Window AC: to replace or not to replace

[gathermewool]

I use a 6k BTU/hr unit in my main bedroom with attached bath and walk-in closet. The 6k keeps up on hot days when already at temp, but barely. When we get home and turn the unit on before bed it has to be at least 3-4 hrs to get down into the mid 60s (where I like it) on hot days/nights (80F+). This unit was a transplant from our last place, which it was perfect (much smaller condo).

We need an 8-10k unit for sure, but the 12K Midea U-shaped (which we have two of and love for our outside space) is way cheaper than the 8 and 10K units for some reason. About $280 @ Costco.

The difference in CEER is 11.0 for the 6K and 15.0 for the 12K unit.

I like the sound of the loud 6k unit, so the quiet Midea doesn’t matter.

I’d probably sell the 6k unit for like $25 to get rid of it, so no real offset there.

I have 15 yo Sharp unit but it’s heavy af and isn’t efficient at all. I plan to sell it too.

Thoughts? I’m trying to find a CEER to CEER savings calculator.

ETA: this unit will be running around 16 hrs/day

 

[Rand]

the midea will cool much faster then slow down using less electricity not like its going to need to put out 12k btu for hours.

if the unit efficiencies were the same you might end up using more power.. but since the inverter compressor is more efficient..
you will save money.. will it pay for itself..? eventually.. but IIRC you have all electric house.. have you considered a mini split that does heat..
to lower your winter heating bill?

The payback for a few thousand worth of mini splits would be pretty fast with winter COP of 2-4 vs resistance electric (unless you keep the house warmer of course)
a COP of 2 = twice the heat for vs regular electric heating.. Most mini splits are between 2.x to ~~4 depending on outside temps.

 

[gathermewool]

the midea will cool much faster then slow down using less electricity not like its going to need to put out 12k btu for hours.

if the unit efficiencies were the same you might end up using more power.. but since the inverter compressor is more efficient..
you will save money.. will it pay for itself..? eventually.. but IIRC you have all electric house.. have you considered a mini split that does heat..
to lower your winter heating bill?

The payback for a few thousand worth of mini splits would be pretty fast with winter COP of 2-4 vs resistance electric (unless you keep the house warmer of course)

I’ve had some health issues lately, so I’m broke as a joke (not literally, but you get my point). I’m hoping for savings over a few years not ten.

ETA: this unit will be running around 16 hrs/day

 

[Rand]

I’ve had some health issues lately, so I’m broke as a joke (not literally, but you get my point). I’m hoping for savings over a few years not ten.

well i can give you aprox. usage.. I had a similar situation

my 6k conv. window ac used around 450w. my 8k midea u shaped uses 99w-325w most of the time.. if i turn it on max blast with a 90f room it tops out just over 500w.
but if you keep your house colder you will need more cooling as the temperature differential from outside will be greater.
of course this doesnt account for sunload and a bunch of other stuff.

If we knew hours per month your current unit runs .. you could get some rough calculations.

personally I'd do it for a more comfortable home.. but if you keep the house considerably colder you might not experience much energy savings.
it might also make your other window ac's use less energy .. so a super easy savings calculation isnt possible.. it might be a low enough number to be lost in the noise over the summer..

My heat pump hot water heater saves me around 40$ a month vs a conventional water heater and running a dehumidifier.

payback on a mini split or 2 would likely be 3-4 years vs resistance heat.

(yeah I jumped around alot with this post )

 

[gathermewool]

well i can give you aprox. usage.. I had a similar situation

my 6k conv. window ac used around 450w. my 8k midea u shaped uses 99w-325w most of the time.. if i turn it on max blast with a 90f room it tops out just over 500w.
but if you keep your house colder you will need more cooling as the temperature differential from outside will be greater.
of course this doesnt account for sunload and a bunch of other stuff.

If we knew hours per month your current unit runs .. you could get some rough calculations.

personally I'd do it for a more comfortable home.. but if you keep the house considerably colder you might not experience much energy savings.

Like you said, though, once the set temp is reached the unit will use very little for most of the night while it runs.

unit is on north side, so shaded most of the day. Used mostly at night, also.

My 12k unit maxes out at
Actual: 934W
(80.6F/45% RH in; 86F / 58% RH out)

I use two 12k units and can’t use the boost function because it’ll trip the breaker. I know, I know not smart.

 

[Rand]

what are your summer and winter electric bills like vs the shoulder seasons when you dont use much heating or cooling?

 

[gathermewool]

The 6k burns 540W max. Sorry, forgot I had notes on this.

 

[WobblyElvis]

or just keep doing what you are doing. Real savings are seldom as much as they claim.

or

consider....is the price of any new unit about to double? Maybe you should grab one quick!

 

[gathermewool]

what are your summer and winter electric bills like vs the shoulder seasons when you dont use much heating or cooling?

I’m a cheap bass, so I keep it in the 50s in the winter (still >$500). Even when we use almost no heat or AC, like last month, it was $323.

with that said, we keep our bedroom warmer and turn the bathroom heat up for showers and such. We also keep the whole house at 70F+ when friends and family are over (they’re weak warm bloods lol). This may sound bad, but we’d likely lose some savings with a half-split by keeping the temps up. I guess I’m fine with that, so long as I can keep my dang CT electric bills <$500 in the middle of winter.

I also keep it in the high 70s or above 80 (with plenty of fans) in the summer, which is juuuust comfortable enough in the main spaces. The bedrooms are kept much cooler.

I’ve mentioned this before in previous threads, but we have a pretty big main bedroom. TV, laptops, main desk and PC, bathroom, etc. I’m also easy to acclimate, so 50F with a beanie and a sweater on is fine for us. I have to literally yell at my kids to put on more clothes. They just aren’t bothered by the cold/heat. It’s the wife I have to keep happy, and she’s super amenable. Awesome lady…she’s controls the bedroom thermostat lol.

 

[gathermewool]

or just keep doing what you are doing. Real savings are seldom as much as they claim.

or

consider....is the price of any new unit about to double? Maybe you should grab one quick!

Good point. The Costco 12k unit is the same as it’s been for years. Who knows if that’ll change….

 

[Rand]

Good point. The Costco 12k unit is the same as it’s been for years. Who knows if that’ll change….

I dont think you can go wrong with the midea u shape unit. although I do think you could get 2-3x the heat in the winter(or save $$$) with a couple mini splits..
but if you dont got the money... I understand that.(wife has been in ER twice in 3 months $39000 and $56000 and 30+ dr visits luckily her insurance is fairly decent)

 

[loneryder]

I love that Midea unit in my home theater in the finished attic. Super quiet, runs at a very low speed after the first minute or so.

 

[walterjay]

I have a U Midea. Great machine and economical.

 

[Cujet]

I have the Medea 12K unit from Costco in my bedroom. It's been a workhorse for the last year and I do like just about everything about it. In fact when my central AC quit this winter (FL) I used that unit to cool the entire house.

Mounting it was a bit more complex than a normal window unit, and I did not use the mounting kit as described. No need. The bracket outside the window is necessary.

However, I found that I needed to tilt the unit for drainage more than I'd like. If completely level, the water would simply sit inside the unit, grow mold and not run to the outside, where it should sling on to the condenser and/or drain out. I pulled the drain plug, understanding that this reduces efficiency a touch. But it prevents nasty water accumulation and it is much more healthy to keep the unit clean.

I did use a Kill a Watt to measure consumption. It varies quite a bit, the highest I've seen is 604 watts at full load, which might be 12,000 BTU. When the unit is not working hard, it only draws a couple hundred watts. So, even with the drain pulled, the unit seems to meet its claimed efficiency.

For a real heavy load test, I would have to let the house heat up. Probably something I don't want to do right now.

 

[alarmguy]

Maybe this is better sized for your BR
15 Seer too
i get it though Costco has a larger one for less but if grossly oversized BR room will get musty
https://www.amazon.com/Midea-Inverter-Conditioner-Flexibility-Installation/dp/B08677DCKN

https://www.homedepot.com/p/Midea-8...0-sq-ft-Energy-Star-2024-MAW08U1QWT/327511952

 

[Rand]

Maybe this is better sized for your BR
15 Seer too
i get it though Costco has a larger one for less but if grossly oversized BR room will get musty
https://www.amazon.com/Midea-Inverter-Conditioner-Flexibility-Installation/dp/B08677DCKN

his current 6000btu runs for hours and hours and doesnt provide enough cooling.

Midea unit is not grossly oversized. inverter compressor can speed up and slow down.
the 12k btu unit can easily go below 4k btu

my 8k unit has a range of about 96w to 500w. I'd expect the 12k unit to run aprox 150w to 800w

 

[Cujet]

Midea unit is not grossly oversized. inverter compressor can speed up and slow down.

This is true. It runs at only the output necessary. The thing works exceptionally well.

I've been running it in the bedroom for the last 4 hours, set at 63 degrees, just to see what the current draw will be. It is now drawing 430W and it's too cold in there! If I remember, I'll check again in the AM. It does go down to about 300W sometimes. Which I assume is about 6000 BTU.

 

[goblin]

The midea is amazing but you have to make sure your windows will fit in the space between the two parts. Mine didn't (two long distance between the two sliding panes), and it was a long and compromised install.

Also, if you make a u-shaped AC - why not do it right and make it inverted U-shaped (like saddlebags riding the wall) ?

This clears the window almost completely, simplifies the mount tremendously - only positives in my book.

 

[Cujet]

Also, if you make a u-shaped AC - why not do it right and make it inverted U-shaped (like saddlebags riding the wall) ?

The condenser's water would then pool at the bottom, needing a pump. Also, my walls are nearly a foot thick.

Last night:

Initial power draw 604W
Later on 430W
Before bed 320W
This AM 270W

Bedroom Temp 62.7 this AM.

I'll be honest, I believe this window unit is more efficient overall than my 16 SEER home central AC. The home AC has a 2.5T and a 5T compressor, runs constantly and the 2.5T unit does only slightly better at cooling the entire house on modest days.

Put another way, I am quite sure 3 of these units could cool my home during the hottest summer days and use less power doing so. My 5T unit draws about 3700W at full load. The advantage is that the central air is completely silent and has superb filtration.

 

[RhondaHonda]

I really wish they made one with heat too. My basement garage is is below grade on 2.5 sides, well insulated and underneath a living space so it has minimal cooling and heating requirements. I think a 12 or 18k would be just right for me but would really like heat too. As cheap as the 12k AC is, I should give it a shot.