Air Conditioning usage

[Davejf2017]

I would like to know what watts a hour like say a 30 watt light bulb uses in a hour that a 18,000 btu Mitsubishi inverter Mr Slim air conditioning unit uses in 1 hour it is 3 years old in good working condition.I have looked on google but it all gets confusing.Answers in plain understandable English please.Thank you 

[Crossy]

Your 18000 BTU aircon will use about 1800W when the compressor is running.

 

If it's working properly, correctly sized for the room and not set to arctic temperatures then the compressor will probably be on 50% of the time in the current weather.

 

So you're looking at 0.9 units per hour. Your 30W lamp will use 0.03 units per hour.

 

A/C about 30 times what the lamp would use.

 

[tonray]

Turn off everything else for an hour and mark your meters beginning and ending numbers. It depends on settings, how hot it is, size of room...etc etc etc. Just read your meter ...the only true way to see real usage.

[HashBrownHarry]

1 minute ago, Crossy said:

Your 18000 BTU aircon will use about 1800W when the compressor is running.

 

If it's working properly, correctly sized for the room and not set to arctic temperatures then the compressor will probably be on 50% of the time in the current weather.

 

So you're looking at 0.9 units per hour. Your 30W lamp will use 0.03 units per hour.

 

A/C about 30 times what the lamp would use.

 

I'm led to believe that the rule of thumb for sizing A/C is 1000BTU per sqm, is that correct?

 

It's seldom that A/C's are sized correctly for the rooms they're in.

[Crossy]

3 minutes ago, HashBrownHarry said:

I'm led to believe that the rule of thumb for sizing A/C is 1000BTU per sqm, is that correct?

It's seldom that A/C's are sized correctly for the rooms they're in.

 

The standard Thai guesstimate is 600 BTU per m², 500 if it's a bedroom.

 

[HashBrownHarry]

1 minute ago, Crossy said:

 

The standard Thai guesstimate is 600 BTU per m^2, 500 if it's a bedroom.

 

just for my info what difference does it make what room type it is? ie bedroom / living room / dungeon etc?

 

my living room is approx 60sqm, i have a 18K BTU unit at each end but i feel it's not enough with both on at this time of year.

 

Thoughts?

 

[Crossy]

@HashBrownHarry bedrooms are occupied at night when it's cooler outside so you can get away with a smaller unit.

 

60m² @ 600BTU would be 36,000 BTU which is what you have. But as others have noted there are many variables.

 

What set temperature are you using? Do the A/C compressors ever actually stop (assuming they're not inverter units)?

 

Our lounge (where I am now) is 36m² with a single Hitachi  24,000 BTU inverter (666 BTU / m²). It's fine for me, but I tend to set 28C and have a fan as well.

 

[HashBrownHarry]

Just now, Crossy said:

@HashBrownHarry bedrooms are occupied at night when it's cooler outside so you can get away with a smaller unit.

 

60m² @ 600BTU would be 36,000 BTU which is what you have. But as others have noted there are many variables.

 

What set temperature are you using? Do the A/C compressors ever actually stop (assuming they're not inverter units)?

 

Our lounge (where I am now) is 36m² with a single Hitachi  24,000 BTU inverter (666 BTU / m²). It's fine for me, but I tend to set 28C and have a fan as well.

 

During the day have one set at 16C, if it is not cool enough fire up the other bad boy.

 

The compressor stop sometimes i think.

 

I also have 2 fans in living room.

 

Also just spent a lot of money on UVPC windows with heat reducing glass which have made a massive improvement. My roof has a shallow pitch which i'm suspect about, i'm thinking about pulling down the ceiling and spraying foam insulation, think that would help as i don't know much about it?

 

Thanks.

[Crossy]

1 minute ago, HashBrownHarry said:

During the day have one set at 16C, if it is not cool enough fire up the other bad boy.

 

Yeah, I suspect that you need more cooling if you really need it that cold. I hate to think what your power bill is.

 

Last year our visitors from the UK set their bedrooms and the lounge to 16C, talk about arctic even the dogs (who do like to cool down after lying in the sun cooking themselves) wouldn't come in.

 

[KhunBENQ]

16C!!!

Are you serious?

[Crossy]

2 minutes ago, KhunBENQ said:

16C!!!

Are you serious?

 

Cue John McEnroe

[soi3eddie]

 

If you look on the condenser unit in the room it should have a sticker on it showing the specs and power consumption. I bought this new 20,500 BTU Inverter unit 6 months ago and it's much better cooling, quieter and lower power consumption than the old one. I tend to keep it on 24/25c during the day and also use a floor fan. 

 

Power consumption is stated as 1740W so 1.74KW. At current electricity rates of roughly 4 Baht per KW/HR it works out at about 7 Baht per hour in use. 

 

Edited April 30, 2020 by soi3eddie

[northsouthdevide]

The new inverter or double inverter air con use half the electricity of an old style unit. 

Each unit performance will depend on correct sizing for room, insulation and outside temp. 

Mitsu are a decent brand and should ferform well enough under the right conditions. 

As are LG and for more expense, carrier. 

[zzzzz]

btu's/hour, kws, invertor, etc etc

 

I know it cost me 10 baht to run my aircon in my 4x4 m bedroom set at 27 for 9 hours/ night over using a fan only

which is plenty cool enough to sleep under a comforter 

 

set at 16 is pure wasteful

Edited April 30, 2020 by zzzzz

[HashBrownHarry]

1 hour ago, KhunBENQ said:

16C!!!

Are you serious?

 

1 hour ago, Crossy said:

 

Yeah, I suspect that you need more cooling if you really need it that cold. I hate to think what your power bill is.

 

Last year our visitors from the UK set their bedrooms and the lounge to 16C, talk about arctic even the dogs (who do like to cool down after lying in the sun cooking themselves) wouldn't come in.

 

Power bill normally 6-8K per month

[whiteman]

4 k a month  I never thought I would hear in my life time some one asking how much a light bulb users I guess some must live on the edge

[samtab]

On 4/30/2020 at 9:08 AM, Crossy said:

Your 18000 BTU aircon will use about 1800W when the compressor is running.

 

If it's working properly, correctly sized for the room and not set to arctic temperatures then the compressor will probably be on 50% of the time in the current weather.

 

So you're looking at 0.9 units per hour. Your 30W lamp will use 0.03 units per hour.

 

A/C about 30 times what the lamp would use.

 

 

so how much would be 24 hours aircon ? thank you.

 

 

[Crossy]

2 minutes ago, samtab said:

so how much would be 24 hours aircon ? thank you.

 

With the above assumptions (and not taking account of lower night time usage) 24 hours would be about 22 units = around 100 Baht.

 

Absolute worst case, with the compressor running constantly (set temp too low) would be around double that. 

 

If you budget at 200 Baht a day you'll likely have change for a beer or two when they let you buy it again.

 

[AtlasAus]

On 4/30/2020 at 9:15 AM, HashBrownHarry said:

just for my info what difference does it make what room type it is? ie bedroom / living room / dungeon etc?

 

my living room is approx 60sqm, i have a 18K BTU unit at each end but i feel it's not enough with both on at this time of year.

 

Thoughts?

 

The trouble over here is the lack of insulation in the ceilings and walls...... Our study gets the Eastern Sun all day, you could nearly fry an egg on it ! 

Someone mentioned polyurethane as insulation, be very careful with that, very flammable......  

[sometimewoodworker]

5 hours ago, AtlasAus said:

Our study gets the Eastern Sun all day, you could nearly fry an egg on it ! 

Someone mentioned polyurethane as insulation, be very careful with that, very flammable......  

If you have a surface that gets hot enough to radiate you are going to have a difficult time with your AC. First step is to stop the heat gain. For that you need white solar reflection paint on the outside, on the inside you could use white or a silver radiant barrier.

 

if you are going to add insulation you can use polyurethane Foam any good one has flame retardant in it so is not inflammable