Is an inverter air conditioner more efficient than a window air conditioner?

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Good afternoon,

I would like to cool a room which is around 72 sq ft. I currently cool it with a general electrics 5000 btu window ac with eer rating of 11 and 455 watt power consumption. I was wondering if a 9000 or 12000 btu mini split inverter air coinditioner would be more efficient in energy consumption. the inverters can go as low as 3000 btus sometimes so that means if the 9000 btu inverter starts at max consumption until the room is at desired temperature and stays afterwards at 3000 btus to maintain desired temperature, over the long run it would probably be more economical as the inverter would stay on at 3000 btu which is a lower power consumption than the window ac which is always at 5000 btu. Which would be more efficent the window 5000 btu non inverter ac or the 9000 or 12000 btu inverter mini split ac?

thanks
 
which is more efficient, 6000 btu running 50% of the time or 3000btu running 100% of the time?

You really should look at the power consumption for the different btu levels.
 
If installed with insulated line set and with the correct charge (VERY Important) a mini split inverter unit will be more efficient than a window unit, particularly at high temperatures. I suspect it will never save enough energy to pay for the extra cost.

Rod
 
The cheaper 9k mini splits should be able to run as low as about 35-40%. This is probably the max it will run in your situation. See if you can get a 7k BTU unit. Not sure if that small of a size is made in the cheaper equipment.
 
Inverters will save money and they can be had in window units too. Another energy saving item to look for are infrared or motion sensors that detect if you are in the room. There are several technologies that work to save money and energy.
 
Yes, those window shakers leak air terribly. Doesn't matter how well you tape up the opening the cabinets bypass all kinds of outside air. Mini-splits don't leak any air. Dig around on ebay, you can find the 9000btu inverter units for $4-500 new and pre-charged. Rent a vacuum pump and get a tube of nylog. They take about 3-4 hours to install if you take your time and hire the electrician. Quiet enough that you won't notice it running once the room comes down to temp.
 
I'll take that bet.de[emds pm

I'll take that bet.
depends on your energy cost. And the installation cost and unit differential cost. The window unit is about 130 now. Mini split google says 750. Run 220 line by electrician at 90 an hour. Line set" Installation labor So how much installed, 1000. 870 buys a lot of electricity. Will it run 10 years with out a repair, even a capacitor? Vs throw out the window unit and get another. At .12 a KW probably negative payback.
Rod
 
Look at the seer rating and the btu. I think typically mini split would be more efficient because the seer number is higher (say 21 seer, means you use 1 unit of electricity to move 21 unit of heat out) vs window ac of 16 seer (1 unit of electricity move 16 unit of electric). If sized right and not short cycling from what I heard it can make 20% difference in efficiency.

Then there's installation cost, is it worth putting in a lot of money ripping out existing working system or wiring electrical (maybe you already have the electrical for mini split too).

This comparison is highly location specific. I know some high rise have window specifically build for window unit and not the US style pull up window jam an AC in there hack. I have also seen high rise with premade location for hanging mini split these days too, and wiring cost + electrician cost + repair cost vs throw away old one get a new one from Walmart cost.

72 sqft is small even by Asia standard and 5000 btu is small AC even by window unit standard. You are likely talking about a very small energy cost vs a high installation labor cost regardless of size.
 
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which is more efficient, 6000 btu running 50% of the time or 3000btu running 100% of the time?

You really should look at the power consumption for the different btu levels.
In this case 3000 btu 100% of the time, if the same seer.
 
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72 sqft is small even by Asia standard and 5000 btu is small AC even by window unit standard.


I wondered about those figures as well.

One can find a basic calculator online to determine the size of air conditioner needed.

 
Window units - cheap, cost more to run, easy to fix (throw away install a new one) little down time, not made to run below 60*f being inside a office build not a problem and more noise.
minis - more upfront cost, cheaper to operate, more cost for service ( to clean, parts are not always available) more down time.
 
I wondered about those figures as well.

One can find a basic calculator online to determine the size of air conditioner needed.

It is hard to calculate for room that small without knowing the rest of the "building" in heat capacity and the sun light / shade / hour of operation etc. Usually you can go by experience with nearby people or temperature difference between inside / outside.

I remember when I was buying window AC back in HK they sell them by horse power, and they increment by 1/2 HP at a time and starting with 1 HP, so it is not like you can do a manual J and then go 1/2 ton at a time in the US. I think in the US they don't sell anything smaller than 5000 btu, rating for 100-300 sqft. So for 73 sqft room 5000 btu is likely the only reasonable choice.

Come to think of it, for something so small as a constant load getting a mini split may not be worth it, unless it is a room full of heat generating stuff like server. For server room you will likely just add the amount of watt you will generate to the AC capacity, pretty easy.

 
5200 btu Window ac specs
20210418_104942.jpg


12000 btu inverter mini split specs
20210418_142138.jpg
 
It is hard to calculate for room that small without knowing the rest of the "building" in heat capacity and the sun light / shade / hour of operation etc. Usually you can go by experience with nearby people or temperature difference between inside / outside.

I remember when I was buying window AC back in HK they sell them by horse power, and they increment by 1/2 HP at a time and starting with 1 HP, so it is not like you can do a manual J and then go 1/2 ton at a time in the US. I think in the US they don't sell anything smaller than 5000 btu, rating for 100-300 sqft. So for 73 sqft room 5000 btu is likely the only reasonable choice.

Come to think of it, for something so small as a constant load getting a mini split may not be worth it, unless it is a room full of heat generating stuff like server. For server room you will likely just add the amount of watt you will generate to the AC capacity, pretty easy.



I had the same experience in other parts of Asia. They went by horsepower.

I went with mini splits but the rooms were larger. For this size of room a window unit would be fine. Get a inverter window unit. LG makes them as do other manufacturers. Easy to clean too. Just remove the unit and take it outside to clean. Splits require cleaning on both the inside and outside units. Inside requires plastic covers to keep water from going all over the room.

The biggest advantage to a split is the quiet running of the unit.
 
So both are R410a.

11eer on the window AC, the LG VM122CW is 16 SEER according to spec on website. The LG can go to as low as 3000 btu and it is inverter based.

Assuming we are talking about only energy cost the LG wins hands down. Assuming you get the window AC already installed and paid for it wins enough not to bother switching out. Assuming you have to pay for the window AC (say you bought or rent the place and the old tenants / owner will take away the window AC) and you know how to install the LG mini split then I'd go with the LG mini split.

How much is the installation labor? I know labor is much cheaper outside US and US labor is ridiculously high, makes most jobs pointless no matter the savings.
 
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