Programmable Thermostats

[HowardRoark]

Do one of you smart people know if there is an optimal amount to let your heat go down during the day if it will be going back up later in the day? It would seem that there must be a point on the curve where it is more inefficient if it goes too low.

[MJZiggy]

I think it depends on all sorts of interesting things like what temperature you want the room to be when you get home. I let mine drop to 64 in the winter and then incrementally increase it so that it's 70 when I get back. Most people I know in Wisconsin would never dream of keeping it as warm as 70 in the winter (that's what you have a sweater for, dear). In other words, I think the smart people will need another number to the the math comparison between the BTUs to maintain a certain temperature and those required to increase it.

[red]

try putting on some headphones

problem solved

[hoosier]

I would think it depends what kind of heating system you have.

[Patler]

For the most in energy savings (in the winter), you want your set back temp to be such that your furnace does not run at all while you are gone, but starts in time to get your house to an acceptable temp when your return. In that way you are replacing only the minimum BTUs necessary for your comfort. Whether this is practical and will actually work for you or not may depend on how "smart" your heating system is, or how tolerant you are, because the practicality of it isn't always acceptable to everyone. A few of the issues that arise are:

- Obviously, if your house losses heat quickly and it is extremely cold out side, you wouldn't want your house to get so cold as to freeze drains, etc. This shouldn't be an issue unless you have a situation like I did when I was first married, with a house on Lake Superior that had no insulation in the walls or attic. Our shower drain always froze!

- It may take a long time for your heating system to get back up to temp. Most have duty cycle limitations. After running at max ouput for a given time, they will cycle off for a while even if the set temperature has not been reached. On a very cold day it will take your system a lot longer to recover than on a less cold day, even if both are starting from the same temperature, because of the continuing heat loss during recovery. The smartest of smart heating systems take this into consideration, factor in the outside temperature, and adjust the "start" time so that the desired temp is achieved at the prescribed time. If you have a basic set back thermostat, and you program for it to began recovery at the same time each day, it might be acceptable on a warm day, but feel cold on a cold day because it has not yet recovered. Conversely, if you set it so it recovers in time on the coldest days, it may recover far in advance of your return on a warm day, and waste fuel.

- Objects and surfaces cool, and may take a long time to warm back up even after the air has achieved temp. Some people object to their furniture, walls and other "things" feeling cold when they get home. A higher set back temp maintains "things" at higher temperatures.

- Humidity can be an issue, especially if you have a very tight house and/or you use a humidifier so that you have high trapped humidity in the house. If you then let your house temperature drop a lot, the relative humidity can get quite high. This might cause condensation issues on windows, etc.

Best procedure, start somewhere, and if everything is fine when you get home, set it back another degree. Keep doing that until you don't like the results. If you have just a simple thermostat that uses the same times and temps each of the setback days, try being more aggressive in your setback temp in the spring and fall, less so in the dead of winter because of recovery time.

[MJZiggy]

Sounds complicated. I just moved someplace warmer so I don't have to worry about it as much.

[Patler]

Sounds complicated. I just moved someplace warmer so I don't have to worry about it as much.

Hey, I thought my conclusion was pretty simple!
Just start somewhere and keep setting it back more and more until you find your tolerance point!

Now, lets talk about saving on that AC bill.........

[Guiness]

Roark, it doesn't get inefficient as the temperature goes lower, it actually gets more efficient. Heat loss will decrease as temperature inside your house approaches the temperature outside.

Patler's got it right in the first paragraph. You want to prevent your furnace from turning on during the day. The trick is to find the time to have the furnace turn back on so that the house reaches an acceptable temp when you get back.

The other factors Patler mentioned need to be considered, and I'll add that the type of plants you have in the house do as well. If you've got some tropicals, you don't want the temperature dipping much below 12-15C.

I'll also bring up curtains - if your windows aren't great, thermal backed curtains make a big difference.

And yes, AC is a totally different matter, mostly due to the amount of work central AC does removing the humidity from the house. It's better to 'set it and leave it.'

[SkinBasket]

I installed one in my parents house. Biggest mistake ever. My mom treats technology like a retard, just pushing buttons on things she doesn't understand to make a point - that she doesn't understand, and refuses to understand them. So every time I visit, I'm forced to reprogram the thing, explain how it works, explain how to adjust he temperature manually, and then get to hear, "Well, why don't we just put the old one back on?"

I usually keep the temp at 64-68 during the day, and hit spikes of 70 at 4am when my wife gets up and at 5p when she gets home so she doesn't complain.

[MJZiggy]

Hey, I thought my conclusion was pretty simple!
Just start somewhere and keep setting it back more and more until you find your tolerance point!

Now, lets talk about saving on that AC bill.........

Where I live we have lots of trees. I only run AC a couple days a year...

[mraynrand]

I have only two settings on my thermostat: Hot and Smokin'!

[Upnorth]

We have a century home with radiant heat. We just leave the temp constant all the time as if you let the temp come down, then the radiant takes awhie to catch up and then it shoots right by and gets way to hot.
The home we own is twice the size of our last house but with radiant heat it cost half as much to heat. That and when you come in from -40 there is no better feeling than sitting on a radiator full of hot water.

[mraynrand]

We have a century home with radiant heat. We just leave the temp constant all the time as if you let the temp come down, then the radiant takes awhie to catch up and then it shoots right by and gets way to hot.
The home we own is twice the size of our last house but with radiant heat it cost half as much to heat. That and when you come in from -40 there is no better feeling than sitting on a radiator full of hot water.

There's a regulator you can get that prevents this overheating. It's a bit pricey, but well worth it. We let the place go down to 60 during the day and overnight. Takes an hour, hour 1/2 to heat back up, but we have a lot of rooms with high ceilings so more volume - and it's a 1923 house..... Any lower than 60 and it takes too long to heat.

[GrnBay007]

My thermostat is really easy to operate. Be the first one up in the morning to give the house a burst of heat so I'm able to get my teens out of bed!! Once we are ready to go the temp goes way down till about 7pm.

[woodbuck27]

I think it depends on all sorts of interesting things like what temperature you want the room to be when you get home. I let mine drop to 64 in the winter and then incrementally increase it so that it's 70 when I get back. Most people I know in Wisconsin would never dream of keeping it as warm as 70 in the winter (that's what you have a sweater for, dear). In other words, I think the smart people will need another number to the the math comparison between the BTUs to maintain a certain temperature and those required to increase it.

WOW! Alot goin' on in that response.