Home Thermostats

[JGoodish]

Does anyone have quantified numbers for the savings a setback thermostat can produce in home heating/cooling bills?

I live in PA, which means that temperatures are hot in the summer and cold in the winter. Complicating our potential "savings" from a thermostat is that my wife and I work somewhat opposite hours, so there is usually someone at home most of the time (i.e. the house isn't empty every weekday from 8a-5p, etc.) So, our opportunity for setback savings would be when we are out on the weekends, or overnight when everyone is asleep. Electricity rate is approximately $0.11/kWH and we presently use an average of 837kWH per month for our approximately 2400sqft. home.

Given the fact that the house is usually not unoccupied for long stretches of time, I am skeptical of the savings that I will realize over shorter periods (such as a few hours to a day) several times per month. When we vacation a couple times a year, we do adjust it then, but usually forget when we're out for an afternoon or on a day trip (and would probably still forget even if we could adjust it remotely via an app).

I've considered the Nest or similar products, but neither my wife or I can tolerate a temperature swing of more than about 1 degree (her in the summer, me in the winter), and our thermostat is in the dining room, which gets almost no traffic even when we are home.

Not sure the investment in a "smarter" thermostat would be worth it for us, but maybe I'm missing something.


JKG

 

[N801BH]

Does anyone have quantified numbers for the savings a setback thermostat can produce in home heating/cooling bills?

I live in PA, which means that temperatures are hot in the summer and cold in the winter. Complicating our potential "savings" from a thermostat is that my wife and I work somewhat opposite hours, so there is usually someone at home most of the time (i.e. the house isn't empty every weekday from 8a-5p, etc.) So, our opportunity for setback savings would be when we are out on the weekends, or overnight when everyone is asleep. Electricity rate is approximately $0.11/kWH and we presently use an average of 837kWH per month for our approximately 2400sqft. home.

Given the fact that the house is usually not unoccupied for long stretches of time, I am skeptical of the savings that I will realize over shorter periods (such as a few hours to a day) several times per month. When we vacation a couple times a year, we do adjust it then, but usually forget when we're out for an afternoon or on a day trip (and would probably still forget even if we could adjust it remotely via an app).

I've considered the Nest or similar products, but neither my wife or I can tolerate a temperature swing of more than about 1 degree (her in the summer, me in the winter), and our thermostat is in the dining room, which gets almost no traffic even when we are home.

Not sure the investment in a "smarter" thermostat would be worth it for us, but maybe I'm missing something.


JKG

Your schedule defeats the set back function of the Thermostat...

Not a bad energy use for 2400 Sq Ft...

 

[Matthew]

It's tough to gauge energy savings. If you let the house get warm during the day while you are gone, then cool off just before you get home are you really saving anything over leaving the temp the same all day? I don't know.

What really is nice is in the winter: let it automatically get cooler overnight, then warm up just before the alarm goes off.

 

[Geico266]

Check out the new "smart thermostats". You can control them with your phone.

 

[dans2992]

The nest will detect when you're home or not. I think you can supplement the "occupancy detection" with their smoke alarm, but then you're talking a bigger investment.

Something else to consider is that if your wife likes (or tolerates) a colder/hotter temp, you can change the set point when she is at home vs. you...


Sent from my iPhone using Tapatalk

 

[JGoodish]

Your schedule defeats the set back function of the Thermostat...

Not a bad energy use for 2400 Sq Ft...

Nice to know on the energy use, as I really haven't done a detailed comparison of energy use among similar homes. My electric consumption will go from maybe 400-500kWH in the dead of winter (with gas heat) to 1400-1500kWH in the peak of summer, but the trailing 12 months were right around 10,000kWH total.


JKG

 

[James331]

I've not heard good review of the NEST, check out some review on Home Depot.

If you can't handle a 1 degree swing, you're going to be paying a lot for energy periorid.

 

[denverpilot]

Nothing but the cheapest dumbest setback thermostat will ever pay back itself in savings unless calculated over at least a decade.

Not impressed with Nest. When we put in the new furnace (higher efficiency which saves a lot more over time than the t-stat will) the manufacturer's smart t-stat was a lot smarter than Nest. It'd drive a lot more things if we had them. We haven't done it, but the new t-stat will happily control multi-fuel setups and could ring up the pellet stove if we desired.

Most folks doing multi-fuel say Nest is horrible at that. An afterthought at best.

The manufacturer's t-stat grabs weather from the Internet and can predict after a while how long it needs to call for heat or cooling to meet a setpoint at the exact time it's been requested, can control humidifiers, dehumidifiers, and outside air vents to meet humidity requests while also knowing not to frost windows, manage various air filtration systems and alert when they need service, fully internet connected for remote operation or checking on the temp at the house in bad weather, etc etc etc.

By far the best thing ever for comfort has been the continuously variable blower and being able to leave it on all winter at a low, almost imperceptible, air circulation level now that our basement air returns are somewhat sorted out. No cold or hot spots, air just keeps slowly moving around the house and mixing. We considered zoning the basement vs the upstairs but in the end, it wasn't necessary. The manufacturer's system would gladly do that, too.

 

[wsuffa]

For your schedule, I don't think the setback will make much difference, unless you are both sleeping at the same time.

I have a setback - it came with the furnace - but the higher efficiency furnace and AC saves far more. Well worth the price for the new furnace. Last time I did a furnace change (old house, Ohio) we cut 40% off the bill.

More insulation also helps.

I also put in a wood stove insert - makes all the difference in the winter. Wood only costs me the rental cost of the splitter.

 

[SteveR]

I have had 3 nests in two different houses. It is decent but has some significant flaws. The auto-scheduling feature is overhyped and will only work for someone with a very regular schedule. However the user interface is very good, it is very, very simple to make quick adjustments to the schedule even from my cell phone. Right now we have a 2,300 SF house and our electric bill is running about $110. We have a 2000SF rent house two blocks away with a "dumb" thermostat that the renter leaves on a constant temperature, and their bill is $200 when ours is $110. The two houses are identical in terms o construction type, unit efficiency, insulation, etc., and we both pay about $.10 per kw/hr, and keep the thermostats at the same temp.

About $20 to $30 of the cost difference is due to LED lighting. My house is all LED, theirs is all incandescent which are terribly inefficient but also add a huge amount of heat to the house, meaning the HVAC has to run a little more. About $40 to $50 of the savings is due to setting the thermostat back. Another nice feature is that the nest shows you daily runtime, but only records 10 days of data...a year, or forever, would be more useful. However, between checking usage of the HVAC and power use from data recorded by our smart meter, it is quickly apparent that setting the thermostat back for 8 to 10 hours a day, particularly the hottest part of the day, can easily save 30%. One of the biggest reasons is Newtons law of heating and cooling, which summarized states that the rate of transfer of heat is proportionate to the temperature difference between two objects, which is really very intuitive. I'm a licensed professional engineer and I design mechanical and electrical systems for buildings of all types, including lighting and HVAC systems for small up to large high-rise buildings, so I have a good understanding of how this works. Trust me, every minute you have your thermostat set back saves energy, and the more aggressive you are with it the more you save. Our nest easily saves its own cost every year, but any easily to use programmable thermostat could do the same thing. You could do it manually if you. Are disciplined enough, but most people aren't. And I like to have the ability to turn the AC on when we are an hour away from home after being gone for a while...that way it is comfortable when we get there. Granted, I don't mind the house being a few degrees warm for a while. The occupant sensing feature of the nest is great, and no other smart thermostat has this exact feature. If you just set the thermostat back when you leave you don't need this, but I don't always remember, and my wife doesn't give it any thought.

My complaints about the Nest are:

1. One of them had a bad base that created heat and therefore caused the thermostat to consistently read high by about 5 degrees.

2. Right now my nest has issues with my ATT router, where online access somehow becomes disabled until someone walks in front of the thermostat. That of course makes the mobile app useless. I didn't have this issue with a Cisco router.

3. (From my Amazon review): When installed with a heat pump with auxiliary heat (i.e., electric resistance heating), the Nest runs aux heat far more than needed, wasting a huge amount of energy. Modern heat pumps are more efficient than electric resistance heating (i.e., COP is greater than 1) even when the temperature drops into the 20s. However, the Nest compressor lockout minimum temperature is 35 degrees. I.e., it won't use your heat pump below 35 degrees, even though it is significantly more efficient. So if you paid extra for an efficient heat pump, the Nest negates that efficiency by turning off the heat pump and running electric resistance heating instead. This is absolutely awful for a thermostat that claims to save energy.

The only way I've gotten around this is to set up the strip heat as "emergency heat". Then the Nest won't use it at all unless I manually turn on emergency heat. The problem is that the nest should make this decision on its own...i.e., I want to use the heat pump down to 20 degrees or so, then use aux heat below that temperature where the heat pump won't heat the house or is less efficient. Nest won't do this automatically however. Additionally, once on emergency heat, the software prevents you from using other Nest features, like auto away, it also prevents you from modifying the schedule when in emergency mode. The software forces you to turn off emergency mode, then make your changes, then go back to emergency mode. Nest needs to consult an engineer or two who actually understand operation of basic HVAC systems so that the thermostat will operate properly.

We're building a new house next year and right now I would put two nests in it. Not necessarily because the nest is best, but because it mostly does what I want and I familiar with it. I wish someone would come out with a "smarter" thermostat that would log data infinitely, and fix the heat pump issue.

 

[silver-eagle]

I ran a setback through the winter back 11PM to 4.30 pm just before we all got home. On those days when I worked from home, I just threw on a sweater or an extra shirt. Over night and day was 64 degrees, dinner and evening was 69. My brother used to run his house at 62 all winter. I worked with a woman who did 55 all winter.
Frankly, the best part of a setback is to reset the temp even after someone pushed it up. I cannot say it saved big buxks but even a few a month helps.

 

[asgcpa]

Does anyone have quantified numbers for the savings a setback thermostat can produce in home heating/cooling bills?

I live in PA, which means that temperatures are hot in the summer and cold in the winter. Complicating our potential "savings" from a thermostat is that my wife and I work somewhat opposite hours, so there is usually someone at home most of the time (i.e. the house isn't empty every weekday from 8a-5p, etc.) So, our opportunity for setback savings would be when we are out on the weekends, or overnight when everyone is asleep. Electricity rate is approximately $0.11/kWH and we presently use an average of 837kWH per month for our approximately 2400sqft. home.

Given the fact that the house is usually not unoccupied for long stretches of time, I am skeptical of the savings that I will realize over shorter periods (such as a few hours to a day) several times per month. When we vacation a couple times a year, we do adjust it then, but usually forget when we're out for an afternoon or on a day trip (and would probably still forget even if we could adjust it remotely via an app).

I've considered the Nest or similar products, but neither my wife or I can tolerate a temperature swing of more than about 1 degree (her in the summer, me in the winter), and our thermostat is in the dining room, which gets almost no traffic even when we are home.

Not sure the investment in a "smarter" thermostat would be worth it for us, but maybe I'm missing something.


JKG

We have a 2100 sf home. Three floors. We use the nest. It's ok, just have to monitor the darn thing.

 

[SkyDog58]

Your schedule defeats the set back function of the Thermostat...

Yep. When spouses work different shifts, the utility bills go up a bit.

The thermostat is at a comfort level more hours each day.
The TV is on more.
The lights are on more.
The stove or microwave get used more.
Separate showers....

 

[deonb]

I have a different schedule with myself, nevermind with my wife. My days are anywhere between 20 and 30 hours long - seldom will I have 2x 24 hour days in a row.

So I had to basically disable all of the Nest automatic and even manual timing for it to even remotely work.

So for me the Nest basically provides a 3 degree range and will try and keep the temperature constant within that. However, it's not even good at that. I thought for some reason that the Nest uses a PID-based algorithm to predict temperature direction and compensate for it before it's needed - thereby making it possible to keep the temperature in a narrow range. However, it doesn't do that. It's fairly dumb - it just turns on the heat/cool when the limits are reached.

The 3 degree swing is too high for me - especially since that's at the point of the thermostat. The further away places will swing by about 6 degrees as a result.

I also have the problem with Nest not connecting to my XFinity (Comcast) router sometimes until you go stand in front of it and wave your arms.

If I had to do it over, I'd just put in an Arduino and a thermocouple.

 

[Stewartb]

ADT installed thermostats that allow me to adjust remotely using a phone app. That's the ideal solution for me. I don't need a smart thermostat, but one that can be set/reset while I'm out of the house is helpful.

 

[John221us]

I bought the Honeywell Wifi thermostat, instead of the nest. It has more control and will do a 1 degree range, instead of three. I have been happy with it. I like being able to override the schedule from my phone. I work from home a lot and so does my girlfriend, so the schedule changes all the time. I doubt it will ever pay for itself. I just like the control.

 

[wsuffa]

One other thing to keep in mind: Nest is owned by Google. Any data it can glean fro you - or the thermostat - is fair game for them to collect and mine as they see fit.

Personally, that makes me uncomfortable enough that I won't use one.

 

[SoonerAviator]

We've been using a basic 7-day programmable t-stat for a few years. Has wake/leave/return/sleep settings for each day. Our schedules are fairly consistent, so I'm sure it saves some money, but our HVAC units are fairly old (90's models at best), and the 3K sq ft of poorly insulated home (due to design, not because of cost) is going to be expensive no matter what. I would save a ton by upgrading the equipment over what the t-stat saves.

 

[N801BH]

I bought the Honeywell Wifi thermostat, instead of the nest. It has more control and will do a 1 degree range, instead of three. I have been happy with it. I like being able to override the schedule from my phone. I work from home a lot and so does my girlfriend, so the schedule changes all the time. I doubt it will ever pay for itself. I just like the control.

Most, if not all human,s cannot detect a 1 degree difference... I know it is good to be able to control it that tight but the unintended fallout will cause more damage then added comfort....

Nothing kills AC compressors faster then " quick cycling" and a 1 degree delta will do that.. The smarter T stats have a delay ( usually 5 minutes) function to prevent quick cycling... So during a hot summer day you will get a 30 minute or so on and 5 minute off sequence.. If it is real hot outside you will most probably exceed the 1 degree split..

Also with high eff equipment like ground source heat pumps, reverse cycle units and on the heating side they have heat strips ( emergency heating event)... Constant on and off cycles will degrade the life of those components.. IMHO...YMMV.

 

[JGoodish]

Most, if not all human,s cannot detect a 1 degree difference... I know it is good to be able to control it that tight but the unintended fallout will cause more damage then added comfort....

Nothing kills AC compressors faster then " quick cycling" and a 1 degree delta will do that.. The smarter T stats have a delay ( usually 5 minutes) function to prevent quick cycling... So during a hot summer day you will get a 30 minute or so on and 5 minute off sequence.. If it is real hot outside you will most probably exceed the 1 degree split..

Also with high eff equipment like ground source heat pumps, reverse cycle units and on the heating side they have heat strips ( emergency heating event)... Constant on and off cycles will degrade the life of those components.. IMHO...YMMV.

Well, I don't know, both my wife and I can easily detect a 1 degree difference without looking. Repeatedly and reliably.

Unless the building is made of swiss cheese or there is a problem in the HVAC system, most standard AC compressors shouldn't be short cycling to maintain a constant indoor air temperature.


JKG

 

[N801BH]

Well, I don't know, both my wife and I can easily detect a 1 degree difference without looking. Repeatedly and reliably.

Unless the building is made of swiss cheese or there is a problem in the HVAC system, most standard AC compressors shouldn't be short cycling to maintain a constant indoor air temperature.


JKG

Congrats....

ps.. Is your last name Honeywell.........

 

[JGoodish]

Congrats....

ps.. Is your last name Honeywell.........

No, and as you might expect, my wife is the problem. If she would just leave the thermostat where I set it, things would be far less complicated.

Understand that I'm talking about a one degree difference in the SETTING, but presumably the fluctuation in ambient temperature would be fairly constant for adjacent thermostat settings.


JKG

 

[SCCutler]

I have the Honeywell remote at my log shack, works great and I can set back the temp about 2 hours before arriving.

 

[TazzyTazzy]

I'll give my vote for the Nest. Sometimes the in-laws stay at our house when we are away and just can't seem to figure out any thermostat. This weekend, we flew down to Oceano (L52) and they took over our house. We get a call saying "I think the thermostat is going crazy, the heater is on!". Opened up my phone, and sure enough, someone set it to 85 degrees. A few taps later, and everything was reset without having to explain anything to them.

Unsure how you can mis-read the nest. Turn counter-clockwise for colder, turn clockwise for hotter. Big numbers show the setting you want. On top of that, it _WAS_ set to Cool (not Cool + Heat). So, they were playing with it for some reason.

Also, if we have been gone for a few days, we'll tell the Nest we are no longer "away" on our drive home from the airport or whatever camping trip we are returning from. The house will be nice and cool for us when we get home.

 

[John221us]

Most, if not all human,s cannot detect a 1 degree difference... I know it is good to be able to control it that tight but the unintended fallout will cause more damage then added comfort....

Nothing kills AC compressors faster then " quick cycling" and a 1 degree delta will do that.. The smarter T stats have a delay ( usually 5 minutes) function to prevent quick cycling... So during a hot summer day you will get a 30 minute or so on and 5 minute off sequence.. If it is real hot outside you will most probably exceed the 1 degree split..

Also with high eff equipment like ground source heat pumps, reverse cycle units and on the heating side they have heat strips ( emergency heating event)... Constant on and off cycles will degrade the life of those components.. IMHO...YMMV.

Lots of things last longer if you don't use them as much. It is an adjustable setting on the Honeywell and not on the Nest. I don't like a three degree flux in temperature and I do notice the difference. This thermostat does have the delay (it should be pretty smart for $200).

 

[denverpilot]

Seeing the stories about the Nest in this thread really solidified my liking of the manufacturer's smart stat as our choice when we replaced the furnace.

Seems to be WAY smarter than the Nest and the multi-fuel story above was hilarious. This one was designed by HVAC engineers and in the hidden settings menu (my installer lets me play and showed me which things NOT to change) cycle times, lockout periods, humidity lockouts, etc etc etc ... All in there.

Even settings for various mandatory efficiency ratings that some States require for the variable fan vs amount of heating/cooling, and all the fancy "remote cycling" stuff that some utilities give discounts for.

Really didn't make the wrong decision going with the Bryant made smart stat over the Nest, it appears.

If you find yourself at a time to upgrade the furnace, make sure it has a manufacturer's smart stat if you like such gadgets. This thing rocks.