Window A/C units? (I'm in the mid-atlantic.)

Curtis said:

If you don't care about your electric bill, multiple small units are the way to go for distribution of the coolness.  A single unit will be more efficient to run.  A single 15k unit doesn't use three times the juice of three 5k units.  If a big single can be put on a shaded side of the house (so it works less and it's not in a hot window) and distributed around the space with a box fan, you'll save a little on the bills.

But what if you don’t need 3 times the cooling?  A big unit uses more energy than a small unit.  At night I only sleep in one room. That’s all that needs cooling. Not the living room or kitchen.  So why should I cool them for the 8 hours or so I’m asleep? And Visa Versa.

mad_machine said:

I feel like the odd one out. Am I the only person in the world to not like AC? 

I think you are definitely the only person on the east coast who doesn't.

The big deal with A/C is definitely the de-humidification.  There's a reason why it's called "Air Conditioning" and not just "Cooling".  One thing to watch is having too much cooling capacity (BTU) can lead to air that is cool, but damp, as the unit hits its temperature bogie quickly, and then kicks off before the benefits of dehumidification can happen.  Then you crank up the unit to cool to a lower temperature, because you're still "warm", thus using more energy than a smaller unit would.  

This is one of the nice things about the mini-splits, at least the ones we got, have a sort of "throttling" capability, so they run a more constant duty cycle but bump up the capacity as the temperature (and humidity) increase.  In fact, last year I tried running them on "dehumidify" only (no cooling) and noticed the room felt comfortable, even at the higher temperature.  

Likewise, in the winter, running a humidifier can help make the room seem more comfortable even at a lower temperature.  We typically cool to about 78 in the summer, and heat to 68 in the winter.  With the minisplits, these are both perfectly comfortable temperatures.  

volvoclearinghouse said:

The big deal with A/C is definitely the de-humidification.  There's a reason why it's called "Air Conditioning" and not just "Cooling".  One thing to watch is having too much cooling capacity (BTU) can lead to air that is cool, but damp, as the unit hits its temperature bogie quickly, and then kicks off before the benefits of dehumidification can happen.  Then you crank up the unit to cool to a lower temperature, because you're still "warm", thus using more energy than a smaller unit would.  

This is one of the nice things about the mini-splits, at least the ones we got, have a sort of "throttling" capability, so they run a more constant duty cycle but bump up the capacity as the temperature (and humidity) increase.  In fact, last year I tried running them on "dehumidify" only (no cooling) and noticed the room felt comfortable, even at the higher temperature.  

Likewise, in the winter, running a humidifier can help make the room seem more comfortable even at a lower temperature.  We typically cool to about 78 in the summer, and heat to 68 in the winter.  With the minisplits, these are both perfectly comfortable temperatures.  

My parents run a dehumidifier in their basement about 7-8 months of the year. Mom said that she noticed that she was able to (A) keep the temperature higher than they used to, and (B) the AC ran less even before they made that adjustment. 

1988RedT2 said:

mad_machine said:

I feel like the odd one out. Am I the only person in the world to not like AC? I personally can't stand the stuff, but then I also wear a pull-over fleece all year round at work because I am always cold there. Unless the temps get into triple digets, I am fine.

Huh?

Here in central Virginia it's the humidity.  I can't even imagine life without A/C.  Food, water? Sure, take it.  No A/C?  Just put a bullet in my head.

I will say this.  Many people I know, and most businesses as well, will heat to maybe 70 in the Winter, but come Summertime, that thermostat will be down to 65 and it'll be like a freaking icebox.  Drives me crazy.  I cool to around 75.  With the low humidity, it feels fine.  If I get hot, I take off clothing.

If I were to climb up onto my roof, I would be able to see the Atlantic Ocean, The Back Bay is literally at the end of my street. Humidity is a way of life here in on the Southern Jersey Shore.

frenchyd said:

Curtis said:

If you don't care about your electric bill, multiple small units are the way to go for distribution of the coolness.  A single unit will be more efficient to run.  A single 15k unit doesn't use three times the juice of three 5k units.  If a big single can be put on a shaded side of the house (so it works less and it's not in a hot window) and distributed around the space with a box fan, you'll save a little on the bills.

But what if you don’t need 3 times the cooling?  A big unit uses more energy than a small unit.  At night I only sleep in one room. That’s all that needs cooling. Not the living room or kitchen.  So why should I cool them for the 8 hours or so I’m asleep? And Visa Versa.

 

 

I see your point.  The way I did it was to put the big A/C in the bedroom.  That way it only cools the bedroom at night with the door closed.  A huge A/C will use more than a single small one in the bedroom to accomplish the same thing, but overall I think it will be electrically beneficial to do fewer/bigger units.

If he needs a total of 15k (for example) I could see shooting the middle and doing a 10k for the living area and a 5k for the bedroom.  Still better than three 5k units.

In reply to mad_machine :

Ah, you're in Joisey.  I'm from Joisey!  Born and raised.  Yah, we never had A/C when I was a kid.  But it just doesn't get that hot in Joisey.  And you've got those lovely ocean breezes. 

mad_machine said:

I feel like the odd one out. Am I the only person in the world to not like AC? I personally can't stand the stuff, but then I also wear a pull-over fleece all year round at work because I am always cold there. Unless the temps get into triple digets, I am fine.

We very seldom get heat and humidity at the same time here unless there is a storm that comes up  from Mexico ,

We can have fog in the morning  and 85f in the afternoon , but not humid , 

I just got back from vacation where it was hot and humid , I set room air at 80F  so it was not às much of a shock going out the front door and it was 93F and 85 percent humidity, 

But the 7-11 would be at 70F or less and always a shock to walk into , get a drink and then outside at 95F

I think it’s a riot when Northerners debate and discuss AC. There is not a single Southerner in this thread. 

The correct answer is it’s about cooling load and humidity, guys. That and the delta to the ambient exterior. 

Lots of incorrect information in this thread, but it doesn’t really matter. The answers in this thread are good ones for Northerners, and the OP is a Northerner, so I’ll leave it alone. 

Yes, multiple window units will serve your needs quite adequately. 

One note...

Interior walls are not insulated. That means you are not really compartmentalizing when you close doors. 

But thermal mass also matters. 

I suspect several of you live in older plaster walled houses. An uninsulated plaster wall will resist thermal conductivity better than a newer drywall wall. 

So yes. Smaller units work great in the North (where there is less load), and also do a better job in older houses. 

I've read it's somewhat unhealthy to "shock" your body, either going from a 74 degree heated place into single digit temps, or going from 102 degrees into a meat locker.  Not to mention the energy used to try to maintain those temperatures.  

Air Conditioning is good at dehumidification, and dropping the temps 20-25 degrees.  Asking it to do more than that is going to spike your power bills and wear out your equipment. 

SVreX said:

One note...

Interior walls are not insulated. That means you are not really compartmentalizing when you close doors. 

But thermal mass also matters. 

I suspect several of you live in older plaster walled houses. An uninsulated plaster wall will resist thermal conductivity better than a newer drywall wall. 

So yes. Smaller units work great in the North (where there is less load), and also do a better job in older houses. 

I understand your background is related to this field, so I respect your input.  And the fact that you live in a warmer climate.

However, my experience suggests that, even though interior walls are not insulated, closing off sections of a building can concentrate heating/ air conditioning so as to make the use of a smaller unit effective for just maintaining a certain temperature in that room.

For example, in our bedroom, we keep the mini split set to 72 in the summertime, for sleeping.  On a day that might be 85 to 90 degrees, with 75% or higher humidity (this is the mid-atlantic we're talking about) the hallway immediately outside the bedroom will be noticeably warmer (our downstairs is not air conditioned at all).  

Heat moves via three modes: conduction, convection, and radiation.  Closing off a room eliminates the second mode, which is usually the most significant contributor to heat transfer.  

SVreX said:

I think it’s a riot when Northerners debate and discuss AC. There is not a single Southerner in this thread. 

 

We don't debate A/C in the South. We just discuss how much you need. My first house had a 24k btu window unit in the living room and a 8k btu unit in the master bedroom. The house was basically a big circle so a box fan was used to disperse the cool air through the rest of the house. Those units ran hard from mid July through late August. 

As much as I would love multiple small units and no central system, I'm more likely to consider a smaller central system, sized for the majority of the year and supplemental units for the worst part of the summer. My house is actually more comfortable in July and August than it is in April and May because during the spring and fall it doesn't run enough to dehumidify the house. For the months of July and August, the unit never shuts down. Even at night. 

What will probably happen is either 4 tons of multi-split or a 3-4 ton variable speed unit. That will probably happen in the next couple of years. My current unit is 15 years old. 

Here’s how I did AC in Connecticut.  I went to Costco and bought a $100 window unit. When I needed more, I bought another one. When I moved, I sold them for basically the same price as I paid for them.  When one of them broke two years on, I returned it to Costco for another one.  

volvoclearinghouse said:

I've read it's somewhat unhealthy to "shock" your body, either going from a 74 degree heated place into single digit temps, or going from 102 degrees into a meat locker.  Not to mention the energy used to try to maintain those temperatures.  

Air Conditioning is good at dehumidification, and dropping the temps 20-25 degrees.  Asking it to do more than that is going to spike your power bills and wear out your equipment. 

Well we long lived Minnesotains go from nice warm homes and work places to our cars in 20-30 below weather.  Some wacko’s even cut holes in the ice and dive into frozen lakes. 

And from our cool 65 degree homes out into the 100 degree with 90% humidity summer

SVreX said:

One note...

Interior walls are not insulated. That means you are not really compartmentalizing when you close doors. 

I suspect several of you live in older plaster walled houses. An uninsulated plaster wall will resist thermal conductivity better than a newer drywall wall. 

So yes. Smaller units work great in the North (where there is less load), and also do a better job in older houses. 

Sure you are compartmentalizing. It isn't as efficient as if they'd been insulated, but it is still making it a much better situation. 

As for "work in the North", when I had mine in the house, I put them in because we had a 5 day forecast of over 100*. The two <5000btu units worked so well that the central AC didn't kick in at all until I removed them.  

You guys speak about 'the north' like its so much cooler than 'the south'.  In the hottest months the difference is small.  Chicago averages in the summer are a couple degrees lower and a couple points less humid.  Obviously the summer is much shorter there.

Its nothing like the winter where there is a 30 or 50 degree difference.

ProDarwin said:

You guys speak about 'the north' like its so much cooler than 'the south'.  In the hottest months the difference is small.  Chicago averages in the summer are a couple degrees lower and a couple points less humid.  Obviously the summer is much shorter there.

Its nothing like the winter where there is a 30 or 50 degree difference.

And many times it is much more humid, thanks to that thing called "Lake Michigan"

I should mention my very first summer and new apartment was without a/c.  Worked for Marriott at maybe $7 something an hour.  Only had a ceiling fan in the bedroom and thank the good lord I even had that. I was miserable especially as I had to take baths - they wouldn't put in a shower but it was $435 20 yrs ago.  It probably rents north of $1,200 now if not considerably more being close to the subway. 

All good advice so far and I think I'll go the multiple 5k route.  Still to be decided.  Thanks guys. 

Fueled by Caffeine said:

Here’s how I did AC in Connecticut.  I went to Costco and bought a $100 window unit. When I needed more, I bought another one. When I moved, I sold them for basically the same price as I paid for them.  When one of them broke two years on, I returned it to Costco for another one.  

my googlefu could be foo'd but those days appear to be gone. 

https://www.costco.com/air-conditioners.html

Fueled by Caffeine said:

Here’s how I did AC in Connecticut.  I went to Costco and bought a $100 window unit. When I needed more, I bought another one. When I moved, I sold them for basically the same price as I paid for them.  When one of them broke two years on, I returned it to Costco for another one.  

And this is the correct answer for many of you with older homes.  It's what I did with my first home, a tri-level built in 1960, with baseboard electric heat and no central A/C.   Thoes with fairly deep pockets could consider retrofitting a central system into an older home.  I would think that any house south of the Mason-Dixon line built in the last 30 years would have a central heating-cooling system.

Costco does not in fact trumpet the fact that they sell window A/C units online, but if you venture into one of their stores, you will find them, I promise.  And 100 bucks is where you can usually find the 5k BTU units.

Or you can shop at Wally-World:

https://www.walmart.com/ip/Cool-Living-5-000-BTU-Window-Air-Conditioner-115V-With-Window-Kit/

mtn said:

ProDarwin said:

You guys speak about 'the north' like its so much cooler than 'the south'.  In the hottest months the difference is small.  Chicago averages in the summer are a couple degrees lower and a couple points less humid.  Obviously the summer is much shorter there.

Its nothing like the winter where there is a 30 or 50 degree difference.

And many times it is much more humid, thanks to that thing called "Lake Michigan"

Minnesota has Lake Superior plus about another 15,000 lakes. We are the source of three great Rivers .  Mississippi,  Going  to the Gulf of Mexico, Red River of the North, going to Hudson’s  Bay and  St. Louis River Going to the Great Lakes and ultimately the Atlantic Ocean. 

I’ll put our summer humidity up against nearly anyone’s. OK, you win Florida. 

Costco doesn't have the window units online, and probably won't have them in the stores for another few weeks. 

In reply to 1988RedT2 :

thanks for the info.

volvoclearinghouse said:

SVreX said:

One note...

Interior walls are not insulated. That means you are not really compartmentalizing when you close doors. 

But thermal mass also matters. 

I suspect several of you live in older plaster walled houses. An uninsulated plaster wall will resist thermal conductivity better than a newer drywall wall. 

So yes. Smaller units work great in the North (where there is less load), and also do a better job in older houses. 

I understand your background is related to this field, so I respect your input.  And the fact that you live in a warmer climate.

However, my experience suggests that, even though interior walls are not insulated, closing off sections of a building can concentrate heating/ air conditioning so as to make the use of a smaller unit effective for just maintaining a certain temperature in that room.

For example, in our bedroom, we keep the mini split set to 72 in the summertime, for sleeping.  On a day that might be 85 to 90 degrees, with 75% or higher humidity (this is the mid-atlantic we're talking about) the hallway immediately outside the bedroom will be noticeably warmer (our downstairs is not air conditioned at all).  

Heat moves via three modes: conduction, convection, and radiation.  Closing off a room eliminates the second mode, which is usually the most significant contributor to heat transfer.  

 

You and I agree completely..  closing off a room reduces convection, and therefore has a great deal of effectiveness. 

But effectiveness and efficiency are not the same thing. 

I have no problem with small window units in a Northern house. It’s quite effective. 

But it is not efficient. The conduction thermal loss to adjoining spaces is pretty significant. 

I can put a window AC unit in an uninsulated garage and leave the doors open. Standing in front of it is still effective, but definitely not efficient. 

A well insulated house is a different story. The thermal envelope is utterly important, and maintaining equal temperatures throughout the enclosed space whike minimizing transfer or loss to outside the envelope requires very little energy. But it has to be centralized. That’s efficiency.