My thermostat and DST - a burning question with only one right answer

[boomerang]

I have a Wifi thermostat at my winter residence in Florida. I have it scheduled to turn on the A/C two hours before dawn. About once a month, I use an app on my phone to change that time to be in sync with the change in the time the sun rises.

Although I can change the time the A/C turns on in the schedule, I cannot change the time of day on the thermostat. I have to physically be in front of it to do so.

Do I need to change the time the A/C comes on to compensate for the time change associated with the change from DST?

My wife, a friend and I are going round and round on this. It should be simple but we are overthinking it. Once we convince each other that it has to be approached one way, we think about it a bit and start changing our thinking.

What says OT?

 

[lxskllr]

Do I need to change the time the A/C comes on to compensate for the time change associated with the change from DST?

No. It'll work the same Monday as it did Friday. You'll have to account for the time offset when making adjustments til you can set it properly.

Edit:
Above is assuming the thermostat doesn't set itself using the network. Strange oversight if so, but not out of the realm of possibility. If it sets itself, you'll have to change the time by 1 hour.

 

[boomerang]

No. It'll work the same Monday as it did Friday. You'll have to account for the time offset when making adjustments til you can set it properly.

I think you just contradicted yourself.

Just saw your edit. No, there is no means for the thermostat to alter its time through the network.

The fun is starting.

 

[disappoint]

Do I need to change the time the A/C comes on to compensate for the time change associated with the change from DST?

Yes.

 

[DaTT]

Why do you run it once a month? Why not just turn it on when you get there...or just before if you can do so remotely?

But I would imagine the thermostat's clock will change itself if it's on a network.

 

[lxskllr]

I think you just contradicted yourself.

No. You're bumping the time to stay in sync with the sun. Unless you're making daily changes, it'll be close enough to the same tomorrow as it was Friday. That's assuming it doesn't set its own time per my edit.

Edit:
What I mean by accounting for time offset is you can't use your watch anymore. Friday you were on the same time system as your thermostat. You're not the same anymore, but it'll turn on tomorrow at the 'same' sun position as it did Friday.

 

[boomerang]

Why do you run it once a month?

You've either misread my post or I wasn't clear enough which is entirely possible. I only change the time the A/C comes on monthly. Sunrise only changes about 15 minutes a month.

In Florida, it's important to have the A/C running to keep mold from growing. There is more to it than that, but that should be good enough for the purposes of my question.

 

[boomerang]

No. You're bumping the time to stay in sync with the sun. Unless you're making daily changes, it'll be close enough to the same tomorrow as it was Friday. That's assuming it doesn't set its own time per my edit.

I'm not arguing although I am aware that I sometimes come across that way. Keep that in mind.

Let's use an actual time and a reference time. Because the sunrise hasn't changed, the time has. (We're not worried about the tiny amount the sunrise changes on a daily basis.)

With DST in effect:
I have the A/C set to come on at 5:30 AM. Dawn is at 7:30 AM. The A/C comes on based on the time the thermostat believes it to be. So at 8:00 AM (the reference time) the A/C is coming on 2.5 hours before reference time.

Without DST in effect:
The A/C is still coming on 2.5 hours ahead of reference time but reference time is now ahead by one hour from actual time. This means that I must change the time the A/C comes on. I must have it come on at 4:30 AM.

Correct?

 

[lxskllr]

I'm not arguing although I am aware that I sometimes come across that way. Keep that in mind.

Let's use an actual time and a reference time. Because the sunrise hasn't changed, the time has. (We're not worried about the tiny amount the sunrise changes on a daily basis.)

With DST in effect:
I have the A/C set to come on at 5:30 AM. Dawn is at 7:30 AM. The A/C comes on based on the time the thermostat believes it to be. So at 8:00 AM (the reference time) the A/C is coming on 2.5 hours before reference time.

Without DST in effect:
The A/C is still coming on 2.5 hours ahead of reference time but reference time is now ahead by one hour from actual time. This means that I must change the time the A/C comes on. I must have it come on at 4:30 AM.

Correct?

I guess it depends on what your app shows you. If your app is working off local time, you'll have to adjust by 1 hour. If it shows you what is set on your thermostat, you don't have to touch it aside from your routine bumps.

 

[Red Squirrel]

I've never heard of having to run A/C to stop mold from growing. It sounds like you have a moisture issue and the A/C is just keeping it at bay by removing the humidity. That must cost a lot to run all the time every day.

But if it's only being run for that then I don't think an hour difference will do much harm. I would personally setup something using raspberry PI or Adruino that you can remote into and have full control, and that also does the DST thing on it's own. Since you're using the A/C for humidity and not cold you could even have it go on based on humidity instead of heat.

But long story short, if you cannot bring the tstat clock back, then just move the whole schedule forward. So if you want it to come on at say, 10am, but the time on the tstat is an hour ahead, you then make it come on at 11am. When it's 11am on the thermostat it will be 10am real time.

 

[Fanatical Meat]

I know my nest & my Parents Honeywell Wi-Fi thermostat adjust to DST time automatically. I imagine all Wi-Fi thermostats' do it.

 

[boomerang]

I guess it depends on what your app shows you. If your app is working off local time, you'll have to adjust by 1 hour. If it shows you what is set on your thermostat, you don't have to touch it aside from your routine bumps.

Both of my residences are in the same time zone. 8 AM here is 8 AM there.

My friend and I are in agreement (at the moment ) that the time the A/C needs to come on must be changed to come on one hour earlier.

My wife has made a compelling argument that nothing needs to be changed. She says that when the thermostat thinks it's 8 AM that it's actually 7 AM but that the A/C is still going to come on 2.5 hours ahead of time regardless.

Now that I've put it in writing, I think she's right. :\

 

[boomerang]

I know my nest & my Parents Honeywell Wi-Fi thermostat adjust to DST time automatically. I imagine all Wi-Fi thermostats' do it.

I have the low end Honeywell. I see nothing in the manual and nothing at their website saying it adjusts automatically. There is nothing in the FAQ at the website about it either. One would think that it would adjust automatically but one would also think they'd make a comment about it.

My recollection is that I had to set the time when I installed it. The instructions tell how to set the time and there are buttons for doing just that.

It's a puzzler.

 

[lxskllr]

Both of my residences are in the same time zone. 8 AM here is 8 AM there.

That's not exactly true. Your thermostat is in a locale that *LOVES* DST, at least until you change it :^D

What matters is the time your thermostat thinks it is, and its relation to sun position.

 

[boomerang]

I've never heard of having to run A/C to stop mold from growing. It sounds like you have a moisture issue and the A/C is just keeping it at bay by removing the humidity. That must cost a lot to run all the time every day.

I knew it was going to come up so I might as well explain the whole thing.

Things are evidently quite different in the tropical climate of southernmost Florida than in the frozen tundra where you live. Ya think? Mold is a huge issue with the high humidity in Florida. The humidity is generally very high in the morning and it drops during the day.

Florida Power & Light suggests to control mold growth in unoccupied residences that the A/C be set to come on 2 hours before sunrise with the temp set at 72F. After a two hour time period, the temp can be bumped up to 88F. During the period of the day with the least sun load and the highest humidity, the A/C will run for a long enough period to very effectively dehumidify the residence. The heat is not a problem, the humidity in conjunction with the heat is.

My electric bills when we're not there run between $20 and $21 per month.

HVAC contractors and FPL used to recommend using humidistats to control the humidity. The A/C would come on when either the humidistat or the thermostat called for it to come on. There are problems associated with relying on those notwithstanding much higher electrical usage which is why FPL is now suggesting the procedure I outlined above. So far, all has been good.

 

[lxskllr]

It's crazy you can't set the time on the thermostat, or that it doesn't take care of time itself. You can control it from the other side of the world, but it doesn't include that basic functionality. That's like a car that does everything, except make left turns. For that, you have to crawl underneath, and move a set pin :^D

 

[Fanatical Meat]

I have the low end Honeywell. I see nothing in the manual and nothing at their website saying it adjusts automatically. There is nothing in the FAQ at the website about it either. One would think that it would adjust automatically but one would also think they'd make a comment about it.

My recollection is that I had to set the time when I installed it. The instructions tell how to set the time and there are buttons for doing just that.

It's a puzzler.

This might simply be a time zone thing. I could easily see entering it once then it automatically updates from there.
I wouldn't be surprised if its the same as my Parents thermostat. My Father never goes high end on something like a thermostat so it must have been pretty cheap for him to get one.

 

[waffleironhead]

Call your neighbor and ask when the system is turning on.

 

[TwiceOver]

This is my first DST with an awesome new WiFi thermostat. Mine changed automatically. Get a different one?

 

[destrekor]

Both of my residences are in the same time zone. 8 AM here is 8 AM there.

My friend and I are in agreement (at the moment ) that the time the A/C needs to come on must be changed to come on one hour earlier.

My wife has made a compelling argument that nothing needs to be changed. She says that when the thermostat thinks it's 8 AM that it's actually 7 AM but that the A/C is still going to come on 2.5 hours ahead of time regardless.

Now that I've put it in writing, I think she's right. :\

Let's do a couple little rough logic statements

if time_at_home = 7am EST
then ac_time_on = 5am EST

if time @ Florida = 8am EDT
then ac_time_on = 6am EDT

if EST = EDT - 1
then 5am EST = 6am EDT

conclusion:
tell you wife she is right as usual, and don't change a thing about your scheduling.

 

[boomerang]

This is my first DST with an awesome new WiFi thermostat. Mine changed automatically. Get a different one?

I have email alerts set up so tomorrow morning I will know what's what. I've got a pretty good handle on how long it will take to get the temperature down to 72 so the time stamp on the email should tell the tale.

Based upon what others are adding to the thread I've got to believe the time is being updated automatically. They just aren't documenting it anywhere.

All that functionality and no means to set the time must mean that the time is being handled through other means. It's two way communication. I don't control the thermostat directly through the app, it goes through their server. They are taking care of the time based on the zip code I entered at their website.

It's like my alarm system here in Michigan. I check a box or two in the configuration at their website and they change the time in my alarm panel when DST comes into play.

I installed the thermostat after DST went into effect last spring so this is the first time I've had this running through my brain. And, I have a huge tendency to overthink things. KISS

 

[boomerang]

tell you wife she is right as usual, and don't change a thing about your scheduling.

I'm changing it back to where it was because she's right.

 

[boomerang]

This might simply be a time zone thing. I could easily see entering it once then it automatically updates from there.
I wouldn't be surprised if its the same as my Parents thermostat. My Father never goes high end on something like a thermostat so it must have been pretty cheap for him to get one.

I like a lot of bells and whistles myself but for whatever reason I went low end on this one. Retail is $119 and Lowe's had it on sale at $99. I barely read the manual initially, just made sure of the wiring and how to get the wireless linked up to the router.

Later, I actually read the manual and found out it pretty much was set up for a heating setup using NG or propane and the place down there has an electric element in the air handler should heat ever actually be required.

There is a hidden menu with a number of settings. I had to change a few. Glad I read the ****ing manual!

 

[Fanatical Meat]

I like a lot of bells and whistles myself but for whatever reason I went low end on this one. Retail is $119 and Lowe's had it on sale at $99. I barely read the manual initially, just made sure of the wiring and how to get the wireless linked up to the router.

Later, I actually read the manual and found out it pretty much was set up for a heating setup using NG or propane and the place down there has an electric element in the air handler should heat ever actually be required.

There is a hidden menu with a number of settings. I had to change a few. Glad I read the ****ing manual!

Being serious I like the look of my nest but my parents Honeywell has a better app and the webpage is set up better than nests. Nest went too apple minimalist.