Hot Topic in my household - temperature control during the day?

[eyePod]

We live in MD. Temps are warm and the humidity is high. we have an original (but maintained) HVAC from 1989. We have manual controls.

I have a super pregnant wife too.

Big question, is it worth it for us to have the temp set at 77-78 during the day when we aren't home and then re-adjust to the comfortable 75 for the evenings? An hvax technician told my wife that it wasn't worth it because the system is so old but all we were given was qualitative "its not worth it."

Any help would be awesome! And it's hard to do the experiment ourselves with the lagging indicators and a sensitive pregnant wife.

[antdunh]

We live in CT, I also have a pregger wife.  We keep just the upstairs Ac at 78-80 during the day then turn it down.  However, we were able to switch our electric provider at the right time and pay less than half what the current generation rate is.  I would say it is mostly cost driven.  I have noticed approx. $10-20 more per month on electric with this method, but I feel like it keeps a lot of the humidity out of the house without wasting too much power. I don't mind spending money on comfort, especially to keep a pregger wife from melting.

[GuitarStv]

Turn your HVAC off during the day, and then back on when you come home.  Your AC doesn't use electricity when it's off.  Your house gains less heat during the day the closer internal temperature reaches external temperature (close all shades and window coverings on the south, east, and west sides of your home in the morning).  Your AC will slowly return your home to cooler temperatures after you get home, and you will save money for the energy that you didn't waste during the day.

[boarder42]

why do you need AC below 78 degrees at any time? 

[Jack]

The cost of heat or AC is directly proportional to the integral over time of the temperature difference that it's trying to maintain. The lower the temperature difference, the less energy it uses. I can only assume that the HVAC guy told your wife "it's not worth it" because you were only talking about a 2-degree change, which would save, but only a little bit.

We have manual controls.

Except for fancy shit like the Nest, programmable thermostats are cheap. Get one, install it yourself, then set it to turn off¹ during the day and go back down to the comfortable temperature² a little bit before you get home, such that it actually reaches the target temp as you arrive.

¹ By "off" I mean the highest temperature that doesn't allow mold growth or damage anything, which my or may not be literally "off"

² Except for the "very pregnant wife" part, this should be higher than 75 degrees -- I suggest something in the 78-82 range. If that's too hot, wear fewer clothes.

[eyePod]

why do you need AC below 78 degrees at any time?

Pregnant wife is number 1.
We live in a 3 story townhome, and the third floor is at least 10 degrees cooler. We have a fan in our bedroom and use fans throughout the house but its just not enough since it doesn't get cool until past 9pm when we are already on our way up to bed.

[eyePod]

The cost of heat or AC is directly proportional to the integral over time of the temperature difference that it's trying to maintain. The lower the temperature difference, the less energy it uses. I can only assume that the HVAC guy told your wife "it's not worth it" because you were only talking about a 2-degree change, which would save, but only a little bit.

We have manual controls.

Except for fancy shit like the Nest, programmable thermostats are cheap. Get one, install it yourself, then set it to turn off¹ during the day and go back down to the comfortable temperature² a little bit before you get home, such that it actually reaches the target temp as you arrive.

¹ By "off" I mean the highest temperature that doesn't allow mold growth or damage anything, which my or may not be literally "off"

² Except for the "very pregnant wife" part, this should be higher than 75 degrees -- I suggest something in the 78-82 range. If that's too hot, wear fewer clothes.

The current thermostat is electrically wired so I'm not sure how I can replace it. We just got a new one since the older one was on the fritz. It was replaced through our home warranty.

We will be getting the HVAC replaced in the next few years so I think we can manage with the manual controls for now.

The nice thing is that our downstairs is super comfortable with our hard wood, a fan, and bare feet

[Scandium]

Depending on where in MD, BGE has an energy saving program where they will cycle your ac off on peak days, and give you cash for it. But if you sign up they will also install a programmable thermostat for free. At least when I did it years ago.

I'm fine with 80 many situations, but when the humidity is high and/or I'm getting ready for work I need it lower. Plus my wife dislike it more than I do. Fans are great and all, but when you're blowing moist, sweaty sauna air into your house as you're trying to sleep I say fuck it and turn on the AC. Way cheaper than the heating season anyway.

[Kitsune]

why do you need AC below 78 degrees at any time?

Because being pregnant and hot and sticky in summer SUCKS, and if my non-pregnant husband had tried to tell me that a 30$ difference on the electric bill was worth being overly hot and sticky IN ADDITION to the other discomforts of pregnancy (shooting pain in my hips, constant nausea, etc), I would have cheerfully strangled him. So: I sympathize with the OP's wife.

TL;DR: for his health and his marriage.

[mskyle]

The current thermostat is electrically wired so I'm not sure how I can replace it. We just got a new one since the older one was on the fritz. It was replaced through our home warranty.

We will be getting the HVAC replaced in the next few years so I think we can manage with the manual controls for now.

The nice thing is that our downstairs is super comfortable with our hard wood, a fan, and bare feet

It's so easy to change a thermostat, though, and so worth it! There are videos on YouTube for it. I changed out the thermostat in my (rental) apartment for a wi-fi enabled one. The thermostat was $99 on Amazon and I got a rebate for the full amount from the gas company (they would reimburse up to $100). It took my boyfriend and I about an hour to install it plus a trip to the hardware store, and that was only because one of the wires had not previously been attached at the furnace. If all the wires were already connected at the furnace end, it would have seriously take 15 minutes (it would be easy to check if this is the case for you - pop the faceplate off and have a look).

I love my thermostat. It was a game-changer. And then you can very easily keep your thermostat at 78 during the day and have it be at a temperature that's comfortable for you both by the time you get home.

[Jack]

We live in a 3 story townhome, and the third floor is at least 10 degrees cooler. We have a fan in our bedroom and use fans throughout the house but its just not enough since it doesn't get cool until past 9pm when we are already on our way up to bed.

That's weird; usually the top floor is the hottest. Is your HVAC system in the attic?

At any rate, try closing the vents in the coldest areas to balance the airflow.

We have manual controls.

Except for fancy shit like the Nest, programmable thermostats are cheap. Get one, install it yourself...

The current thermostat is electrically wired so I'm not sure how I can replace it. We just got a new one since the older one was on the fritz. It was replaced through our home warranty.

You shut your AC & furnace off at the breaker / switch, remove the thermostat from the wall, unscrew the wires from the back, screw them to the new thermostat, and mount the new thermostat on the wall.

It's barely any harder than changing a lightbulb; the only thing even slightly complicated about it is matching up the wires correctly. No big deal if you can follow instructions.

We will be getting the HVAC replaced in the next few years so I think we can manage with the manual controls for now.

This one is $25 and perfectly decent (it's the same kind I have, in fact). Even if you are getting a new system in the next few years it's still worth it to upgrade the thermostat now, because the payback period will probably be less than a year.

(Also, as other people reminded me, sometimes you can get one for free -- so there's really no excuse not to do it.)

[mtn]

why do you need AC below 78 degrees at any time?

Because I'm sweating at 73. Have been like that my whole life. If it wasn't for my guitars, I'd probably keep my house in the winter at about 58*.

Ok, I'm exaggerating. 60*, after that I'd have to put on pants.

[eyePod]

We live in a 3 story townhome, and the third floor is at least 10 degrees cooler. We have a fan in our bedroom and use fans throughout the house but its just not enough since it doesn't get cool until past 9pm when we are already on our way up to bed.

That's weird; usually the top floor is the hottest. Is your HVAC system in the attic?

At any rate, try closing the vents in the coldest areas to balance the airflow.

We have manual controls.

Except for fancy shit like the Nest, programmable thermostats are cheap. Get one, install it yourself...

The current thermostat is electrically wired so I'm not sure how I can replace it. We just got a new one since the older one was on the fritz. It was replaced through our home warranty.

You shut your AC & furnace off at the breaker / switch, remove the thermostat from the wall, unscrew the wires from the back, screw them to the new thermostat, and mount the new thermostat on the wall.

It's barely any harder than changing a lightbulb; the only thing even slightly complicated about it is matching up the wires correctly. No big deal if you can follow instructions.

We will be getting the HVAC replaced in the next few years so I think we can manage with the manual controls for now.

This one is $25 and perfectly decent (it's the same kind I have, in fact). Even if you are getting a new system in the next few years it's still worth it to upgrade the thermostat now, because the payback period will probably be less than a year.

(Also, as other people reminded me, sometimes you can get one for free -- so there's really no excuse not to do it.)

I meant hottest! We have all vents closed on both of the bottom floors.

[AZDude]

Maybe get a small room air conditioner for just the upstairs? Probably less electricity used.

[boarder42]

why do you need AC below 78 degrees at any time?

Because I'm sweating at 73. Have been like that my whole life. If it wasn't for my guitars, I'd probably keep my house in the winter at about 58*.

Ok, I'm exaggerating. 60*, after that I'd have to put on pants.

your body adjusts naturally to temperature ... its pretty amazing what it can do... adjust your body and you'll save bundles each season.  either that or lose weight may help . 

[I'm a red panda]

why do you need AC below 78 degrees at any time?

Because being pregnant and hot and sticky in summer SUCKS, and if my non-pregnant husband had tried to tell me that a 30$ difference on the electric bill was worth being overly hot and sticky IN ADDITION to the other discomforts of pregnancy (shooting pain in my hips, constant nausea, etc), I would have cheerfully strangled him. So: I sympathize with the OP's wife.

TL;DR: for his health and his marriage.

Excellent response!

I'm actually the one who is a stickler about the temperature not going below 78. (We keep it at 82 when we aren't home, 80 when we are, and lower it only if it is really miserable.)

Now, pregnant- I've actually gotten it up and set it to 77 a few times.


I would raise it when no-one is home, if that is a full workday. I wouldn't raise and lower it if you are  gone for an hour or so.  I highly recommend a programmable thermostat.

[bogart]

My understanding is that unless your system has an "urgent" feature that is high-energy-consumption and kicks in if there is a big difference between where you want the temperature to be, and where it is, it is *always* cheaper/uses less energy to limit the time you are trying to cool (or heat) your home. 

I wouldn't consider a 1989 system "old," certainly not too old to have that feature, so maybe worth checking, but unless it's there, sure, I'd let the temp go up except when you (or DW) need it down to be comfortable.

My DH is very definitely not pregnant, but cannot sleep nights unless the temp in the house is no more than 76, maybe 74.  Would that this were not so, but it is (unlike your HVAC, he is "older," so that may be a factor.  Nice, as several commenters have suggested, to imagine that all our bodies work well forever but in fact, not all do, and even those that have, seem to do less so as we age).

Congratulations on the expected arrival!

[mtn]

why do you need AC below 78 degrees at any time?

Because I'm sweating at 73. Have been like that my whole life. If it wasn't for my guitars, I'd probably keep my house in the winter at about 58*.

Ok, I'm exaggerating. 60*, after that I'd have to put on pants.

your body adjusts naturally to temperature ... its pretty amazing what it can do... adjust your body and you'll save bundles each season.  either that or lose weight may help .

Yeah, it does adjust naturally. But that doesn't mean that I'm comfortable.  I've been this way my whole life, even when I was a stick. I could lose weight now, will still be a radiator. I get checked for a thyroid issue every time I go to the doctor, but I'm fine.

If I'm inside with AC, it will be at 73, or a fan will be blowing on me because otherwise I sweat through my shirts and underwear, even with gold-bond. And like I said, in the winter I'm happy at 60 degrees inside (but my guitars are not). I play hockey, I'm decsended from nordic climates, I vacation where I can see the northern lights. I like the cooler temperatures.

[mandy_2002]

We will be getting the HVAC replaced in the next few years so I think we can manage with the manual controls for now.

This one is $25 and perfectly decent (it's the same kind I have, in fact). Even if you are getting a new system in the next few years it's still worth it to upgrade the thermostat now, because the payback period will probably be less than a year.

(Also, as other people reminded me, sometimes you can get one for free -- so there's really no excuse not to do it.)

This is the same thermostat that I installed into my 1960's home.  I'm not super handy, but it was something like 4 wires that needed to be put in the correct place, which were marked the same in the 35 year old thermostat.  The most difficult thing I had to do was figure out placement to hide the missing wallpaper areas caused by the transition from a circular to rectangular unit.

[Rural]

I recommend determining what the pregnant person would like for it to be set at when she is there, then acquiring a programmable thermostat and programming it so that the house will be back to the chosen temperature when she arrives. Then you can rise it when no one is home, and there will be both frugality and some justice in the world.