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cuemaker
12-12-2005, 09:37 AM
I moved into my new house over the weekend. And damn, I have a lot of sh**. It took 4 grown men 4 women 2 days. Either I am not moving or I am paying someone next time.

And I haven't even moved my garage or my basement office/some junk in the basement yet!!!!!!!!!!!!!

Anyways, here is the point of the post.

Father in law says...... " it doesn't matter if your thermostat is at 65 or 70, after the house in initially heated, it takes the furnace the same amount of gas to keep the house at any temperature"

Now, before he said that, I was of the mind you keep the thermostat lower to save on propane.

But now he seems kinda right. When the heater kicks on, its only gonna run until it brings up the room that the thermostat is in up to the setting, whether its 70 or 65.

For the sake of the discussion, lets assume a newer house, with standard to good insulation using propane to heat a house.

Thanks

SGW
12-12-2005, 09:43 AM
No, the rate of heat loss depends on the temperature differential. Energy wants to flow downhill. The bigger the temperature difference, the steeper the hill.

cuemaker
12-12-2005, 09:54 AM
so in layman's terms, the rate of heat loss is higher for a warmer house, so therefore the heater is gonna kick on more to make up the difference.

Does 5 degrees make that much difference?

meho
12-12-2005, 10:34 AM
It takes less heat to maintain 65 than 70. All things (insulation) being equal. The saying is one degree is one percent of the gas bill over the year. I don't know how accurate that is though.

Insulation and air infiltration are the biggies here. Most of the heat loss is lost through the attic.

I use programable stats at home. They keep the house 68 from 4PM to 11PM then sets back to 63 for the rest of the night.

James

Evan
12-12-2005, 11:08 AM
Heat loss happens as the square of the temperature difference. So five degrees makes a big difference.

lynnl
12-12-2005, 11:24 AM
So, is that to say that maintaining the extra 5 degrees results in 25% higher (than baseline) heat loss? ...or 25% of the additional heat energy is lost?

Does this take into account the eider-pinion effect?

Evan
12-12-2005, 11:32 AM
The actual loss depends on the temp difference. If you are doubling the temp difference the heat loss goes up 4 times.

We use the eider-pinion effect to good advantage at our house. We both sleep under individual eider down comforters, extra large size, that we picked up in Denmark.

One thing we did years ago that saves a bundle is to buy individual chair size electric blankets for our chairs in the living room. These are designed to sit on as a throw cover for the chair. We can turn the heat way down and still be comfortable. We just have to remember to turn it up when we have visitors.

J Tiers
12-12-2005, 01:36 PM
<font face="Verdana, Arial" size="2">Originally posted by meho:

Insulation and air infiltration are the biggies here. Most of the heat loss is lost through the attic.
</font>

When we replaced the leaky steel-frame basement windows with glass block, the winter temp in the basement went up at least 10 deg, without any other changes. That's with only 4 standard basement windows......

And the ground floor is a bit warmer too.....

leakage hurts.

Evan
12-12-2005, 02:10 PM
What I want to know is how can it get to -40 degrees here on the surface when the overwhelming majority of the earth is at 2000 to 13,000 degrees.

3 Phase Lightbulb
12-12-2005, 03:24 PM
<font face="Verdana, Arial" size="2">Originally posted by Evan:
What I want to know is how can it get to -40 degrees here on the surface when the overwhelming majority of the earth is at 2000 to 13,000 degrees.</font>

Earth's crust is a great insulator...

I've been thinking about running water pipe under my driveway the next time I redo it.. In theory if I circulate water from my well, through pipe in my driveway, and back into my well that will keep the driveway surface warm enough (40?) to prevent snow from building up. Maybe add an inline electric water heater if that doesn't fully prevent snow buildup.

wierdscience
12-12-2005, 10:26 PM
<font face="Verdana, Arial" size="2">Originally posted by 3 Phase Lightbulb:
Earth's crust is a great insulator...

I've been thinking about running water pipe under my driveway the next time I redo it.. In theory if I circulate water from my well, through pipe in my driveway, and back into my well that will keep the driveway surface warm enough (40?) to prevent snow from building up. Maybe add an inline electric water heater if that doesn't fully prevent snow buildup.

Several people here have done similar,but in reverse.Using the driveway as a solar collector to heat the swimming pool water.500'poly tubing under the drive and a circulating pump does the trick.
Maybe plumb the thing to do double duty.

Kansas_Farmer
12-12-2005, 10:39 PM
Steam is where I want to be. 50Hp boiler, run say, 135-150 psi, turn a 30-35kw genny. In the winter, exhaust is piped to radiators in the house, under the driveway and then back to the feed water tank. In the summer, we just dump it out the stack.

Fuel for this thing would be primarily corn, but could burn about anything if it needed to. Add in a pump and nozzel and I'll feed it waste engine oil at the same time.

Make it all automatic with computer control and we are done.

Lots and lots of wishful thinking here I know..

lugnut
12-13-2005, 12:40 AM
When all these guys are done with their analysis of their opinions, go and buy a programmable thermostat. One that you can set the temperature for at least four sections of the 24 hour day. Morning, daytime, evening and night. Pulse a weekend setting for Saturday and Sunday. You can then set it up to bring up the temperature just before you get up in the morning , say 70 then maybe drop it to 68„a for daytime and evening. Then down to 63 or 65 for night. Might want to delay the wake up temp on the weekends or when not at home. I have had one for the past 5 years and would not be with out one.

[This message has been edited by lugnut (edited 12-12-2005).]

HTRN
12-13-2005, 03:09 AM
Putting tubing into driveway's so they can keep them snow free is pretty much common around here for new construction of \$\$\$ houses. If I was to do over my driveway, I'd sure as hell do it. Most are using hot water from a boiler to keep the concrete warm. I don't think Ground water temp (around 50F actually) would be warm enough to do it, especially in the middle of a cold snap.

I would suggest to anyone who has a well and is looking to replace a furnace to strongly consider a geothermal heat pump. Much cheaper to run than other systems as you get the "heat" for free - you only pay to extract it. Requires electricity to operate the pump. Now here's where "strategery" comes in. Find out if your state requires the electric companies to "buy back"(at the same price charged!) electric from homeowners who generate power through Solar/wind/etc. If they do, get some solar panels and wire 'em into your household grid - if you have enough of them, you'll be able to heat and cool your house for free.

HTRN

------------------
This Old Shed (http://thisoldshed.tripod.com)

chief
12-13-2005, 06:47 AM
It depends on whether or not you leave the refrigerator door open or not.

12-13-2005, 06:52 AM
Cuemaker: I think your Father-in-law is wrong. It sounds good but don't work that way. Here in the Buffalo area we have a lot of folks who winter in florida. They mostly set their thermostats in the mid 50's. There is a point of deminishing returns on the setback according to energy experts. Set it too low and you get little benefit from it. Ask your local gas company why they reccomend setting your thermostate back to save money. They'll tell you it takes less energy at the end of the day to heat the house from 65 to 70 once or twice a day then it does to keep it at 70 all the time

3 Phase: You just re-invented a heat pump. If the temp outside your home is 10 degrees and the earths temp is constant 50 degrees than you are getting your first 40 degrees of temperature elevation for free (nearly) and only pay to go from 50 to 70. Same principle applies to air conditioning in Summer.

Evan: I setback to 45 on the key lock thermostat and I threw away the individual eider down comforters, it's the only way I can get a little and then only during the cold winter months http://bbs.homeshopmachinist.net//biggrin.gif The upside to that is you really get to like Winter.

HTRN: I'm told you can't use your well for that purpose. I was also told they normally drill 4 wells for an average home installation as the capacity for each well is small compared to the needs. I'd rather take the money and move to Florida and live in a waterproof concrete bunker on high ground http://bbs.homeshopmachinist.net//biggrin.gif

This message has been massaged

[This message has been edited by Your Old Dog (edited 12-13-2005).]

winchman
12-13-2005, 03:02 PM
Here's a formula and calculator for heat transfer through a wall:
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatcond.html

Just enter the info and get the answer.
Roger

J Tiers
12-13-2005, 05:29 PM
If you have a house with a low thermal mass, it will heat up faster, and not use so much at the end of the day....

If you have a brick house with heavy plaster walls, it will take more to heat up.

On teh other hand, if the house is colder, it loses heat slower, so you run the heater less to maintain the lower temp.

Either way it should amount to the same thing, the heavier house may have the heat on less during the colder setting.

If it is really cold out, like -40, it may make relatively little difference in the rate of heat flow if you are at 65 vs 70 (if your furnace can even do that). If it is relatively warmer outside, there might be a much bigger difference.

Still may be significant to you, but percentage wise it is far less the larger the overall difference.

I have a heavy brick and plaster house, with hot water heat (the best, btw). It does make a difference in the bill, but it takes a while to heat back up.

bob308
12-13-2005, 05:52 PM
if you think your house is cold stand out side with no coat for half an hour then run in. it will feel real warm in there.

bob308
12-13-2005, 05:52 PM
if you think your house is cold stand out side with no coat for half an hour then run in. it will feel real warm in there.

Alistair Hosie
12-13-2005, 06:13 PM
Easy answer if you feel cold turn it up til you feel nice and warm if you feel warm keep turning it down a lil til you feel nice and not too warm no need for technicality the good lord provided you with an inbuilt thermostat.Alistair

andy_b
12-13-2005, 08:24 PM
<font face="Verdana, Arial" size="2">Originally posted by Evan:

One thing we did years ago that saves a bundle is to buy individual chair size electric blankets for our chairs in the living room. These are designed to sit on as a throw cover for the chair. We can turn the heat way down and still be comfortable. We just have to remember to turn it up when we have visitors.</font>

i can just envision Evan and his wife lounging under their electric blankets with ice on the windows.
http://bbs.homeshopmachinist.net//smile.gif

i could actually live like that, as long as i had a heated toilet seat.

andy b.

spope14
12-13-2005, 10:10 PM
The rule I heard recently was 2 degrees per hour. This is heat loss, and heat gain for maximum effect. Makes sense. At night, drop off 2 degrees at a time throughout from say 70 to 66. Hold at 66 throughout, Then return back to 70 by morning wake-up. This cycle is suggested to start one hour before normal bed time, and when off to work doing the drop, and the return back up. More on the "drop off" effect and importance at the end of the next paragraph, sounds strange, but is valid.

The next thing is furnace "Balance". Oil heat furnaces are "balanced" here in New England to hold 70 degrees inside temp while out side temp is zero degrees F. This is actually in effect with me tonight, -5 outside right now. I used to get killed when it would hit -25 at night, and -10 for a high temp during the day, my furnace would be burning out straight to hold 68 degrees in the house and maybe 66. Nothing to do with insulation, just the "high and low" limit temps of the furnace water circulation temps. The solution is this, tried it three days back, working at -5 right now. The furnace man and the heating techs I deal with noted to kick up the high limit by five degrees, thus at -10, I can still hold temp inside at 70. My wife is diabetic, advanced stage, so temp is important to me as she gets cold easy (I could hold the home at 60 for my life....). We have been -5 to -10 at night for four days now, holding temp at 70 easy, and less fuel burn. The "drop off" thing comes into play here. If stuff including circulated water in the home gets too cold during really low temps for extended periods of time, then needs to be re-heated to a high temp, it takes many hours compared to few. Items in the home will hold higher temps for longer than the air temp holds it. The air temp increases but your large items such as beds, walls, sofas, closets stay cold, they radiate cold. Sounds like BS, but it really is something to consider, as i used to jockey temp 8 to 10 degrees at night, and I could really feel cold radiance from these items.

One final thing, Our oil guy, who is looking for ways to save his fanny because he got shafted in the pre-buy sales (sold off pre buy for rediculous price, then the big hikes hit), suggests keeping temps a bit higher during deep cold snaps. He really wants to save oil because every gallon he delivers right now at the price I bought in at costs him about .30. I want to save gallons because i am just plain cheap. I am trying, and have been burning the same 250 gallon tank since August, where before I would buying tank three at this time.

Each home is different, as is each system.

[This message has been edited by spope14 (edited 12-13-2005).]

Evan
12-13-2005, 10:15 PM
There is only a little ice on the double glazed sliding glass doors. It isn't that cold, yet. I think I'll go start a fire and make some chips. My shop is near the wood stove. http://bbs.homeshopmachinist.net//smile.gif