Lost Electricity -2

Most thermostats also have an "anticipator" setting. They will stop calling for heat when the room temperature gets close to the set point. The objective is to prevent the room temperature from oscillating above the set point due to residual heat being released into the room by radiators. It's not usually an issue with hot air systems because they warm the air directly. But hot water, steam, and radiant electric systems usually need it. If you have a hot air system and the anticipator is engaging as if it were a hot water system, that could account for having it cut off too soon.

Reply to
Elmo
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the

No post (at least that I saw) claimed that setting the thermostat up increased the rating of a standard residential hot air furnace.

Reply to
Ann

Claiming that setting the thermostat higher than the desired temperature will cause the room to reach that temperature faster is _exactly_equivalent_ to claiming that setting the thermostat higher than the desired temperature will increase the output of the furnace. :-)

Reply to
Doug Miller

The point is that different parts of the house heat up at different rates, because they have different heat capacities. Air has a low heat capacity, so it heats up quickest. Denser parts of the house, e.g. drywall, concrete or plaster, heat up more slowly.

In the usual case, a furnace is just trying to maintain a set temperature. The heat loss to the outside will be fairly constant, the temperature differences between different parts of the house fairly small, and the different rates (heat capacities) of the building materials not so important.

But if the house starts off "cold", say everything at 50 degrees, and you want to raise the temperature significantly, say to 70 degrees, then the different heat capacities have an effect. If you set your furnace thermostat to 70 degrees, it will shut off when the air around the thermostat reaches 70 degrees. Other parts of the house that have higher heat capacities will not have reached 70 degrees yet, so they will continue to absorb heat and cool the air down.

That is, even though the thermostat shut off, the average temperature of all the materials in the house is not yet 70 degrees--only the air temperature is at 70 degrees. As the cooler parts of the house continue to absorb heat from the air, the air temperature will drop and cause the furnace to run again to bring the air temperature up to

70 degrees. This process will repeat until all the materials in the house reach 70 degrees.

Now if you initially set the thermostat to 80 degrees, and then reset it to 70 degrees, you will initially overshoot your target temperature by 10 degrees as far as air temperature. But at this point the average temperature of the materials in the house will be closer to 70 degrees. You will reach equilibrium with everything at 70 degrees sooner.

Cheers, Wayne

Reply to
Wayne Whitney

So, who wrote that" (Hint: It wasn't me.)

Reply to
Ann

Thanks to all who have thought on this and offered your opinions. What I've concluded so far is that this is not just my problem. At least 10 neighbors experienced the same thing. This tells me that it isn't just a leaky extension cord. A 20% reduction in the # of days with electricity means that on the days I did have power I would have had to use 20% more each and every day to maintain the monthly average of the previous 5 years. I was indeed 10% colder for the month of DEC 07 than average, but heating is a small part of our (collective) electric usage. the neighbors heat with LP, Oil , wood, or corn none use electric heat or heat pumps. Someone mentioned higher voltage being pumped through the lines. Does this make sense to you who are not electrically challenged? How about more Hz? My plan now is to gather more anecdotal evidence (oxymoron?) and question the REC on Monday.

  1. Did they estimate Dec's reading. (or other months)?
  2. What could have caused this average monthly (31 day)usage when we were all without power at 20% of the time? Further thoughts and notions appreciated. Steve Southiowa

----------------------------------- Steve, Same problem here in NE oklahoma. I live on a dead end street, 20 houses, everyones bill went up. We were out of power from the 9th of december to the 18th of december. I left town on the 22nd. of december turning all power off. got a 137.00 bill for december, previous month was less than 60 bucks. I went to my REC and they gave me the biggest BS I've ever heard. I finally said, dont piss down my back and tell me it's raining, and left. BTW 15 to 20 other irate customers in the REC lobby wanting explantion of their bills. I've got a complaint in to the Corporation Commission, and wrote a letter to the local liberal rag. You aint wrong, their hosin us. My REC lost 1500 poles and now they want us to pay for it in one month, BS. I shut off all breakers except for the front room recepts, one lamp and TV/webtv. wonder how they'll justify screwing me next month. My walls are 14 inch thick, brick and concrete. i live by myself, and took my wash to the laundermat when out of power. I have baseboard radiant heat and have thermostats in each room. the 2 spare rooms, I close off and never heat and cool. leaving only the master, which i keep cool in the winter and the front room/kitchen less than 800 sq. feet. yeah, were getting screwed. Mike

Reply to
The hooligan

At which time the furnace will come on again.

No, you won't. Not unless you've discovered some new laws of thermodynamics.

Reply to
Doug Miller

it is called heat transfer. more heat in air at 80 will put more heat into the walls, getting them up to 70 faster. You won't save energy, you will save time. But, the heat loss out the windows will be greater with a temp up to 80.

Reply to
Gil Faver

In article , "Gil Faver" save time. But, the heat loss out the windows will be greater with a temp

Any difference there might be would be far too small to be noticed. Were you imagining that heat transfer at 80F is 14% faster than at 70F? Doesn't work that way. Use absolute temperatures.

Reply to
Doug Miller

the

for heat when the room temperature gets close to the set point. The objective is to prevent the room temperature from oscillating above the set point due to residual heat being released into the room by radiators. It's not usually an issue with hot air systems because they warm the air directly. But hot water, steam, and radiant electric systems usually need it. If you have a hot air system and the anticipator is engaging as if it were a hot water system, that could account for having it cut off too soon.

It was probably the heat anticipator that caused the situation I described (furnace shutting off too soon).

Now, If I had access to that house in the last 20 years, I might know what needs fixing. I haven't seen it where I'm now (same type of furnace).

Reply to
Mark Lloyd

No it isn't. Don't forget about run time.

In this case, we turned on the heat in a 50-degree house, with the thermostat set for 70. The furnace cut off when the temperature was about 60. Each additional heat cycle would raise this some until it got to 70.

Reply to
Mark Lloyd

hey, this tread long ago drifted off into the theoretical natty gritty. Don't blame me! ;)

faster is faster. I think we agree on that. I think we also agree on "who cares - put on a sweater".

Reply to
Gil Faver

Umm, my understanding is that for convection and conduction, heat transfer rate is proportional to the temperature difference. So there is a big change in heat transfer rate for 70F versus 80F air. [E.g. for 60F building materials, the temperature difference is double with 80F versus 70F air.]

Look at the original question this way--you want to get the average temperature of a building from 70F to 50F. Based on all the different materials and their heat capacities, this will require some number of BTUs; based on the furnace output rate the furnace will have to run some number of hours to put out the required heat. Say 2 hours.

Air temperature will be a leading indicator of average building temperature. So if you set your thermostat to 70, the furnace will run less than two hours, then it will cycle on and off for a while as the building catches up to the air temperature, until the total running time reaches two hours. Or you could set the thermostat artificially high for two hours and then reset it to 70 degrees. The two hours of furnace time required occurs all at once.

Clearly the latter strategy causes the building to reach equilibrium sooner. That's all I'm claiming, not that it is a good idea, will be more comfortable for the occupants, or that it is more efficient.

Cheers, Wayne

Reply to
Wayne Whitney

According to The hooligan :

No neither would explain it. Voltage or hz changes big enough to have this big an effect on your billing would almost certainly have caused damage to some of your or your neighbor's equipment, and would probably have been visible during the time.

Actually less hz means more current to inductive devices like motors, and more hz means less current. hz changes won't do _anything_ to pure resistive devices.

With many devices, when you raise the voltage, the current doesn't increase at the same rate, and in some cases even declines. In a pure resistive device, a 10% increase in voltage comes with a 10% increase in current -> 21% in watts. However, many devices in a home don't behave that way. Even incandescents significantly change resistance as the voltage goes up (filament gets hotter). In other words, V/I isn't a constant in incandescent bulbs or resistive heat strips.

I'm more thinking of a processing error in their billing cycle. If you know what the before/after readings were (directly from the meter) compare that to the bill. It's remotely possible that when presented with a big gap in the data flow, the billing software gets confused - eg: a negative increment instead of a positive. Who knows, perhaps the meter electronics forgot something while they were unpowered _that_ long.

You seem to be lucky that your utility is also interested in understanding what's happening. Keep working it - they will want to figure it out.

Reply to
Chris Lewis

No one claimed that doing so would cause the room to reach temp sooner. I was claiming (and maybe Ann was as well) that doing so would allow the room to reach the desired temp with fewer "cycles" of off/on.

I'll try again to explain. If I want my house at 70, I might sent the t-stat to 80. The furnace comes on, then cycles off as the air near the t-stat is 80. As the heat in the air warms the rest of the stuff, its temp drops, and the furnace cyles on. Once the system has done this a few time, I reset the t-stat to 70.

If I had set it at 70 and left it there it would have reached equilibrium at roughly the same time, but while it was doing so, the temp in the house would have been

Reply to
Charles Bishop

According to Neon John :

Nit-pick: four state: off, refrigeration/heat, defrost (self nitpick: via controller) and supplementary heat.

The supplementary heat doesn't _have_ to be resistive. Ours (in a previous house) wasn't. If we go HP again, it won't be.

Ours (with gas backup) had two sensors. I don't think it did a lot of smarts with them, but it was remarkable how low the heating/gas bill was, even in the great white north.

Reply to
Chris Lewis

That indicates a defective thermostat, which renders the example meaningless.

Reply to
Doug Miller

Or one not leveled properly, if it is an old Honeywell mercury-switch deal.

nate

Reply to
Nate Nagel

But if you overshoot (keeping it set to a higher air temperature) and then set it back to your true desire and let the room "soak" you might reach equilibrium faster.

Reply to
CJT

^^^^^^^^^^^^^^^^^^^^^^^

Focus on this bit for a minute instead of the bit you've been focused on. What is "the room?" It's not the thermostat and it's immediate surroundings. What is "reach?" It's not the first time you're asymptotically within a delta -- it's when you've established it with some stability.

Reply to
CJT

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