Supplimenting Central AC with Window Unit

[superskaterxes]

so my wife and i like to sleep in a very cold room at night and it seems that our central AC needs to work extremely hard to try and achieve this. We live in a 3 story home in MD, about 3400sqft including the basement where our central AC is located. The unit is relatively old (about 20 years) but hasent really had any issues (house was built in 87 FYI).

We set the AC to 68 at night and when we wake up all the windows on the first floor are wet due to the temp difference (being about 75-80 at night). The basement is always freezing (partially underground) and the first floor is relatively cold but the second floor never really gets anywhere near what the other 2 floors do. We have closed the vents in rooms we never use but this doesent seem to have helped.

Does anyone see an advantage to getting a 5-8k BTU window unit for just our bedroom and leaving the AC at like 78-80 at night? am i unreasonable to think that with a central AC this old i should expect it to cool 2 floors higher just as well as the same floor its on?

I am all ears on this one. TIA!

 

[dsimatt]

I think it's a great idea and probably a little cheaper to run to, might want to consider a bigger one to try and cool more of the top floor area.

 

[superskaterxes]

Honestly we just love sleeping in an igloo so other than at night we don't use any of the other rooms upstairs.

 

[doolots]

Just install a single head mini split. Easy and cheap solution and wont burn up the power to bad.

 

[dsimatt]

What I meant was use it to get the upper floor closer in temp to the middle one to avoid the condensation issues you are having but it should work fine just cooling your bedroom.

 

[ticklechicken]

Just install a single head mini split. Easy and cheap solution and wont burn up the power to bad.

A window unit is pretty loud when you're trying to fall asleep. Some people like the white noise, so maybe it's a bonus. For me, I would go with the mini split for the reduced noise level.

 

[superskaterxes]

A window unit is pretty loud when you're trying to fall asleep. Some people like the white noise, so maybe it's a bonus. For me, I would go with the mini split for the reduced noise level.

i def need white noise when i sleep. Currently have 3 fans going in the room already so this will just be a bonus =D

 

[finn]

We used a supplemental window unit in one of the kids bedrooms for years, with no issues.

They're pretty cheap, so try it.

You can always donate it to Goodwill or Habitat if you can't handle the noise.

A lot cheaper and simpler to install than a dedicated mini split.

 

[jacob_coulter]

It's a no brainer and will also save you quite a bit of money rather than running your Central AC so much. I would just make sure you can deal with the noise and maybe buy one you can take back if it doesn't work for you. The compressor is louder than most fans.

A mini split would probably be the perfect solution as they run so much quieter but unless you can install it yourself, it's going to be quite a bit more expensive. Buy you could also have an inexpensive way to heat your bedroom at night in the winter.

 

[nh_yota]

IMHO the older Panasonic window units are much quieter than the newer big box store units like LG and Frigidaire, so I would look on Craigslist for a used one in the appropriate size. Unfortunately Panasonic got out of the window a/c game a few years ago because their units were top notch and last forever.

I live in a 200 year old house without central a/c so the installation and removal of window shakers is an annual ritual. Other than sizing, the most importance difference between models is whether or not you need to slide the carriage out of the frame to mount the unit in the window. Most smaller one-room units (5-8k BTU) can be mounted in the window without having to remove and replace the interior carriage.

In addition to the older Panasonics, I have a newer 10k Frigidaire from Lowes that I bought off CL two years ago from someone moving out of their apartment. It's not the quietest unit in the world but it's a one-piece unit that doesn't need to come apart to be mounted in the window. The automated energy-saving controls actually work pretty well and it's the first window a/c that I've ever left turned on for weeks at a time because it controls itself like a central a/c.

Another piece of advice is to pick the right size unit for the room. The problem with window shakers is that they may cool down a room just fine but they do not maintain humidity very well, especially if they are oversized and cycle too much.

 

[gungatim]

have you tried using a ceiling fan on low at night in the bedroom? we have a similar issue, 3-story, close the vents in the basement, main floor (where the tstat is located) gets plenty cold but upstairs not so much. we should have done a zoned system, or at least put a 2nd t-stat on the top floor that takes over at night but hindsight. (still may be an option for you). the fan works well for us, a little white noise and definitely cools the BR down while we sleep.

 

[zmaxmotorsports]

Have you had the ac serviced?

 

[Falcon67]

Just install a single head mini split. Easy and cheap solution and wont burn up the power to bad.

This. Window units eat power. A mini will also have a much lower background noise level.

 

[superskaterxes]

have you tried using a ceiling fan on low at night in the bedroom? we have a similar issue, 3-story, close the vents in the basement, main floor (where the tstat is located) gets plenty cold but upstairs not so much. we should have done a zoned system, or at least put a 2nd t-stat on the top floor that takes over at night but hindsight. (still may be an option for you). the fan works well for us, a little white noise and definitely cools the BR down while we sleep.

yes we have 3 fans going lol

Have you had the ac serviced?

the system was recharged last summer but i never had any leak detection done on the ducts or anything so that could be an issue. The majority of the house has zero issues cooling so i suspect its just difficult to cool 2 levels higher than where the AC actually resides

 

[Greeny]

Before you install another AC and electric bill multiplier, have you tried manipulating your vents? I'm like you and like sleeping in an icebox. My nightly routine includes checking for locked doors, and moving entry type rugs over three of my ground floor HVAC registers (floor vents). This forces more of the AC air upstairs and quickly chills down the bedrooms. In the morning, we simply move the rugs/mats off the registers.

 

[nh_yota]

I am not surprised that you are having cooling issues in a 3-story house. Most HVAC systems are not designed and installed properly so it's more common than people think to have issues right from the start. A window a/c will definitely solve the problem in the short term but you should look into zone controls and dampers in the duct work if it's sized correctly to begin with. Most of the supply air should be going up to third floor anyway because heat rises.

 

[PsRumors]

Go to HVAC-Talk.com, find a competent contractor in your area and figure out what you need. We lived off window units for several years after getting hosed on a new Trane, long story. We finally had all our issues with the HVAC in the house corrected and a new unit properly zoned installed. The electric savings will pay for the unit in 5 years and we are much more comfortable.

You likely have duct work issues that may be able to be resolved relatively inexpensively

 

[Greeny]

You likely have duct work issues that may be able to be resolved relatively inexpensively

Yup, this is what I have. My system isn't zoned or balanced correctly. I had to do some trial and error to figure out how many vents to block off, and which ones. We were closing the vents at first, but that got to be a pain real quick. Now we just drop the rubber backed mats over the three in the summer. In the winter we actually block off one of the master bedroom vents and a bathroom vent all winter. It's not as elegant as having the system 'fixed right', but it's cheap and easy and effective.

 

[Gila Monster]

Even if your 20 year old Central AC is working perfectly, it should be cheaper to have a window unit than cooling a 3 story home when you're just using the one bedroom at night. Especially if you like it really cold.

Just seems to me to be a much cheaper and easier solution

 

[M-technik-3]

Might want to consider zoning your house at some point or maybe doing a minisplit for the bedrooms that way the main ac can rest at night.

But a window unit is cheap way of getting it done. I hate the noise, tinnitus bugs me so I wear ear plugs to bed to kill road noise and the ac noise.

 

[superskaterxes]

Even if your 20 year old Central AC is working perfectly, it should be cheaper to have a window unit than cooling a 3 story home when you're just using the one bedroom at night. Especially if you like it really cold.

Just seems to me to be a much cheaper and easier solution

This was my exact thought process. I ordered an 8k unit and I'm going to do some before and after kwh measurements using just the central ac and then the window unit to see if I can tell a difference over say a weeks time.

Whenever this AC does die I will be sure to get a multi zone unit and correct any duct issues

 

[jhelrey]

I thought about doing the same thing. I don't have the condensation issues but my bedroom door is locked at night so that doesn't help.

 

[bubinga]

A window unit is pretty loud when you're trying to fall asleep. Some people like the white noise, so maybe it's a bonus. For me, I would go with the mini split for the reduced noise level.

Some are pretty quiet too, lMHI.
I like a white noise too
I like when the furnace is running.

Sent from my MotoG3 using Tapatalk

 

[PsRumors]

This was my exact thought process. I ordered an 8k unit and I'm going to do some before and after kwh measurements using just the central ac and then the window unit to see if I can tell a difference over say a weeks time.

Whenever this AC does die I will be sure to get a multi zone unit and correct any duct issues

You likely won't need 8k btu. When we were running on window units we could cool 800 sqft with 6k. I believe it is because there is no temp loss through the duct, just dumping the cold air right where it is needed

 

[abgiles]

I did this exact thing for a number of years. Works well on 2 story homes. We had the same exact issue. Definitely cut down on the power bill.

 

[Marctrees]

I thought about doing the same thing. I don't have the condensation issues but my bedroom door is locked at night so that doesn't help.

 

[tonyprovo723]

Besides playing with the vents, play with the the returns. You need to **** the hot air from the upstairs as well.

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[mpire]

I installed a 3/4 ton minisplit in the master bedroom years ago and did a write up on here somewhere. Costs were about $1100 and most of it was covered by tax rebates and power company incentives for efficient units. Mini-splits are regular AC units so they qualify for the same credits.

That being said, I keep the house at 80 during the day and at night I turn it up to 85 and turn the bedroom unit down to 70 because I like it cold. My power consumption was cut in half.

Cooling the top floor adequately requires the bottom floor turn into an icebox, and that's expensive. Small mini-split is worth it, and mine has paid for itself at least 10x over.

 

[Jim_No_Garage]

A lot cheaper and simpler to install than a dedicated mini split.

Until it falls out of the window while plugged in. Then it rips the power cord from the unit and when Joe Homeowner tries to reattach the power cord he does it wrong and fries the unit! DAMHIKT!

Cheers

Jim

PS: My Dad has a window unit in the bedroom he sleeps in - he run's that as needed and keeps the central A/C at a more moderate temp. Works for him.

 

[mpire]

To be fair though, the mini-split will be much more efficient and qualify for rebates that the window unit will not.

So in the short and long run the mini split is the cheaper and smarter way to go.

Assuming you do the install yourself, AC companies really gouge you for what is a really simple install.

One hole in wall, one wall bracket, one pad for condenser, one power wire, and two refrigerant lines. That's really all that's involved. Easily a lazy Saturday morning project.

 

[James-W]

Until it falls out of the window while plugged in. Then it rips the power cord from the unit and when Joe Homeowner tries to reattach the power cord he does it wrong and fries the unit! DAMHIKT

How does it fall out of the window if it is installed properly?

 

[maustarman]

I installed a 3/4 ton minisplit in the master bedroom years ago and did a write up on here somewhere. Costs were about $1100 and most of it was covered by tax rebates and power company incentives for efficient units. Mini-splits are regular AC units so they qualify for the same credits.

That being said, I keep the house at 80 during the day and at night I turn it up to 85 and turn the bedroom unit down to 70 because I like it cold. My power consumption was cut in half.

Cooling the top floor adequately requires the bottom floor turn into an icebox, and that's expensive. Small mini-split is worth it, and mine has paid for itself at least 10x over.

I'm really interested in this ...
My house keeps the downstairs cold and the upstairs is almost 10 degrees higher.
Any idea where I can find the write up you did ?

Thank you


Sent from my iPhone using Tapatalk Pro

 

[SMKS]

We used to use a window AC unit in our bedroom. We'd run the central air during the day and just the window unit at night. Worked great.

Now we have a kid, so for various reasons we have to cool the entire house, not just the bedroom.

 

[6768rogues]

I think your idea is good. The small amount of noise from a window shaker does not bother me and would bridge you over to the time when you want to spend big money on a new system and redesign. Be careful about closing too many vents, you might make the system freeze.
I might do it for our house in Florida. We are there for a few months in the winter and sometimes need air conditioning, but not always. If we cool the whole house and use the pool, it is cold when going inside the house. I would like to just AC the master bedroom and most of the time we could leave the central AC off. At least until April.

 

[rt dak]

68? I thought you said you liked it cold?

 

[soob]

Mini splits' efficiency is overrated, at least if you want the room COLD and you're just running it at night. In a bedroom that's cooled only at night, a mini split will NEVER pay for itself even if you DIY the install.

Plus the white noise from a window unit helps you sleep when the damn kids won't go to bed or the Mrs. gets up in the middle of the night to pee.

It's a proven fact (and attested by lots of people) that cool nighttime temperatures (< 67) improve your sleep.

But that temperature will cause condensation on your windows and roof in many places if you cool the whole house that way. Not to mention that it burns up electricity.

Also remember that window unit ratings (EER) aren't comparable to mini split ratings (SEER). Generally it's something like EER x 1.25 = SEER. So an 11 EER window unit is approximately as efficient as a 14 SEER mini split.

 

[6768rogues]

68? I thought you said you liked it cold?

Only until I get frost on my balls.

 

[superskaterxes]

Hey guys i just wanted to update this thread. I ended up getting an 8K window unit and more or less turned off the house AC at night. The room gets reasonably cold (the lowest it goes is 60 which still isent cold enough for me =P) and i dont wake up to the rest of the house being freezing for no reason.

I havent been able to tell much from the new and old electric bills because of the changing temps but im sure its still more efficient.