A/C Size

[MilwaukeeStubble]

I have an old/inefficient/barely working wall sleeve (like a window unit but with a metal box in the wall) air conditioner in my bedroom. 

The room is about 11' x 16' x  8', top floor, no attic, facing north, decently insulated with a 4' x 8' window facing north.  I live in Milwaukee so it generally doesn't get over 95* or so.

From what I can tell online this means that I should look for something in the 5000-8000 BTU range.

The problem is that the outlet that's there is a 220V 15A socket [1] and I haven't been able to find anything that uses 220V and pulls out less than 10,000 BTU.  How big of a deal is it to get the bigger one?  Can you recommend a place where I should look for a smaller one that uses 220V?

I can make a 110V unit work, especially since it's mostly used at night, but the circuit over there is already busy and I don't want to add anything more if I can help it.

Thanks for the help!

[1] http://www.justanswer.com/uploads/ElectricDoctor/2009-08-30_192959_15amp_220v_outlet.jpg

[Fishindude]

Somebody competent in electrical work can pretty quickly change that 220V outlet to 110V.   Don't mess with it if you don't know what you are doing.

Pretty much the smallest window air conditioner you can find will handle that room.  It will probably be smaller than the existing sleeve, so with a little creativity, you can just stick it in that sleeve then trim out the inside.

[KarefulKactus15]

Well,  I have nothing useful to add.   Maybe one of the HVAC technicians or Engineers can pop in and provide a rough load calculation to get your needed BTU's.


From my uneducated opinion, I would get the smallest BTU 220V unit that is closest to your needs.  The power drop is already there, may as well use it.


Even though I provided no useful information, maybe It will bump it up to the top and someone else can help....

[bdonney]

Not a big deal to get a 10k+ BTU 220v air conditioner, there's some potential cost savings it looks like to convert the outlet to 110v. If this would be your first time working with anything electrical and you don't even own a multimeter/volt meter, I probably wouldn't do it.

[Jack]

From my uneducated opinion, I would get the smallest BTU 220V unit that is closest to your needs.  The power drop is already there, may as well use it.

Not a big deal to get a 10k+ BTU 220v air conditioner

An AC that is too large will short-cycle, which is bad for efficiency, causes more wear-and-tear on the unit, and makes it harder to control humidity.

https://www.energystar.gov/ia/home_improvement/home_sealing/RightSized_AirCondFS_2005.pdf

[Spork]

Okay, I know absolutely nothing about sizing HVAC systems.  But I did live for 5 years in a small space with 120v window units.  Let me tell you: They can be terribly inefficient.  They don't have the same ratings (SEER) as traditional split compressor systems.  They typically use EER -- which is mathematically related to SEER, but unless you take your calculator, you won't be able to compare them.

While Jack is correct on making sure they are right-sized... I would look long and hard for a nicer, more efficient 240v unit over the various Hampton Bay quality level units you'll find at the local Lowes/Home Depot.

My electricity bill was cut in half moving from a 600sqft structure cooled by window units to a 2500 sqft structure cooled by 2 traditional units.  (There were definitely other improvements involved.... not just A/C.  But still...  That is a big reduction.)

[bdonney]

From my uneducated opinion, I would get the smallest BTU 220V unit that is closest to your needs.  The power drop is already there, may as well use it.

Not a big deal to get a 10k+ BTU 220v air conditioner

An AC that is too large will short-cycle, which is bad for efficiency, causes more wear-and-tear on the unit, and makes it harder to control humidity.

https://www.energystar.gov/ia/home_improvement/home_sealing/RightSized_AirCondFS_2005.pdf

While true, I ignored that truth because if 5-8k is recommended and he gets a 10k, short cycle issues isn't really a concern, it's not enough of an overkill. Plus they have safety's built in, just like your refridgerator or freezer. It will wait 5+ minutes before turning back on. But yes, you would want to get something as small as possible if you stick to 220V. I'm just saying it's an option if you don't want to mess with changing the outlet to 110V and I wouldn't worry about 10k BTU being too big.

[KarefulKactus15]

My first post was pretty pathetic.  Lets talk $

220V ACs are more expensive, and overkill.  I imagine you want one of the 5,000 BTU units that sell for around 150$.   You say your other 120V outlet is "busy".  How busy? How many watts/ amps do you already have plugged in?  If you dont know, list the items and we can guestimate....

http://www.amazon.com/Frigidaire-FFRA0511R1-Window-Mounted-Mini-Compact-Conditioner/dp/B00W2KG92Y/ref=sr_1_1?s=home-garden&ie=UTF8&qid=1463178146&sr=1-1&keywords=window+ac

This is the top rated 5k BTU ac on amazon.  The reviews claim around 5 amp current draw.  I believe most house circuits are rated for more than that.    Id like to know what all you have connected to your 120v circuit, and also what the breaker is rated for ( I dont think your supposed to go above 80% rated capacity)


If using the current 120v isnt an option, you get to weigh the cost of buying a 220v and being overkill vs the price of someone swapping the current 220v to 120v and then buying a 120v AC.....

 

[sokoloff]

If you have a 240VAC circuit that has a neutral (typically would have 4 pins on the plug, line1, line2, neutral, and ground), then it's trivial to pull 120VAC from it safely. If you only have line1, line2, and ground (no neutral), it's also easy to do so it "works", but I'd say it's not safe to do and certainly would not meet code working only at the outlet (you would also need to do work inside the service panel).

The pic you included only has 3 pins exposed, so you'd need to pull the outlet out and see if it was fed with a 3-conductor (plus ground) or 2-conductor (plus ground). Mostly likely the latter, so you'd have a small amount of work to do on the service panel side as well. (Generally, switch to a single pole breaker, and put one of the now line conductors to the neutral bus bar, blank off the opening left by the now narrower breaker, and change the outlet in the room.)

[MilwaukeeStubble]

Somebody competent in electrical work can pretty quickly change that 220V outlet to 110V.   Don't mess with it if you don't know what you are doing.

How difficult is it?  Is it as simple as replacing the outlet and replacing one of the wires with a neutral? Or do I have to do something in the panel?

I've done basic stuff (replacing outlets, switches and light fixtures mostly) but I wouldn't call myself "competent in electrical work." 

[MilwaukeeStubble]

My first post was pretty pathetic.  Lets talk $

220V ACs are more expensive, and overkill.  I imagine you want one of the 5,000 BTU units that sell for around 150$.   You say your other 120V outlet is "busy".  How busy? How many watts/ amps do you already have plugged in?  If you dont know, list the items and we can guestimate....

I'm not sure what it all adds up to but it runs from the front hall, through the main bathroom, the bedroom and one wall of the living room.  So there's

7 light bulbs (LED or CFL)
hair dryer
bath fan
TV/receiver/etc
4 cu ft fridge
convenient outlets for the vacuum

I suspect it's a 20 amp breaker (it's definitely 20 amp wiring) but keep forgetting to check.

There's a few other things but nothing that would be used on days the A/C is on.  Even with that we might be able to get away with it as the A/C would mostly just be for hot humid nights and everything else isn't on at the same time anyway.

http://www.amazon.com/Frigidaire-FFRA0511R1-Window-Mounted-Mini-Compact-Conditioner/dp/B00W2KG92Y/ref=sr_1_1?s=home-garden&ie=UTF8&qid=1463178146&sr=1-1&keywords=window+ac

This is the top rated 5k BTU ac on amazon.  The reviews claim around 5 amp current draw.  I believe most house circuits are rated for more than that.    Id like to know what all you have connected to your 120v circuit, and also what the breaker is rated for ( I dont think your supposed to go above 80% rated capacity)


If using the current 120v isnt an option, you get to weigh the cost of buying a 220v and being overkill vs the price of someone swapping the current 220v to 120v and then buying a 120v AC.....

You're not supposed to put a window unit in a wall sleeve because the sleeve blocks the side vents.  A window unit is designed for air flow on the sides but a through the wall unit is designed so that all the air goes in and out the back panel.

I can be convinced that it doesn't matter but everything I've seen makes me think that's a no-go.

The cost difference between an otherwise identical 120V and 220V units seems to be about $20.  Listed power usage was the same for both as well. Obviously lower BTU ones are a bit cheaper, but 5000 to 10000 BTUs seems to be $100 or so

[MilwaukeeStubble]

Somebody competent in electrical work can pretty quickly change that 220V outlet to 110V.   Don't mess with it if you don't know what you are doing.

How difficult is it?  Is it as simple as replacing the outlet and replacing one of the wires with a neutral? Or do I have to do something in the panel?

I've done basic stuff (replacing outlets, switches and light fixtures mostly) but I wouldn't call myself "competent in electrical work."

The pic you included only has 3 pins exposed, so you'd need to pull the outlet out and see if it was fed with a 3-conductor (plus ground) or 2-conductor (plus ground). Mostly likely the latter, so you'd have a small amount of work to do on the service panel side as well. (Generally, switch to a single pole breaker, and put one of the now line conductors to the neutral bus bar, blank off the opening left by the now narrower breaker, and change the outlet in the room.)

Ah, that sounds like something that I _could_ do, but it's definitely more than I've done before.  I'll try researching it a bit more today but that seems like a "hire someone and watch so I can do it next time" type of job.

Thanks!

[KarefulKactus15]

I might be missing something,  also no dont use a window unit with a wall sleeve.   I mostly linked that article to get a rough calculation that newer 5,000 BTU units pull around 5 amps.

Is there a reason your opposed to simply replacing it with another 220V device?  Your house wiring is already set up for it.    It might be overkill, but I imagine you could run it on a lower setting.     And as little as you plan to use it, the 220v 10,000 btu unit might last forever on low.... lol

It seems alot easier than changing sockets and wires.  Central ACs only have 2 settings, on and off... (unless you have a newer VFD system). That is why load balancing is so important so you dont end up with humidity issues.   

But most of the wall sleeve units I see Have low and Hi modes, so even if you do buy a 10k BTU unit, you dont have to run it at that capacity.

So my final question is,  whats the cost delta from a simple 120V 5,000 BTU unit to a 10,000 BTU 220v unit? (from your research)

[robartsd]

The pic you included only has 3 pins exposed, so you'd need to pull the outlet out and see if it was fed with a 3-conductor (plus ground) or 2-conductor (plus ground). Mostly likely the latter, so you'd have a small amount of work to do on the service panel side as well. (Generally, switch to a single pole breaker, and put one of the now line conductors to the neutral bus bar, blank off the opening left by the now narrower breaker, and change the outlet in the room.)

This sounds right to me. No wires to pull, just changes at the service panel and outlet. Personally I'm comfortable identifying circuits, switching off breakers, and working at the outlet end; but would call in an electrician for a service panel change.

The cost difference between an otherwise identical 120V and 220V units seems to be about $20.  Listed power usage was the same for both as well. Obviously lower BTU ones are a bit cheaper, but 5000 to 10000 BTUs seems to be $100 or so

So you're saying it would cost you about $120 more to purchase a slightly oversized 220V unit. I think that the cost savings on the unit would not be worth the cost of an electrician to me.

[Lagom]

I'll just leave this here :)

http://www.theblaze.com/stories/2013/06/27/can-you-really-beat-the-heat-with-a-20-d-i-y-air-conditioner-we-give-it-a-try/

Haven't tried it yet, but me and the fam are moving into a house with no AC pretty soon. We're in the Bay Area and the house is very well ventilated, so I only expect this to be a problem a few days each year, but I may try one of these myself if it ever gets too uncomfortable! I prefer a version with water frozen in 2 liter bottles, to cut down on mess and wasting water from constantly replacing ice. We're in a drought, after all!

[MilwaukeeStubble]

The cost difference between an otherwise identical 120V and 220V units seems to be about $20.  Listed power usage was the same for both as well. Obviously lower BTU ones are a bit cheaper, but 5000 to 10000 BTUs seems to be $100 or so

So you're saying it would cost you about $120 more to purchase a slightly oversized 220V unit. I think that the cost savings on the unit would not be worth the cost of an electrician to me.

That's what it's looking like.  I'm still worries about going too big for the room but from what people are saying here it looks like that may not be too big of a deal.

Thanks all!

[sokoloff]

The problem with "too big for the load" is the AC will cycle on and off fairly quickly. This is sub-optimal, as you would prefer a longer run-time to dehumidify the air (remove the sensible heat, aka water vapor). (The start/stop is also annoying sound-wise, and may shorten the life of the unit.)

IMO, you want an AC unit that can't quite keep the room down to 75* on the single hottest day of the year. That will get you good comfort and dehumidification throughout the summer. Slightly too small is better than way too big.