your windows? The whole point of tinting is to reflect sunrays away to keep the interior more cool. But without sunlight, that seems unnecessary. Rather invest in double glazing windows for insulation against the outside warmth. 
Agree with the door though, if you only need one room cooled down.

 

Yup ^^^, with no direct sunlight I doubt tinting your windows will help much, unless you want additional privacy.

 

Keeping the cold air "upstairs" is going to be your priority, even a reasonably heavy curtain should help a lot (and be far easier than a door).

 

You could also try gradually increasing the temperature to acclimatise to hotter weather. After 17 years we run our A/C at 28C any colder and Madam rolls up in the comforter.

22 minutes ago, Crossy said:

After 17 years we run our A/C at 28C any colder and Madam rolls up in the comforter.

Yeah...if you need to keep your units at 22 to feel cool usually that means your AC units are not working efficiently and need a major cleaning and/or recharge. Most modern units that have been sized appropriately will keep you cool at somewhere from 26 to 28 as the optimum range for cooling and cost effectiveness. Unless you're actually Mr. Freeze from Batman, then I take  it back.

5 hours ago, CrossBones said:

I have found that in order to have upstairs cool, i need to turn on the downstairs unit as well. Since heat rises the single 24k cant effectively cool the heat out of two rooms.

Yes...your cool air from upstairs is all ending up downstairs, so by cooling the downstairs you change the entropy equation and there is no need for cool air to displace the downstairs hot air. Finding a way to block off the two areas is your best bet.

OP, it may sound counter-intuitive but you may be able to increase the overall efficiency with fans. At the moment any hot air will rise and any cold will fall etc. If you force the hot air down or the cold up, it will become more like a single space rather than two spaces.

Or find the highest point and extract the hot air out.

Another option if allowed, and if not already done might be to paint your exterior walls white to reflect more heat.

 

Or curtains with the silver reflective backing. This will serve two purposes. reflect some heat back from the outside, and provide insulation to try and prevent cooling loss.

 

install a curtain or door between the two rooms?

 

More expensive options:

 

(1) Have you checked that your A/C units are correctly sized for the rooms?

 

(2) Depending on the size of your windows and. Too small and  it might not make much difference. You could look for double glazing with pre installed spectrally selective film to reduce solar gain. This film doesn't have to be tinted, but reduces solar gain. infrared.

The film is normally added at assembly, to the glass in the space between the two sheets. But you have to order for the selected purpose. Either keeping heat in the room for cold climates, or keeping heat out for hot climates. This dictates which of the two inner sides of glass will have the film attached.

 

Edited June 20, 20215 yr by phetphet

I'm no expert!  Cheap might be the problem to solve the problem? 24K BTU to cool a room it seem you are trying to use power to force the rooms to be cool at 22 especially thinking you can use air from downstairs hoping it rises to cool the upstairs.

 

This is like my old school brother who house heater was broken so he turn on his oven to heat his house thinking the heat would rise?  Or my father once car brought down at night he pull up the hood without a flashlight use his cig lighter? 

 

As for the door upstairs you can get a custom cut sliding partisan to close the gap for less than 2000 baht. Cool is all in the mind condition yourself and dial it down to 26-28 you will save right there. My home bill is near 8000 a month ( don't ask me to explain )  when my daughter in law first came to live with us, she came from nothing, sleeping on the floor with just one fan for the entire family she thought the more the better never had so much this was applied to everything toothpaste, shampoo, she blew through a large tube a day when it came down to A/C she down it to 18 it was a mine game with her I slowly tick it up each day today it is at 28 yet she still thinks it is at 18?  ????

 

Cheap before you spend more money just cover the windows with paper and see if it works before spending more money on nothing?

Edited June 21, 20215 yr by thailand49

Tint won't work, one would have to use aluminium foil to be effective. Just hop into any deep-tinted car that's been standing in the sun if you want proof.

I run my aircons at 26 C, and am very comfortable. My Thai GF complains it is too cold.  Perhaps the OP should consider acclimatizing to Thailand.

On 6/20/2021 at 7:16 AM, Peterw42 said:

OP, it may sound counter-intuitive but you may be able to increase the overall efficiency with fans. At the moment any hot air will rise and any cold will fall etc. If you force the hot air down or the cold up, it will become more like a single space rather than two spaces.

Or find the highest point and extract the hot air out.

Extract the hot air?? Open the windows upstairs. ????????????

1 hour ago, thailand49 said:

Cheap before you spend more money just cover the windows with paper and see if it works before spending more money on nothing?

deffo the way to go first up

On 6/20/2021 at 1:39 AM, CrossBones said:

As well as trying to find a way to install a door between the two rooms,

You need to hinder the cool air from upstairs go down and make it harder for the warm air from down stairs reach you room upstairs. Or run both ACs to have enough cooling capacity.

On 6/20/2021 at 2:06 AM, tonray said:

Unless you're actually Mr. Freeze from Batman, then I take  it back.

 

That gave me a chuckle.

Weve had dozens of air- conditioners in our house.  I used a Daikin 24 btu inverter for about two weeks.  It couldn't keep up with the heat and bought a Mitsubishi 24 btu.  I was told the inverters struggle during extremely hot days.   

 

I would put the two inverters in one room then add a Mitsubishi into the replacement room or the room you sleep.

 

Its not cheap but you'll be comfortable for the next 10 years.  You'll save electricity because the condenser won't run as long and struggle during the extreme heat.

 

Below is a screenshot:

 

 

Looks like most of the options have been covered already. Just a note on tinted/reflective film. If you are already low on incoming light, you likely be significantly lower with an effective film installed. And, in my experience, only the best quality American-made film is worth installing.

Using a curtain as a divider will work for keeping the lower floor cool, but it won't work well for upstairs since the hot air will leak to upper level (from upper/lower or sides of curtain) 

I had a simiilar problem in trying to keep the heat out. I took the advice of a Belgian gentleman, whose business is nothing but films and had him install heat reflecting films only. 
There was almost no tinting of windows but pure heat reflection, for a total of 6 windows and door with a total area 25m2 I paid something like just below THB 30'000, i.e. THB 1'100 per actual squaremetre. He came over with his workers and had all the films up within half a day. 
Many years ago and the films are still in mint condition, the investment was paid back with less than a year. 

I don't know if he is still in business but here would be his latest coordinates I have on file:

Mr Jos Van Bogget
222/89 Moo 7, Siam Country Road, Cholburi
phone: 084-676'26'50
email: [email protected]

The heat film installed was a "SCP NICR20" at THB 1'100/m2. 

Good luck. Should he be no longer in the business (due to ongoing economic f/ups) then you might find anyone else selling above film. Ensure though that they also put it up. Not rocket science with dishwasher-liquid-water-spray and brushes but something you do NOT want to try yourself. 

Maybe it's best you move............?

On 6/20/2021 at 2:40 AM, Crossy said:

Yup ^^^, with no direct sunlight I doubt tinting your windows will help much, unless you want additional privacy.

 

Keeping the cold air "upstairs" is going to be your priority, even a reasonably heavy curtain should help a lot (and be far easier than a door).

 

You could also try gradually increasing the temperature to acclimatise to hotter weather. After 17 years we run our A/C at 28C any colder and Madam rolls up in the comforter.

22 degrees is far too low.

26 is fine compared to outside temp. And the prime function is to dry the humidity, which is the main factor for Discomfort. 

On 6/21/2021 at 4:21 PM, fakser said:

22 degrees is far too low.

26 is fine compared to outside temp. And the prime function is to dry the humidity, which is the main factor for Discomfort. 

 

You can't dry the humidity, you have to remove it.

 

I like 23C

I had an older condo in Ban Chang (near Rayong) and about 8 years ago I went through the same exercise. Phone up different Car places etc--the price was horrific. In the end I found it Cheaper to replace the glass--sounds mad I know, but  I got thicker (great for blocking the sound) and tinted glass for a cheaper price then I was quoted on tinting.