THE Thermostat Thread (merged)

Daryl · Intermediate Crude Joined: Oct 10, 2005 Posts: 928

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

purdum · Tar Sands Joined: Feb 15, 2005 Posts: 34 Location: MI, USA

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/progressenergy/setback.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 · Light Sweet Crude Joined: Jun 30, 2004 Posts: 1326

Daryl · Intermediate Crude Joined: Oct 10, 2005 Posts: 928

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 · Intermediate Crude Joined: Feb 03, 2005 Posts: 954

dbarberic · Heavy Crude Joined: Sep 27, 2005 Posts: 240

strider3700

$1200/year? where do you live?
_________________
shame on us, doomed from the start
god have mercy on our dirty little hearts

dbarberic · Heavy Crude Joined: Sep 27, 2005 Posts: 240

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 · Fusion Joined: Apr 25, 2005 Posts: 3448 Location: Maine

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.