Buzzing breaker--source of high electric bill?

[CNYCacher]

Absolutely. And if you set back and lose a bunch of heat to the outside you must replace it BTU for BTU in order to re-achieve 70*. You're thinking because you've reduced delta T between inside and outside you will slow down the transfer, that is true

Yes, that is what I am thinking.  Glad you agree as well.

but the resulting slow down in transfer to the outside will truly be miniscule

Really?  So you are saying that the 20-degree difference in delta-T results in a miniscule difference of heat transfer?
Really?
The delta-T between inside and outside has a miniscule effect on the energy lost to the outside?
So, for example: It is 20 degrees outside.  House A is being maintaned at 50 degrees internal temperature. House B is being maintaned at 70 degrees internal temperature.  House A and B are identical in every other way.  The difference in their energy use is miniscule?

and you will suffer more loss trying to put BTUs back into the MASS afterwards that you will have saved. At least when talking about over a 24 hour period. Totally different story if you're going away for two weeks and turn it down while you're gone. Again, think of it like driving your car. Which driving gets you better gas mileage, highway cruising or city stop and go? It's the exact same thing!!

Well city stop-and-go is much less efficient, we all know that.  It's like power-cycling your furnace between 72 and 70 degrees all day.
Highway driving is much more efficient, like running your furnace for an hour at the end of the day to bring the temp back up.
Thanks for proving my point.
Twice.

[280plus]

One of these things is not like the other. Which is it?

By your second statement, if you have to replace the lost thermal energy "BTU for BTU" (and I agree that you do) then even if you saved NOTHING from the reduced DeltaT (and you admit that you do save) then it couldn't possibly cost more, by your own reasoning.

By your first statement...well, I can't think of a physical principle that would allow it to be true.

Look, quit grasping at straws trying to come up with some way to prove me wrong. As I stated long before I tried to explain this, all I can give you is the benefit of my 30+ years of working in the heating and A/C business, you are getting this advice/explanation for free, at least twice now in as carefully worded a manner as I can. Take it or leave it. You don't want to believe me and want to try to poke holes in what I am saying rather than accept this advice, fine by me. :)

I'll ask you this one more time and then I am done. Do you get better gas mileage mile for mile driving stop and go in the city or cruising down the highway? Third time: IT"S THE SAME DAMN THING!!

[280plus]

Yes, that is what I am thinking.  Glad you agree as well.Really?  So you are saying that the 20-degree difference in delta-T results in a miniscule difference of heat transfer?
Really?
The delta-T between inside and outside has a miniscule effect on the energy lost to the outside?
So, for example: It is 20 degrees outside.  House A is being maintaned at 50 degrees internal temperature. House B is being maintaned at 70 degrees internal temperature.  House A and B are identical in every other way.  The difference in their energy use is miniscule?
Well city stop-and-go is much less efficient, we all know that.  It's like power-cycling your furnace between 72 and 70 degrees all day.
Highway driving is much more efficient, like running your furnace for an hour at the end of the day to bring the temp back up.
Thanks for proving my point.
Twice.

Fine, you win, you are waaaay smarter than me, I bow humbly to your superior knowledge. You go ahead and do things your way. 

[Jim147]

With the temp swings of using the setback you have to take into consideration the comfort factor.

If you cool off the whole house then warm it back up, even after the system shuts down, the walls, furniture etc. are absorbing heat. What this feels like to humans is described as feeling chilled or drafty. If you are standing next to a cold wall in a room that has warm air you will not feel as comfortable. So you go and bump the temp up a couple degrees to knock the chill out of the house. More frequent cycles and running the heat higher for a period remove any benifit of the setback.

A lot of stuff plays into this of course like the insulation in the house and quality of the windows. A tighter house won't have as short of swings and won't get that drafty feeling like a leaky house.

FWIW, YMMV, blah blah blah :)

This reminded me of the real problem I was having.

Comfort. It is hot and humid here in the summer and cold and dry in the winter. When I used to turn the A/C up in the summer the hot humid air would infiltrate the house during the day. The humidity adds a huge load to the A/C to bring the house back to comfortable.

Same thing in the winter. My warm moist air in the house is escaping to the dry cold air outside. So if I turn the heat down much I have to replace the heat and the humidity to make the house comfortable again.

Like Ron said, if you have a tight, well insulated house in a more moderate climate, you don't have to deal with the same problems.

jim

[AmbulanceDriver]

280, I have a question along the same lines here, regarding setback, etc.

We've got an approx 1800 sq ft house...  it's an older house, built in 1969.  We've got no exterior wall insulation except in the 400 sq ft addition (family room).  Forced air gas heat, about 15 year old furnace (we think, based on maintenance stickers on the side of the thing....)  The attic has some (maybe 6 inches, maybe a little less) blown cellulose insulation in the attic.  No insulation in the crawlspace.  Ducts are wrapped with insulation and foil...  We recently replaced all our old wood/single pane windows with new vinyl low-e windows, and are planning on tackling the insulation after we rewire the place.

Currently, we take the heat up to 68-70 (depends on how cold we're feeling, but more likely up to 70) in the evenings after we get home from work.  When we leave, we take it down to 63, as well as at night when we go to bed.  We like the slightly cooler air temp at night, and just cover up with blankets, etc. 

Should we be sticking to that 4 degree setback, or are we OK going to that 6-7 degree setback?

[280plus]

AD, what you should be concerned with is the temperature of the mass. If you can find a way to accurately measure the temp of the walls, (both inside walls and walls exposed to the outside), any masonry you have like a fireplace and maybe the kitchen counter. Check a few spots. Find out: A. What the surface temp is just prior to going into setback, B. what those temps are as the system comes back out and C. how long it takes for the mass to return to the upper setpoint after it comes out of setback. What you want to see is these mass temps returning to the upper setpoint within about an hour of coming out of setback. If so you may be saving a bit. If you find that the mass temp is NOT reaching upper setpoint for several hours after coming out of setback you will be spending more $ to reheat the mass then you have saved by setting back. I never said setting back is a BAD thing (especially on older single stage equipment) I'm saying TOO MUCH setback is a bad thing for reasons I tried to lay out in the long winded posts. Every house is different so it's tough for me to say exactly what the optimum setback is for yours but I believe you can determine that and dial it in for yourself using the above method.  That said, I like the rule of thumb 4* so I suggest trying it there first and tweaking accordingly. Remember, it can take days for an adjustment to settle out, so tweak and then wait a day or so before you do your readings again and determine whether you want to try a little more or a little less. PLEASE try to remember to post your results here.


I'll repeat this again, if, after an hour or so, your mass temp does not equal desired air temp the result will be that for a long period of time the air being warmed by the system will be cooled back down more quickly due to the lower mass temp surrounding it and result in more run cycles through the period it takes to get the mass back up to desired air temp, IF IT EVER DOES. 

Again, I have seen a case where, with a 55* setback at night the mass of the building was still only 56* at 2 pm in the afternoon at least 6-8 hours after coming out of setback. It takes FOREVER for the mass to warm back up, DAYS. That's why it doesn't make a lot of sense to lose all the heat it took to bring the mass up to temp just so you can do it again later. Again with the car analogy. Does it take more gas to accelerate to 70 mph or cruise at 70 mph? Think of warming the mass as accelerating and once it's reached desired setpoint you are cruising.  if your desired speed was 70 with optimum gas efficiency would you be decelerating to 55 and re-accelerating to 70 regularly on that trip?

My suggestion to you is do whatever you can to insulate as much of your house as you can. definitely add at least 10" to the attic and, if I understand you correctly the floors are uninsulated and exposed to outside air temp? There is your biggest loss right there. Find a way to get under there and insulate. Poking holes in the walls and adding there isn't a bad idea either but much more labor and cost intensive. Hope this helps.

[280plus]

Afterthought...

I believe you'll get best data wit a digital thermometer that reads down to tenths of a degree. and a contact probe. Insulate over the probe so you get surface temp not a combo of surface and air. A handtowell folded up is probably sufficient. Don't place your hand over it to hold it in place while you're reading.

I'll look around for a cheapie later and see if I can find anything.

[280plus]

I'm thinking I want one or two of these myself. If you have trouble getting them from Grainger let me know and I can order you one and have it shipped to you.

http://www.grainger.com/Grainger/EXTECH-Digital-Pocket-Thermometer-1BP95?cm_sp=IO-_-IDP-_-RR_VTV70300505&cm_vc=IDPRRZ1

Always use the same thermometer for all readings. No two will read exactly the same, at least in the cheapie dept.  Actual accurate temp is not as important to us as the accuracy in reading the differences. naturally you should take the air temps in the various areas as well and if you're REALLY ambitious take readings above the ceiling and below the floor and compare them to their respective surface temps. Outside air temp to in relation to outside wall temp. My thought is outside walls, ceiling and floor will NEVER reach indoor ambient temp, especially without insulation.  How long does it take the kitchen counter, walls, floor, etc to recover to pre-setback temp? Does it ever recover?  If the mass inside never reaches desired occupied temp you're basically always playing catchup when you come out of setback.

Another analogy, lol, ever hike in hilly country? Do you get to the point where you hate topping a big hill only to see a nice downward slope with another big hill to climb just afterwards? So does your energy bill.

It reminds me of these two guys I met on the AT coming up from TN.  They hated NY and CT so far cause no sooner did you climb one hill you went down and had to climb another, and the farther you get north, the bigger the hills get. 

[CNYCacher]

The car analogy is fatally flawed as soon as you start talking about miles per gallon because because there is no way to translate miles per gallon to anything meaningful in a home heating scenario.

The only meaningful measurements are energy used per unit time.  For a house, the energy used per unit time is dependant upon the amount of energy leaving the house for a given temperature delta between inside and outside.  For a car, the energy used per unit time is dependant upon the speed delta between the air and the car.  The faster you go the more fuel you are burning per hour.  You need a certain amount of energy per hour to maintain a house at a particular temperature and you need a certain amount of fuel per hour to maintain a car at a certain speed.

Miles per gallon is a ridiculous ratio to bring up as an analogy.  There is no household heating equivalent to miles per gallon, the house isn't going anywhere.  The faster you travel in your car, the less time a task takes to accomplish (traveling a mile).  What is the travelling a mile in house talk?  What task is performed faster be the home being warmer?  Nothing.

If you insist of comparing houses to cars, then you need to drop the idea of miles per gallon, and start talking about gallons per hour.  How many gallons per hour is the car burning while traveling 70mph?  How many cubic feet of gas per hour is the home using while maintaining 70 degrees?  How many gallons per hour is the car burning while driving at 50 miles per hour?  How many cubic feet of gas per hour is the home using when maintaining 50 degrees?

So, now that we got that cleared up, lets talk cars.

The question is this:  I need to ride in my car for 24 hours (not for so many miles).  How do I save fuel?  I need to be doing at least 70mph so I don't get bored with the scenery (human comfort factor related to temperature in the home) between 12 am and 8am.  I then exit the car for 8 hours and don't really care what speed it travels at while I am gone, but when I get back it should be doing at least 70 for the rest of the day.

CNY Solution: Since the car uses more fuel per hour at 70 mph due to increased air resistance (thermal transfer through exterior walls), have it slow down to 50 while you are gone, then speed up to 70 when you come back.

280 Solution: Only let the car slow down to 66.  You aren't thinking of the mass of the car.  It has a lot of mass.  Once the car gets down to 50mph, you are going to use more energy accelerating it back up to to 70, than you would if you just maintained it at 70.



You seem to think I am ignorant of the thermal mass in a house.  Whatever.  You decry the energy needed to warm the thermal mass, but you seem to think that the energy in the thermal mass just vanishes while the thermal mass cools.  The amount of energy needed to warm the thermal mass is exactly equal to the amount of energy you didn't have to spend keeping the house warm as the thermal mass cooled.

[280plus]

Whatever dude... I have neither the time nor inclination to read any wall of text. Thanks.

But I will go as far to say you're argument is fatally flawed because you fail to equate energy with energy in the analogy. Why SHOULD I read any further?

[Harold Tuttle]

i know in winter i gave up on any significant set backs on my home heat pump, as it took forever to come up to temp
it seemed the HP ran once an hour for 15 minutes to maintain 68 degrees but getting it from 64 to 68 had the unit running from 5 till 7 pm

I am much happier with my new house and its gas furnace.

[CNYCacher]

Whatever dude... I have neither the time nor inclination to read any wall of text. Thanks.

But I will go as far to say you're argument is fatally flawed because you fail to equate energy with energy in the analogy. Why SHOULD I read any further?

Says the guy who is talking about miles per hour as if that's meaningful.

Just read it.  I'll pay you your standard rate for your time if that's what it takes

[Kingcreek]

Sure has been interesting and informative to read this thread...
but mostly, I'm just really glad I have radiant heat instead of forced air convection heat.