While we are talking about home heat, Is it better to run your central heater up to the desired temp when you first come

[decocritter]

Which is more efficient, run the heat continuously to desired temp, get the house comfortable (reasoning once you run the heat for a few minutes the ducts are warm and stay warm until house is warm) Thinking the house will slowly lose heat during the night and you will be going to bed anyway, and don't need it so warm.

or Set thermostat lower than Ideal temp and it cycles on and off (ductwork cools in between, so has to warm up each time) but it runs less time and uses less gas.

Am I making any sense?

[Black]

I have mine programmed to kick up an hour or so at wakee-uppee time on weekdays. Every other cycle (4 zones/day) sets it back down to 45.
The rest of the time it's treated as "on demand" and set manually when desired. This year I might raise the minimum during the cold cold snaps (first frozen pipe in 7 years last year) but otherwise this arrangement seems to work great, and coming in from riding a bike in the cold to a 50-something degree house is pretty comfortable.

[Michael]

It sounds like you are wondering about setting back temperatures at night and other times when you aren't home. You can do it by hand, of course, of use a setback thermostat. They save money.

http://www.energystar.gov/index.cfm?c=th...hermostats

[decocritter]

I am wondering about set back, yes.

I have a manual thermostat. I have been cutting it way down when I go to bed and using oil radiator in my master about 14 x 18

But I am also wondering about time lapse of heat loss, as I live in an older uninsulated Plaster wall condo (brick exterior) with lots of window. In other words should I just keep the thermostat low and dress warm. Or heat the place up and hope that it loses heat slowly while I am awake and about.

[Grateful11]

If you have a heat pump the absolute worst thing you can do is jack it way up in the early
morning, the coldest time of the day, it will struggle to build the house back up.

I set mine and pretty much forget it or least I used too. Now my wife has a lot hot flashes and
I usually turn it down by 2 degrees at night and back up in the morning. More than 2 degrees
will bring in the Aux. heat on mine.

[JoeH]

To avoid pipe freezing in northern climes, the minimum recommended setting is usually about 55. As for the rest, whether you do it all at once depends on the type of heat you have. As mentioned, with heat pumps you want gradual raises to the temperature, and there are programmable thermostats that will do that for you. Otherwise, most furnaces and boilers run most efficiently whene the run is longer compared to short on/off cycles.

[decocritter]

No heat pump, just gas furnace.


It is going to get cold here tonight, 39 degrees now and windy.

[Grateful11]

decocritter wrote:
No heat pump, just gas furnace.


It is going to get cold here tonight, 39 degrees now and windy.

You must live near me ;-)

Varying the temp on a gas furnace is not going to have a lot affect on the cost of operation like
a heat pump would. I'm still pretty much a set it and forget it guy, especially in the summer, it's
set on 74 come May or June and stays there until Fall. I used to burn a lot of wood but the
older I get I just can't deal with it. Couldn't cut wood now if I wanted too with my back like it is.
I miss those days of youth.

[davester]

If you have a regular forced air furnace system then setting back the thermostat will make a huge difference in your utility bills. The duct system has an incredibly low thermal mass and thermal inertia so don't worry about warming it up or cooling it down. It is much more important to turn the thermostat down when you don't need the warmth. The cost of running the system is a very simple heat flow equation. If the air in the house is hot relative to the outside then the heat flow to the outside is much more rapid than that of a cooler house and the furnace must work much harder to replace the lost heat. This is why an automatic setback thermostat is a no-brainer and recommended in all energy efficiency studies. The only situation where this is not the case is where you have an unconventional heating system where the system heats the objects in the house rather than the air (some radiant hydronic systems and similar), or is a heat pump system where using setback would result in turning on auxiliary electric heating elements. Even so, some of those systems also benefit from setback strategies. It is unfortunate that some folks subscribe to the old wive's tale that leaving the system turned on all the time will reduce your energy usage. If you don't have one, go buy an automatic setback thermostat. It will pay for itself within a month or two.

[Speedy]

In other words, your forced air heating system will rapidly warm your home when you get up in the morning.

davester wrote:
If you have a regular forced air furnace system then setting back the thermostat will make a huge difference in your utility bills. The duct system has an incredibly low thermal mass and thermal inertia so don't worry about warming it up or cooling it down. It is much more important to turn the thermostat down when you don't need the warmth. The cost of running the system is a very simple heat flow equation. If the air in the house is hot relative to the outside then the heat flow to the outside is much more rapid than that of a cooler house and the furnace must work much harder to replace the lost heat. This is why an automatic setback thermostat is a no-brainer and recommended in all energy efficiency studies. The only situation where this is not the case is where you have an unconventional heating system where the system heats the objects in the house rather than the air (some radiant hydronic systems and similar), or is a heat pump system where using setback would result in turning on auxiliary electric heating elements. Even so, some of those systems also benefit from setback strategies. It is unfortunate that some folks subscribe to the old wive's tale that leaving the system turned on all the time will reduce your energy usage. If you don't have one, go buy an automatic setback thermostat. It will pay for itself within a month or two.