[Daryl]

I have a gas fired furnace. Thre service guy was here the other day and said I should not turn off the heat when I am at work. He said I should also never vary the thermostat by more than two degrees. This is based on the idea that I will use more gas to displace the cold air than to maintain a constant tempatrure.

Anyone agree or disagree with this? Thanks.

[Byron100]

I have a gas fired furnace. Thre service guy was here the other day and said I should not turn off the heat when I am at work. He said I should also never vary the thermostat by more than two degrees. This is based on the idea that I will use more gas to displace the cold air than to maintain a constant tempatrure.

Anyone agree or disagree with this? Thanks.

While it's not a good idea to turn it off except on the milder days, it's usually beneficial to turn it down a few degrees if you're going to be gone for more than a few hours in the day...what I do is to crank it down at night, bump it up to 65 or so in the morning to take the chill out, turn it back down to 60 during the day and back up to 63 when I get home, using a space heater in the room I'm in for extra heat. The lowest you should turn it down to is around 50 or 55 degrees F, however, to keep the pipes from getting too close to freezing...but in a mild climate like Atlanta, that's not likely to be a problem except for the coldest of days.

[purdum]

The service guy may be correct if the setback is for short periods of time. But if you can keep the setback for more than about 6 hours, you will save energy. Most furnaces cycle between fully on or fully off. So, for example, if you set the thermostat back overnight, then during morning warm-up the system simply cycles on for a longer period of time. When setback periods last more than six hours, the longer warm-up cycle requires less energy than would be consumed by the system cycling to maintain temperature during unoccupied times. Here's one link with more details: http://www.advancedenergy.org/progresse ... tback.html

[Guest]

I manage 4 apartments. I keep track of oil usage for each unit. I know my tenants thermostat settings. From my experience, your service guy is wrong. My buildings are 1860 homes with attic insulation and double hung windows. They are not the most energy effecient buildings. I am in the Boston area so we have very cold winters.

My thermostat is set for 40 degrees when I am not home and or asleep. It is set at 55 for for about 15 to 20 minutes before I need heat. If its not enough I just turn it up a bit. My tenants who all have dogs subscribe to the "wont it use more energy to heat it back up" theory. I used 300 gallons of oil last year and my tenants used 550, 700, and 800 gallons. Each unit has its differences so it is not a very well controlled experiment. However, they have more similarities than differences.

While the other posters speak from some higher faith I speak from direct experience. You will save a lot of money if you turn the thermostat down as low as possible without your pipes freezing when you dont need it.

Having more heat in your house increases the temperature difference. The greater the difference the faster you loose heat. Whoever thinks keeping the heat on is a good idea is just wrong. Why schools dont teach thermodynamics in first grade is beyond me.

[WisJim]

I work in a large educational facility with dozens of buildings. We have spent many tens of thousands of dollars putting in night-set back thermostats in most of the buildings over the years to save energy, and the energy savings is carefully documented. Your service person doesn't know what he is talking about, unless you have is a very odd situation.

[Frank]

I agree with the above posters - I installed programmable t-stats a couple of years ago and saved a bunch of money, probably 15-20%.

[PhilBiker]

I have a gas fired furnace. Thre service guy was here the other day and said I should not turn off the heat when I am at work. He said I should also never vary the thermostat by more than two degrees. This is based on the idea that I will use more gas to displace the cold air than to maintain a constant tempatrure.

Anyone agree or disagree with this? Thanks.

The guy's full of shit. Google it.

[Daryl]

Thanks for all your advice. What about airconditioning? On really hot summer days if I leave the AC off all day, it becomes so hot inside the house that my central AC is unable to cool the house down. My genius service guy said that the systems aren't designed to handle temperatures about 90 degress and that I should leave the AC on all day too. ????

I also have an attic fan i.e. cut into the upstairs ceiling, sits on floor of attic pulling air from house up into attic. Any ideas on how to use this in conjunction with AC? Thanks.

[WisJim]

Run the whole-house attic fan in the evening/night when it is cooler and dryer outside than inside, then use the AC when needed when you are home during the day.

Remember that shade trees can make a big difference in the heat gain during a sunny day, by shading the house. Also, light colored shingles make a difference in keeping a house cool. I had read somewhere of a study that showed how much energy could be saved if all homes with dark shingles had light colored shingles instead. Makes a difference in cold climates too, as light shingles keep the snow from melting off the roof as quickly, and a layer of snow helps insulate the roof too.

[aahala]

Thanks for all your advice. What about airconditioning? On really hot summer days if I leave the AC off all day, it becomes so hot inside the house that my central AC is unable to cool the house down. My genius service guy said that the systems aren't designed to handle temperatures about 90 degress and that I should leave the AC on all day too. ????

Can't comment on what your system can handle.

In general, to minimize your own costs, don't heat or air condition
at all if you're not at home. Get a programmable thermastat if you want
the home comfortable at the moment of arrival.

AC is different from heat as to the grid however. If everybody allowed
their homes to warm up all during the day while at work, then had their
AC to work full time to cool down over a short time period, the peak
demand could greatly increase overall costs and perhaps rise above the
level that could be produced, leading to a black out of electricity.

[dbarberic]

Thanks for all your advice. What about airconditioning? On really hot summer days if I leave the AC off all day, it becomes so hot inside the house that my central AC is unable to cool the house down. My genius service guy said that the systems aren't designed to handle temperatures about 90 degress and that I should leave the AC on all day too.

All the writings that I have seen on this topic have mentioned an eight degree difference between high and low settings as key. More than eight degrees requires to much energy to make up the difference and cuts into your savings. Less than eight degrees and your not saving as much as you can.

The other rule of thumb that I have come accross many times is not to set back the thermostat unless the set down period is roughly eight hours or more.

For heat, I keep at 68 when home and 60 when away or sleeping. This got my heating costs down to about $1,200 a year with a 2,300 sq ft house, natural gas, at $8.72 mcf. I'd make it colder, but there are some days that my hands go numb while at the keyboard of my computer in my home office and my wife would kill me.

I applied the same rule for my AC. I keep at 80 when not home and 72 when home or sleeping (I like it cold when I sleep).

[strider3700]

$1200/year? where do you live?

[dbarberic]

$1200/year? where do you live?

Northern Ohio.

[Frank]

Re heat loads, supposedly if you attach foil-backed bubble pack (or just aluminum foil I would suspect) to the underside of rafters i.e. inside the attic, quite a bit of the radiant heat load is eliminated. Not sure if this works as one would think the roof would diminish reflective radiant energy, but it's probably worth researching.

[Revi]

I wonder if our silver painted roof reflects heat in the summer as well as allows snow to slide off. You've seen our house, Frank. Almost every house in my part of Maine has a metal roof, painted with silver paint. It gets warm around here, and I just thought that these shiny roofs may have a function in both summer and winter.

[BabyPeanut]

This is based on the idea that I will use more gas to displace the cold air than to maintain a constant temperature.

Nope. Air moves through your house regardless of whether the furnace is running or not. In fact more air probably moves through your house when the furance is going since the hot air is rising pulling in cold air as it moves out of the house.

Questions About Home Sealing (link)
What is a home envelope?
The exterior of your home is also called the "envelope" or shell. (See the orange line showing the envelope in the diagram at left.) The insulation, outer walls, ceiling, doors, windows, and floors all work together to control airflow in and out of the structure, repel moisture, and prevent heat from being lost or gained inside your home. A high-performance envelope helps maintain a consistent temperature even under extremely hot or cold conditions. The goal of Home Sealing is to improve the home envelope to make homes more comfortable and energy efficient.

What is air sealing and why is it important?
Air sealing is simply closing holes, cracks, and gaps where air can pass into or out of your home. On hot and cold days, you pay money to run an air conditioner or a furnace to maintain your home at a comfortable temperature. A house that leaks air costs more to heat or cool because your system must work longer to "condition" the air. In addition, if you happen to sit next to one of those leaks, you are uncomfortable because the room feels hotter or colder. Sealing those air leaks will help you maintain your home at a comfortable temperature all year long and help lower energy bills.

The biggest holes are most often found in the attic and the basement. Caulk, spray foam, and weather stripping are the most common materials used for air sealing.

[url=http://www.energystar.gov/ia/home_improvement/images/house-leaks-with-text-780.jpg]
(click to enlarge)[/url]

More at web site (link)

[Guest]

Revi,

I think that metal roofs not only last longer, but perform the functions you point out quite well (especially allowing snow to slide off). I need to re-shingle next year and am considering metal although my better-half isn't sure that she'll like the pitter-patter. (We have a saltbox with large roof area over the bedrooms.)

[Frank]

Hmmm, that was me. Not sure why I keep getting logged out, but I do.

[Tanada]

Revi,

I think that metal roofs not only last longer, but perform the functions you point out quite well (especially allowing snow to slide off). I need to re-shingle next year and am considering metal although my better-half isn't sure that she'll like the pitter-patter. (We have a saltbox with large roof area over the bedrooms.)

Thats easy to fix by isolating the attic sound from the rest of the house with a little soud insulation, though it might take more effort.

[strider3700]

metal roofing is pretty expensive compaired to asphalt shingles. I just picked up everything to do my shop, 624 sqft of panels and the ridge and foam and screws... came to just under $800 cdn. shingles would be about half of that I think.

of course in my rainy always shaded back yard the moss destroys asphalt in about 5 years but the metal is always just a visit with the hose away from like new.

I'll tell you what the noise is like next week. I expect it to be loud until the insulation goes in.