Should I turn the heat off when I am away from the house?

Question

I have three heat/AC zones in my house. One for downstairs and two for upstairs (one in the master bedroom and the other for the rest). When I leave the house in the morning I turned off all three zones. When I am upstairs I turned off the downstairs heat. Am I saving money or wasting money?

Answer 1

Here is the swing, Yes and No and it depends on the weather that day. One day you’ll save and the next will bite you eating up your savings. Your home in constructed with an insulation barrier which is there to prevent heat transfer. We don't want to let the heat out in the winter or let it in the summer. That barrier has a point or area of equilibrium that shifts with the ambient temperature outside. What you are doing is causing you systems to work harder than they need to. Programmable thermostats can help you operate the systems on your home much more efficiently than you would expect. Remember heat rises and your home thermal equilibrium. Set the downstairs to a cooler temperature during the night (near bed time) that is reasonable (4-5 degrees) cooler than the upstairs. This will maintain the thermal barrier in your home without having the temperature drop to an unreasonable level. Set the time/temperature downstairs timer to begin to cycle 1.5 hours before you wake. This will preheat your home before you slide out of bed. Set the temperature downstairs to 3 degrees below your comfort level for while you’re away. Do the same for the upstairs and remember the heat will rise and the upstairs units most likely will not cycle while you are away. If your systems are newer and have the variable speed indoor section make sure you set the upstairs fan on "circulation" mode. This mode operates the fan speed at 25% of the air velocity, keeps the temperatures even in the home, and consumes about the same as a 100w light bulb. IF you are using the old Honeywell round or any kind of bi-metal mercury switch thermostat get rid of it!!! Those old controls being changed out alone pay for the new thermostats. You can take off 240 hours of system operation per year just by upgrading the thermostats. Keeping those old thermostats is like turning on the system and having it run for ten days straight. Nobody would ever just want to do that.

Answer 2

You are definitely saving money.

Some of the folks pointed out some important things to consider: you don't want your pipes to freeze and wild temperature swings are not good for your house -- so you should use a programmable thermostat to keep the house from getting too cold. You should probably set the thermostat to be at 55-58 when you are away. Of course, if you live in a climate where the outside temperature never drops below freezing and your house is reasonably well insulated then it will probably never drop much below that point anyway.

However, I completely disagree with those who say that you will use more energy when you heat the house back up than you would by keeping it warm all the time. Not only do all (qualified) energy conservation experts agree with this, but it can be explained in terms of very basic high-school level physics:

The best way to think about this is is not in terms of how much energy goes into heating your house, but instead in terms of how much heat you loose. If your house were able to retain 100% of the heat put in, you would never run your furnace at all. But of course, you do loose heat; the work that your furnace then has to do is to make up for the lost heat. Now then, the important thing to remember from physics class is that energy (heat) always wants to move from areas of high energy (the warm inside of your house) to areas of low energy (the cold outdoors). Moreover, the greater the difference in temperature (between the indoors and the outdoors) the faster the heat will move. Therefore, if the inside of your house is 70 degrees it will lose heat at a significantly faster rate than if your house is at 55 degrees. The faster the rate of heat loss, the more total heat loss over the course of the day. The more heat loss, the more the more fuel you need to feed into your furnace to make up for it and the more dollars leave your pocket.

There is another problem with the argument of those who complain that the furnace would have to work too hard to heat back up once you get home. Most furnaces have only two settings: off and on. When your thermostat sends the command, the furnace kicks in full blast until the thermostat tells it to stop. Therefore, the furnace will have to run longer when you get home, but not any harder. The extra time that it has to run in the evening is going to be less than the total time it would have spent on over the course of the day had you left the heat on.

Answer 3

You should never turn the heat off in the winter. There are several reasons why. 1) The temperatures may drop below freezing in your house and pipes may freeze - and other things that you may not realize (i.e. food, electronic devices) that could be damaged by freezing temperatures or condensation. 2) It takes a lot of energy to reheat your house after it has cooled down. You are probably not saving any energy by turning the heat off. 3) As mentioned before, condensation will build up from temperature changes and could cause rust, mold or shorting of electronic equipment or worse (pianos or other musical instruments could be destroyed).

You could lower your temperature to about 55-60 degrees. Sometimes when you heat your home with zones, completely turning off your heat could wreak havoc with your heating system and it takes a long time to get back to normal. It may be different for homes, but I know some of the commercial buildings I've worked with had this problem.

Answer 4

Depending on where you live in the country, you should keep your thermostat(s) at 60 deg. at the very coldest. Reason is that any colder and you could risk getting mold and mildew within the walls or in the attic. Also you are best off to vary the temp. inside the house only by 10 deg max. Get a programmable thermostat if you don't have one and set it to 60 deg while no one is home or in the particular zone, and then at what your comfort level is when you are home or in the particular zone. You will save money in the long run using this method. Also I would discourage running the fan 24 hours a day.

Answer 5

this is an age old debate, but in my opinion, it does not make any sense to keep raising and lowering the temperature in your house. i have seen claims that you can save 10% or so by doing this but hear me out. when you turn off the heat in your house, and come home to a cold one, it takes your heating system a lot longer to bring it up to the temp you want because not only does it have to heat the air, but also the furniture, the florring and everything else in your house, until the temperature stabilizes. i have always told my customers to just set it and forget it. i have never seen a study that says otherwise and actually backs it up with real heating or cooling bills for proof. why don't you be the first to complete one. turn it off and on for one month, then leave it at a nice comfortable 70 degrees for another and compare the bills.

Answer 6

You are probably saving some money. If you don't mind constantly turning on and off the heat in different zones, it can reduce your utility bill. But if you are away from the house for a longer period of time, I would set your thermostat to keep it heated to above freezing to avoid your pipes bursting (an expensive situation to fix).

Answer 7

You're better off to set the thermostat low on all zones and leave them alone. The extra work done by the system to bring the heat back up, after being turned off, kills all the apparent "savings" while off.

Answer 8

where do you live? up north just turn the heat down to 65 during the day, this way when you come home the furnace doesn't work as hard to bring you home to a comfortable zone. one thing you and everybody should do is to have the furnace fan on 24 hrs a day. it was built to do this, it called air replacement.

middle of the country, depends on the temp for that day.

south, would you mind if i came to visit for about three months

Answer 9

my heat is free include rent!!! i keep it at 78 ohh hell yah i stay warm and some times with windows open alittle for fresh air!!! ohh hell yah the best part rent is only 620 better then paying 200-400 a month on gas at my last house i had

Answer 10

you are taking a chance of freezing your pipe better to keep at 55 then to turn off could cost you a lot in repairs