Lowering thermostat when leaving - energy efficient?


(Scott Windmiller) #1

I was talking with a friend about lowering the thermostat when leaving and having it return to the regular temperature once you return and when this is efficient and when it is not.
For example: we leave our heat set to 72-73 when we are home and drop it down to 70 when we leave. Some may argue that it may take more energy to return the temp from 70 to 73 then to just let it maintain 73. I would think over a short period that may be the case but over say an 8 hour period, my opinion is, you should save a significant amount.
What are everyone else’s thoughts on this?

Thanks,
Scott


(Beckwith) #2

It saves unless you have a heat pump with secondary electric radiant heat. Even the exception case saves if you have a smart enough system.


(Tim Slagle) #3

Since doing this with SmartThings i have saved on average $15-$25 per month in gas/electric. During really hot months it has saved me $30-$40.

SInce I log all my home data, I have confirmed my HVAC runs (in minutes) about half as much when I do this compared to not doing this.


(Scott Windmiller) #4

That’s what I figured. My wife is home usually during the day but on weekends and at nights I just don’t sea reason to leave it turned up, even if we are only gone for an hour…every little bit helps.

If you don’t mind me asking, what is the difference in degrees you usually have set between being home and away?


(Amauri Viguera) #5

The best thing about this whole “experiment” with ST is that it allows you to gather data to make that sort of conclusion, since everybody’s house is different and everyone’s preference is different.

In my case I have a two zone system, with radiators downstairs and hot water baseboards upstairs. I’ve been logging temperatures for a while and I find that if you go down really low on really cold days, it will take the system a couple of hours to bring the house to a comfortable level. Now depending on prices and your expectations, and your own heating setup, that might be worthwhile, or it might not.

If you know your fuel consumption, oil prices and how long your furnace / AC has to run to keep your house comfortable then you can decide on your own whether it’s efficient to keep it running through the day, to lower it a few degrees or to drop it all the way to the floor.

One of the other advantages of this whole “connected” business is that you can decide on the fly, or even be proactive about it. If you know tomorrow it’s gonna be 5° outside all day, you might decide to run a different schedule that keeps the thermostat at 70° so the house never gets too cold. Or if it’s going to be 45° instead then you can drop it down to 60° while the house is empty and fire everything up a couple of hours before people arrive.


(Scott Windmiller) #6

Good point. How are you guys “logging” the data? I know ST will show you the activity but is there a way to view it better?


(Tim Slagle) #7

(Amauri Viguera) #8

What he said…

I’m personally using thingspeak myself, but I haven’t used xively to say that it’s better or worse. This is the kind of nonsense temperatures we’ve had to deal with here in the NorthEast, so that’s why I’ve become more and more interested in keeping track of how hard my furnace is working…


(Carson Dallum) #9

Here’s a link with a quick overview of why lowering/raising the temp can be beneficial.

http://energy.gov/energysaver/articles/thermostats


(Ron S) #10

Sorry for being a little off topic. You mentioned hot water baseboard upstairs. May I ask which thermostat are you using for that? I am desperately looking to replace a freaking White Rodgers. Picture in this thread:


(Amauri Viguera) #11

Sadly, I don’t think we have the same problems, since the guy I purchased the house from a while back apparently loaded it for bear.

But from the picture it looks like you have a standard low voltage system up there, so even a Nest would work, connected to W1 and RH. At least that’s what I see in their compatibility checker.


(Ron S) #12

Thanks for the info but NEST does require a Common. Right?


(Amauri Viguera) #13

According to them, it doesn’t in 99% of the cases.

They have a compatibility checker on their site… you tell them what wires you have and they tell you if it’s compatible. You can see from the picture I posted that it should work fine with your setup.

Both good news since you get to join in and play, and bad news for your checking account. :smile:


(Ron S) #14

No harm in getting one and giving it a shot… :wink:


(Scott Windmiller) #15

@tslagle13 I just setup GroveStreams…thanks!


#16

I use the CT30 with a Zwave radio module in my zoned hot water baseboard system. These were sold under various different brands and can be had for cheap on ebay (I paid $30 each for 6 of them). For the z-wave version of this you can run on batteries (3 x AA) with no common wire. The draw back is that the batteries only last 3-4 months. I have 6 thermostats, so it becomes quite the chore to keep them all stocked with fresh batteries.


(Ron S) #17

K. Not being handy at all, will have to catch hold of a Hvac guy! The company who had serviced my house has no clue what nest, ecobee or Honeywell wifis are. :frowning: forget about zwave! I am kind of desperate. The freaking thermostat I have is off by 7-8 degrees and cannot be calibrated at all. Being a first time home owner and first year of ownership and with no funds, I am all the more jittery and scared. And the freaking baseboard is making so much bloody noise that missus and I can’t even sleep and that explains my late night and early morning posts. :frowning:

I am so going to open that thing up and at least attempt a ct30 or 100 if that works once I figure out how to turn off the power to it in the breaker box (assuming I used the right term). It’s not even freaking labelled.


#18

You can definitely do this yourself. No circuit breakers required. The wires to the thermostat are 24V AC, and the worst thing that happens if you short them is the boiler fires up.


(Scott Windmiller) #19

I don’t have a common wire and was in the same situation. I bought the CT-101 which can be picked up at a Lowes store. AS far as I know it’s the same as the 2gig ct100 but “works with Iris”. Right now I have it connected without the C wire and it works just fine. I looked thru all the options and I could either 1)just use batteries 2) run a C wire 3) use an AC adapter to work as the C wire.
If it works on batteries then I will just stick with that.
My next option would be the ac adapter. I have an unused outlet behind the thermostat in the kitchen up high…on top of the upper cabinets. My plan was a small hole by the outlet and run the wire down inside the wall pullin it out where the others come out.
Last option would be running the C wire. I’m pretty handy but still may call an HVAC guy, the HVAC cost too much for me to make a stupid mistake.


(Ron S) #20

Ok… Project for this weekend. :frowning: and if there are no posts from me after that… Please post a RIP notification for me. :slight_smile: