Turn thermostat down or leave steady?

[Stormin Mormon]

Next week, I'll ask how to hang the roll of toilet paper. Or how to change a light bulb.

[Stormin Mormon]

Well, sad to hear that you live in an over regulated part of the world.

[Stormin Mormon]

I've had those kind of days. I call em "double ended" days.

[Stormin Mormon]

I've met enough people who think slamming the thermostat makes it heat faster. Dunno. They must learn from driving a car where tromping the gas pedal throws it into four barrel?

[Jules]

I think with most electric stoves the temperature of the heating element is directly proportional to the dial setting (regardless of whether the stove's altering the resistance of the system or cycling power on and off like a furnace) - there's not necessarily any feedback from the heating element to the controller via a thermostat.

So for a stove, yes giving it full power until it boils and then turning it down to maintain boiling *is* quicker than just boiling it at the lower setting (unless you're using coated pans, because you'll kill the non-stick coating by giving them full power :-)

Now, a thermostat-controlled system is a different matter...

1) Is the heating device capable of variable heat according to demand? Most aren't - but I'm sure there are some furnaces out there (for example) that can switch in extra burners and produce a hotter output if the difference between current temperature and 'desired temperature' (as set by the 'stat) is great - in those cases turning the stat up to 11 might actually make a difference :-) 2) The dynamics of the system if there's just one 'stat (and the system design's poor) might be tricky - the area with the 'stat in might reach desired temperature before the rest of the building feels warm, so turning the thermostat way up could result in a situation where the rooms that the people are actually in feel warmer sooner than they would if the thermostat were just set to desired temp (and the room with the stat in will end up feeling too hot until the temperature of the whole building evens out)

In other words, it's not quite clear-cut I think...

cheers

Jules

[Kurt Ullman]

I think it just an extension of the well known fact that if you press the button repeatedly the elevator will arrive faster.

[Frank]

I usually think, forced hot air. Boiler, I don't know but imagine water in tank would keep fairly hot if not circulated. Thermodynamically, turning temperature down saves energy.

[Stormin Mormon]

You are so, so right. Thanks for a smile.

[Stormin Mormon]

Oh, I dunno. The carbon that made natural gas came out of the environment. Some time back, but even so.

If you raise the carbon dioxide, the plants thrive, and the system balances itself down again. The planet is self adjusting.

[TimR]

On Oct 30, 8:24=A0am, Jules . Anything with a lot of inertia, like slab heat, is best left alone

Does that necessarily follow? Anything with a lot of inertia will cool off much more slowly too. So you don't have nearly as far to recover when you raise the temp again.

Maybe that part of the question should be rephrased as a time constant.

Drop the temperature by 10 degrees. There will be a transient period while the temperature is falling. Then there will be a steady state period while the lower temperature is maintained. And another transient period while the upper temperature is reestablished.

Clearly energy use is lower during the first transient period, as in zero.

Clearly energy use is lower during the steady state period due to the lower temperature setting.

Not so clearly energy use is higher during the second transient period, your heat will not cycle until the new steady state is reached.

If lower steady state is never reached because the setback is for too short a time, then it seems logical that energy use during transient periods would average to 50% duty cycle. But this isn't necessarily true, because the time periods may not be equal. Loss of heat to the environment is not at the same rate as gain of heat from the furnace.

[Tony Hwang]

No, It is not regulation. Collective logical common sense.

[Eric]

I think those are the same people who think that by creeping forward at a red light, they can intimidate it into changing to green faster.

Eric Law

[Eric]

Known, thanks to comedian Rich Hall, as "elacceleration". ;^)

Eric Law

[RickH]

If left alone the boiler kicks on maybe once every 4-6 hours for only a short 5-10 minute period (maybe 4 or 5 recyclings of the entire water load).

If you let the house cool for 10 hours while at work, the boiler will have to run several hours to get all the floors (and house contents) heated again. This run is more than the sum amount of time the boiler would have been fired if you had just left it alone. You've never lived with a boiler have you? Air is low mass, it heats up very quickly, radiant heating of the building mass itself takes longer from the same starting temp as the air entering a forced-air system.

Yes, the "rules" are different for forced-air vs under-floor radiant heat, in practice, but not the laws of thermodynamics are not.

[RickH]

TP must unroll from the topside of the roll (so loose end hangs away from the wall). This way pulling the paper up lessens the friction imposed between the roll core and the dispenser hub allowing less- restrictive unrolling. Additionally having the paper hang away from wall, lessens the occurence of fingerprints (and finger nail scratches) on the wall itself caused by people scratching against said wall to find the roll end. Additionally there is better visibility of the roll top as opposed to the roll bottom in finding the paper end in a visual manner (as opposed to a "by feel" manner).

This is a well-known fact, TP must unroll from the top of the roll, not the underside.

[hrhofmann]

Let's drop this and start a new topic if TP is your prime worrry!

[DD_BobK]

Try telling them that the thermostat is just a switch (on-off) not a "gas pedal" like in their car.

cheers Bob

[DD_BobK]

Sorry Rick, you're mistaken...setback always saves energy, you're confusing recovery time, inconvenience & comfort with energy use.

Run the numbers, I'll give you a starting point.

Are we talking CI radiators, baseboard units or in floor radiant heat? Tube material? Estimate or determine the total amount the water in the system. Estimate the weight of the radiators & delivery system. Calc the thermal capacity of the water & the delivery system. Hint: The specific heat of water is 1 btu/lbm degF .... it is left as an exercise for the reader to determine Cp of the other materials in the system.

I think you'll be surprised how little heat is "contained" in the system.

So by your logic I should leave my mountain home heater thermostat set at 68F ALL the time? Day, night and when unoccupied because re- heating all the insulated mass of the house; drywall, flooring, floor framing and furnishings would take a "bunch of energy" ?

I don't think so...my fuel bill is high enough with the set back technique is play.

btw I have lived with boiler / steam heat :)

cheers Bob

[Jules]

I got into the habit of taking the stairs. Often it's quicker, and it's good exercise. Bonus points for being spotted by the same person at either end and claiming you have teleportation powers :-)

[Red Green]

"Stormin Mormon" wrote in news:hcem10 $ikp$ [e-mail]:

BTW, which way does the ground go on a duplex outlet, up or down?

:-)