AC during a heat wave

[GrayHare]

With the TD (outdoor - indoor) temp being an important number for heat transfer, I decided to bump up the indoor by 1 degree during the hottest part of the day,.

 

[jollystomper]

We tend to keep the temperature at 76 when it gets very hot. If one is in and out enough, it feels very cool. Our basement also stays cool, around 72. The heat pump also does a good job of keeping the humidity low.

Our bedroom on the upper floor will run a 1-2 degrees warmer, but we just bought a portable AC unit (I got lazy and decided to not wrestle with a window AC this year) we use in the evening, and it does a good job of setting the temperature down to around 73, which is where DW likes it at night.

 

[disneysteve]

We’re in the midst of the heat dome. We’ve reached that lovely point where the AC is at its limit and can’t actually achieve the set point. It can only do at most 30 degrees from outside temp. With it over 100° outside even though we have it set at 70 it’s 72 in the living room where the thermostat is and probably at least 5° warmer upstairs.

Thankfully it will be under 100 tomorrow and under 90 by Sunday.

 

[skipro33]

We’re in the midst of the heat dome. We’ve reached that lovely point where the AC is at its limit and can’t actually achieve the set point. It can only do at most 30 degrees from outside temp. With it over 100° outside even though we have it set at 70 it’s 72 in the living room where the thermostat is and probably at least 5° warmer upstairs.

Thankfully it will be under 100 tomorrow and under 90 by Sunday.

At 72 indoors, I'd need a freaking sweater! Ha!
Put a mister on your condenser (outside A/C unit). That will pre chill the air from 100 degrees by several degrees.

 

[Gumby]

We have no central a/c, just two window units - one in the bedroom and one for the kitchen, office, and sewing room, which is where we spend the majority of our time in the summer. Usually, we turn on the bedroom unit shortly before bedtime and turn off the downstairs. We open all the windows (except the BR) at bedtime and close them and draw the shades in the morning. Then switch the running a/c unit.

We are investigating getting central air, but our 169 year old house has radiators for heating and hence no ducts and no room for ductwork. We're also in the historic district, so we can't alter the exterior of the house. We've heard of high pressure microduct systems and will consult with a contractor who has been recommended to us this fall (I'm sure they're busy right now).

 

[DrRoy]

We have ours set at 75 in the day when we are at home. If we go out for hours I'll raise it to 78 .
At night we lower it to 73.

Our central air seems to fail during heat waves, it's been the condenser two times. I have a spare now, but still hate changing it when the temp is 95 F.

We set ours the same. Haven’t had any failures on our system from 2008.

 

[MC Rider]

Our AC works well, but is > 20 yo and I'll guess not so efficient. In 2024 we got a couple electric bills in hot moths for $600. Holy yikes! We also have 2 evaps on the roof and it's a dry heat, so those do pretty well. We try not to use the HVAC in summer unless we need to.

 

[Midpack]

In Summer our thermostat is set at 74°F from 5am to 8pm, then 71°F overnight - we can’t sleep if we’re not cool. Fortunately the AC doesn’t have to work very hard at night when outside temps are (much) lower than daytime. And we use ceiling and floor fans, which makes a BIG difference!

I’d rather keep our outside temp vs thermostat differential under 20°F, and it is most weeks, but unfortunately it’s been above that here lately.

 

[Jerry1]

I’ve kind of settled in on 76 degrees. Letting it go to 80 wasn’t pleasant or worth it so I’m trying to find how much lower I need to go to be comfortable without going too low and having the AC run continuously. Yesterday and Wednesday the unit ran about 10.5 hours. Those were our hottest days. We’ll be down into the 80’s soon.

 

[Walt34]

We like the house warmer than most people and only turn it down to 78° at night, summer and winter. We'll let the temperature drift upward to 81 or 82 during the day (83 if DW isn't home) during the summer and a few degree less than that in the winter. When we contracted for the house one of the options was an "extra insulation package" and they didn't skimp on that so our utilities are not outlandish, in fact they're lower than most of our relatives. The lower price of natural gas helps too. And I figure that what we spend in the winter we save in the summer.

Lesson learned: Gobs of insulation makes a huge difference!

 

[audreyh1]

At 72 indoors, I'd need a freaking sweater! Ha!

Same here!

We do wear very light clothing during our summer - our six month long summer, ha ha.

 

[NW-Bound]

We are investigating getting central air, but our 169 year old house has radiators for heating and hence no ducts and no room for ductwork. We're also in the historic district, so we can't alter the exterior of the house. We've heard of high pressure microduct systems and will consult with a contractor who has been recommended to us this fall (I'm sure they're busy right now).

It should be possible to install mini-splits with refrigerant lines running under the crawl space or basement. It takes up more spaces inside the room for the indoor units, compared to the microducts. But perhaps the radiators can be removed and the heating handled by the new minisplits for even less space occupied by the equipment.

 

[Gumby]

It should be possible to install mini-splits with refrigerant lines running under the crawl space or basement. It takes up more spaces inside the room for the indoor units, compared to the microducts. But perhaps the radiators can be removed and the heating handled by the new minisplits for even less space occupied by the equipment.

The walls will not support mini-splits as it is post and beam construction with plaster and lath.

 

[Chuckanut]

I use 74-76 as a comfortable range when I need the AC. In the evening when the temp falls below this area I use a window fan to circulate cooler outside air into the room. I cools two rooms, the master bedroom and the living area. That’s enough for me to be comfortable.

 

[Jerry1]

Well, it doesn’t matter now. We just had a storm blow through and about 300K people are without power. My generator will keep me comfortable in most ways, but it won’t run my AC. So, I guess I’ll be running whatever temp Mother Nature has to offer for a while. Storms like this usually take a few days to get everyone back on line. Just a matter of when they get to my area on how long it will be.

 

[disneysteve]

Well, it doesn’t matter now. We just had a storm blow through and about 300K people are without power. My generator will keep me comfortable in most ways, but it won’t run my AC. So, I guess I’ll be running whatever temp Mother Nature has to offer for a while. Storms like this usually take a few days to get everyone back on line. Just a matter of when they get to my area on how long it will be.

If our power goes out, we pack bags and go to a hotel. No way we would stay in the house without AC. Or without heat in the winter. We have evacuated to hotels a number of times over the years for just that reason.

 

[ERD50]

We've never tried to save money by cutting back on heating or air conditioning. In general, cooling is more difficult to achieve and usually costs more than heating.

During the summer, we keep the thermostat at 74°F during the day and 71°F at night. In the winter, we set it to 78°F during the day and 73°F at night. In the summer the AC works many hours daily. ...

Help me understand this, you say cooling is more difficult to achieve and more $$ (and I agree with that, for most cases) - yet, you keep at at 74/71 in the SUMMER, and 78/73 in the WINTER?

In the summer, I wear shorts and a t-shirt and barefoot in the house most of the time. I'm comfortable @ 77F.

In the winter, I wear socks/slippers, long pants and a sweatshirt. I can be comfortable @ 64/66 if I'm active, but rarely turn it above 70.

Why would you have it set colder in summer than winter?

 

[MC Rider]

Well, it doesn’t matter now. We just had a storm blow through and about 300K people are without power. My generator will keep me comfortable in most ways, but it won’t run my AC. So, I guess I’ll be running whatever temp Mother Nature has to offer for a while. Storms like this usually take a few days to get everyone back on line. Just a matter of when they get to my area on how long it will be.

If Genny kept my beer cold and my ice cream hard, I think I'd be happy.
Is it 867-5309?

 

[Jerry1]

If Genny kept my beer cold and my ice cream hard, I think I'd be happy.
Is it 867-5309?

Not 867-5309, but I can keep my fridge and an upright freezer running. Also have lights and internet. Not too bad. Losing power in the winter is much worse.

As for going to a hotel, I’m just not built that way. When there’s difficulties at home, I hunker down. We’ll be inconvenienced but we’ll be fine.

 

[kgtest]

69 to 71 in winter unless vacation mode, then it's 55.

69 to 71 in summer, with windows open unless its above 75 to 80 or super humid.

 

[Teacher Terry]

It appears in more of the cases where the AC is set in the low 70's, it is more favored by women. I would have guessed the opposite.

When most women go through menopause they often feel like someone lit a fire inside their body! It’s definitely not fun. Some women end up permanently hot unfortunately from menopause. I think that explains the difference.

 

[FD1000]

Help me understand this, you say cooling is more difficult to achieve and more $$ (and I agree with that, for most cases) - yet, you keep at at 74/71 in the SUMMER, and 78/73 in the WINTER?

In the summer, I wear shorts and a t-shirt and barefoot in the house most of the time. I'm comfortable @ 77F.

In the winter, I wear socks/slippers, long pants and a sweatshirt. I can be comfortable @ 64/66 if I'm active, but rarely turn it above 70.

Why would you have it set colder in summer than winter?

I don't know many men who are comfortable when it's 77°F indoors during the summer, and I don't know many women who aren't cold when it's 64–66°F. There are always exceptions.

In the summer, we keep our thermostat between 71–74°F. In the winter, it's set to 68°F during the day and 63°F at night. I also just replaced the thermostats on both floors of the house.

 

[RetiredHappy]

When most women go through menopause they often feel like someone lit a fire inside their body! It’s definitely not fun. Some women end up permanently hot unfortunately from menopause. I think that explains the difference.

I guess I am fortunate because I have never experienced hot flashes. I prefer to sleep at 74 to 75 degrees F, whereas my husband prefers 70 to 71. I add an extra layer of blanket on my side of the bed. However, in winter, I can tolerate freezing temperature very well, and have no problem golfing when it is cold, and one time when it was snowing here in the middle of the round. I usually get by with just my long sleeve golf shirt during winter, and at most, another light jacket. My husband cannot stand winter cold, and ditched me one time in Monterey and headed back to the club house while I continued and finished my round. He cancelled golf the rest of the trip.

 

[Teacher Terry]

I guess I am fortunate because I have never experienced hot flashes. I prefer to sleep at 74 to 75 degrees F, whereas my husband prefers 70 to 71. I add an extra layer of blanket on my side of the bed. However, in winter, I can tolerate freezing temperature very well, and have no problem golfing when it is cold, and one time when it was snowing here in the middle of the round. I usually get by with just my long sleeve golf shirt during winter, and at most, another light jacket. My husband cannot stand winter cold, and ditched me one time in Monterey and headed back to the club house while I continued and finished my round. He cancelled golf the rest of the trip.

I had a brutal menopause and it was awful. I wore at work a button-down sweater with a tank top underneath so when I would get really hot, I could just take off the sweater. The problem is you’re not hot all the time but all of a sudden you start excessively sweating and then when you cool down, you’re wet and cold. I had the grate closed in my office in the winter so I wouldn’t get heat and cardboard taped over it and a big fan in my doorway.

At home, I was living with my husband, stepson, and two of my three sons were going to college. If anybody dare whined about being cold, I yelled at them to put on a coat). To give you an idea how bad it was I sometimes would step outside when it was extremely cold in a tank top and shorts.

Everyone including my friends, learned to dress warm in the winter when they came over and they still tease me about it. Unfortunately, menopause was a long journey, but it’s over now.

 

[FIREd]

I live in Europe and don’t have A/C.

During the latest heatwave, when temperature reached close to 100F, I managed to keep the temperature inside my concrete-built city condo below 84F (open all the windows in the early morning to cool down and close all the shutters during the hottest part of the day, to prevent the heat from coming in etc…). With low relative humidity, it was comfortable enough - particularly when using a fan during the hot afternoons. The problem is that concrete retains heat and the indoor temperature rarely dropped below 80F at night, which is a bit hot for me to sleep comfortably, even with a fan.

My stick-built cabin in the mountains on the other hand had much more indoor temperature variations. I kept the windows open day and night. In the afternoon, indoor temperature would reach almost 90F (I didn’t care as I spent the day outside in the shade enjoying the natural mountain breeze), but the indoor temperature would drop promptly to the low 70s after sunset, even reaching the 60s overnight which is perfect for sleeping. Having the ability to escape heatwaves was one of my primary motivations to build the cabin and this heatwave was my first opportunity to test the cabin in hot weather. I am very pleased.

That said, I remember the muggy summers in the southeastern US and I used to keep the A/C at 72-75F. 80F would have been unbearable.