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HI,
I set the thermostat timer for a minimum overnight temperature of 45 degrees, to heat to 70 at 6:30 AM. Effectively, this leaves the furnace turned off overnight. I figure that saves wear on the furnace / fan and saves fuel costs overnight. However, I heard on a radio program that thermostat timers should only have a max differential of about 8 or 10 degrees.
Anybody know what the best settings are?
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use 10 degree setbacks for best efficiency and least problems
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OK, but why? Does 15 or 20 plus degrees of heat differential mean the furnace gets too hot when running to close the gap, or what?
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You wont overheat anything, but there is comfort and air circulation to consider. Yes you will save a bit more but remember you are just heating it back to the temp you need, btus lost btus added. Opinions vary , I set back where it realises a 4 hr drop and for comfort and zone unused areas for less heat. Add insulation for real savings.
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Furnace may not be able to get your heat back up in reasonable time and could lead to frozen pipes in hash weather and a bitchy spouse.

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Frozen pipes??? When you setback the t/stat by 20 degrees??? Not bloody likley when water freezes at 32 degrees F.
Respectfully, Bob
Art wrote:

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Frozen pipes yes Bob , very bloody likely, when it is - 20f we open our cabinets under the sink and some people even leave a drip. At -20f ive seen mains freeze and pipes in enclosed cabinets freeze because of no air circulation. Even at zero f. precautions must be taken. At - 20 he will wake up to a 45 f house if it doesnt have great insulation, and outside walls will be alot colder.
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Ya....OK...It's 50 at the t-stat.
Who says the temp at the pipe in the basement, you know the one that runs right next to that crappy basement window, isn't 25 degrees?
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Haven't been up north much, eh? :-)

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I only turn back about 4-5 degs as it just has to run that much more to catch up and you are not saving anything, I leave the fan on 24-7.
Tom

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Wrong.
Wrong.
Nick
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You are too saving something. The larger the temp difference between inside and outside, the more heat moves. You'd probably save more by turning that fan off when not in use, that could be adding $10 a month to your electric bill.
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The temp stays more constant thru out the house with the fan on 24-7, especially in the winter, its been on for a year. The fan on my furnace is a variable speed so its running at a very low speed when the heat or a/c is not in operation.
Tom
wrote:

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It is still costing you. May not be much, but not much running all the time may still be a lot. Besides the wear and tear on the motor itself, and those aren't cheap.
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Heat is constantly seeking cold to achieve equilibrium. The house is warmer than the outside, so heat is traveling out of the building. You add heat as needed by burning fuel.
Stored heat (sensible heat) is heat that has been absorbed over time. If you allow the air temperature to go too low, the stored heat from the furnishings, fixtures, etc, is also given off. The time to restore it all is making the heater work longer overall than a 10 degree setback.
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That happens whenever the room temp drops. There is no threshold.

Every setback saves money and energy, no matter how small or short, even a 0.1 F 10 minute setback.
Nick
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There have been test showing a diminishing return and a bell on the curve below a certain point. I don't recall where I saw them but you may want to look it up if you doubt it. .
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wrote in message

Your claim..........
Ask you provide the sites then.
We turn the heat pump OFF at 5:00 every day.
It might cycle for a loooong time once its turned back on at 7:am the next morning, but its sole task is to bring heat into the building, and irrevelant is the amount of heat the structure is able to store, or that it loses during the period the heat source is shut off.
--
SVL



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BillC wrote:

If you have a heat pump, 8-10 is likely to produce the best savings in most areas. A larger setback can cause more time in supplemental heat mode where it is less efficient.
For resistance heat, every degree of additional setback will save money, but too much could cause damage to pipes and furniture. With the addition of a grand piano my nightly setback has been reduced.
For gas heat, like I have, you still can have some reduction in efficiency, but for the most part the problem is the secondary effects. I would stick to 15 or less.
--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math
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