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Five Star

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Discussion starter · #1 ·
Was at a family members house over the weekend and they are sitting in a huge 4000 sq ft house with the Thermastat set at 68 degrees when its 30s outside and a Guard watching the thermastat, when ever any one approaches she grouls and barks:cursing:

My Question is, If a homes temperature is reached and set ,the thermastat kicks on when it drops a degree,and stops when it reaches its set degree, Does it matter if room temp is 68 or if its 72? Is The Furnace Working Any Harder Or Burning More Fuel to gain a degree ?? Once Temp is Reached??

And yes i realize going from 68 to 72 uses more energy and fuel!! im just talking about leaving a thermastat set at the desired temp?
 
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#3 ·
I'd say that the higher the temperature differential, the harder it will be to maintain that differential. Think in terms of air conditioning. If you keep the t-stat at 70 and the outside temp is 80, there is not a great deal of load on the unit, assuming it is sized properly.

As the outside temperature climbs, the load increases, until at some point, the unit will not keep up and will run constantly.

I would think the same has to work in reverse.

Insulation only slows the transfer of heat, it doesn't eliminate it.
 
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#4 ·
I was also wondering about that and then I read a very interesting article about energy conservation and how things work and why, then after reading that, I spoke to my neighbor who teaches physics in college, and after he explained to me, I learned the following.

Any change of temperature of air produces a change equal to 1/491 part of its volume, for each degree variation. So if a cubic foot of air is raised in temperature 1°F, its volume will be 1/491 part larger than the original volume, and its upward force in the surrounding air will be increased correspondingly.Since there will be a greater change of volume, warm air tendency to rise will increase 1/491 for each degree difference in temperature and the upward velocity of heated air will be very large and the warmest air will rises to the highest point and the air will escape the home much faster, then cooler air, making the heating system run more frequently. This is why thermostats pre-programed to 68 degrees, and suggested comfort level for inside the home is about the same, because for each degree below 74 degrees (I will not go higher) during the colder weather, you gain as much as 3%-5% savings in energy costs.

So if your relatives have a 4,000 SF home, and I will assume they have a 2 zone heat... and if they keep 68 degrees vs. 74 degrees that will be 6 degrees per unit X let's say 5%, they can save about 60% on heating cost a month. So if they have an average bill about 400-500 at 68 degrees or lower, at 74 it will be $700 +

I hope this helps :thumbsup:
 
Discussion starter · #5 · (Edited)
Greg, i see your piont, But the question is not going from 68 to 74!!

I just think that if a one zone first floor lets say, reaches a temp 68 or 72 once the temp is reached, the system cycles when the house looses a degree the system runs to get back to its setting!! ts gonna run regardless as the temp out side drops, so if they keep the temp @ 72 and its in the 20s out its not using more flame or gas as if its trying to hold the house at 68!!

The the energy or fuel consumption is the same to get back a degree or 2,

going from 68 to 74 is obvouisly gonna make the system just run and not cycle!

So why pay the same bill +/- a few dollars and suffer @ 68 when you can keep it a comfortable level 70 -72 (obviously its a preference whats comfortable) so kids and guest dont need 3 layers of clothes!! and leave the thermastat to do its job...$ for $ ! i understand when you leave for work the timer helps if your out for 10 hrs, thats a different topic!

2-4 degrees is not gonna be 60 % more on the heating bill!
 
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#6 ·
greg24k said:
I was also wondering about that and then I read a very interesting article about energy conservation and how things work and why, then after reading that, I spoke to my neighbor who teaches physics in college, and after he explained to me, I learned the following.

Any change of temperature of air produces a change equal to 1/491 part of its volume, for each degree variation. So if a cubic foot of air is raised in temperature 1°F, its volume will be 1/491 part larger than the original volume, and its upward force in the surrounding air will be increased correspondingly.Since there will be a greater change of volume, warm air tendency to rise will increase 1/491 for each degree difference in temperature and the upward velocity of heated air will be very large and the warmest air will rises to the highest point and the air will escape the home much faster, then cooler air, making the heating system run more frequently. This is why thermostats pre-programed to 68 degrees, and suggested comfort level for inside the home is about the same, because for each degree below 74 degrees (I will not go higher) during the colder weather, you gain as much as 3%-5% savings in energy costs.

So if your relatives have a 4,000 SF home, and I will assume they have a 2 zone heat... and if they keep 68 degrees vs. 74 degrees that will be 6 degrees per unit X let's say 5%, they can save about 60% on heating cost a month. So if they have an average bill about 400-500 at 68 degrees or lower, at 74 it will be $700 +

I hope this helps :thumbsup:
Click to expand...
greg24k, When I first read your post I thought maybe you were practicing your speel to sell ice cubes to Eskimo's:whistling. However it is really very well stated.:thumbsup::clap:
When the prof was explaining were you thinking why did I ask this guy this question?:laughing: Cheers Griz
 
Discussion starter · #7 · (Edited)
I think he had the professor type it into his laptop ;)


You only save 10-12 percent so on a $500 average bill your saving $50 ! if the savings was say 20 - 40% more, id turn my thermastat to 50 degrees to keep the pipes warm and talk to you guys in my ski suite
 

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Discussion starter · #8 ·
http://greenhomeguide.com/know-how/article/keeping-warm-for-less

Image
Lower the Thermostat

Each degree you lower the thermostat on your heating system decreases your fuel bill by 3 percent. Going from 72 degrees down to 68 degrees doesn't matter much in terms of comfort, but it can save up to 12 percent on your heating bill. (All temperatures in this article are in degrees Fahrenheit.)
If you're using a coil-type thermostat, you'll get more accurate readings if you clean it. Pop off the thermostat cover and blow or gently swipe away the dust.
 
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#9 ·
Five Star said:
http://greenhomeguide.com/know-how/article/keeping-warm-for-less

Image
Lower the Thermostat

Each degree you lower the thermostat on your heating system decreases your fuel bill by 3 percent. Going from 72 degrees down to 68 degrees doesn't matter much in terms of comfort, but it can save up to 12 percent on your heating bill. (All temperatures in this article are in degrees Fahrenheit.)
If you're using a coil-type thermostat, you'll get more accurate readings if you clean it. Pop off the thermostat cover and blow or gently swipe away the dust.
Click to expand...
Five Star, Thanks for the post. I was thinking along these lines when my wife brought me a Martini and there went my whole train of thought.:whistling I think the prof typed it for him to.
 
#10 ·
Five Star said:
I think he had the professor type it into his laptop ;)


You only save 10-12 percent so on a $500 average bill your saving $50 ! if the savings was say 20 - 40% more, id turn my thermastat to 50 degrees to keep the pipes warm and talk to you guys in my ski suite
Click to expand...
You just came to the same conclusion I did and proved my point ...:thumbsup: So if you have an older unit which is not so efficient and you save 3% which give you a total of 12% per unit, 2 zone = 24 % on the average $500 tab you will save $120 and if you have a newer unit and you can save 5% which will give you a saving of 40%...There for if I was you, I put some wool Pj's on and a sleeping cap and start running to your thermostat and lower the F heat :laughing::laughing::laughing::thumbup:
 
#11 ·
Five Star said:
Each degree you lower the thermostat on your heating system decreases your fuel bill by 3 percent. Going from 72 degrees down to 68 degrees doesn't matter much in terms of comfort, but it can save up to 12 percent on your heating bill. (All temperatures in this article are in degrees Fahrenheit.)
If you're using a coil-type thermostat, you'll get more accurate readings if you clean it. Pop off the thermostat cover and blow or gently swipe away the dust.
Click to expand...
What more can I say, other then Heat your home the smart way :thumbsup::clap::laughing::laughing:
 

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#13 ·
Five Star said:
Greg, i see your piont, But the question is not going from 68 to 74!!

I just think that if a one zone first floor lets say, reaches a temp 68 or 72 once the temp is reached, the system cycles when the house looses a degree the system runs to get back to its setting!! ts gonna run regardless as the temp out side drops, so if they keep the temp @ 72 and its in the 20s out its not using more flame or gas as if its trying to hold the house at 68!!
Click to expand...
No, it will run longer to maintain the house at 70°F, then to maintain it at 68°F.

Heat loss through and walls and windows is linear to the temp difference.

At 30° out door temp, and 70 ° indoor temp(40° difference), the house may be losing 61,538 BTUs an hour.
But at 68° indoor temp and 30° outdoor temp(38° difference), its only losing 58,461 BTUs an hour.

Thats a 5% difference on heat loss through just the windows and walls, and on a 4,000 sq ft house, that can add up to a large savings.
 
#15 ·
the colder it is out side or the warmer is in inside, the faster the heat energy is lost to the outside through the walls. its all about the temp difference. if its 68 inside an 68 outside then there is no diff and the unit would not cycle on. the higher the temp is inside or the lower the temp is outside side will affect the temp diff and allow the unit to run longer and therefore drive up the fuel bill. it not all about the air temp. its about humidity and how much total BTU's the air is holding and losing to the outside.
 
#16 ·
If the question is, weather one should leave the stat alone at 68 or 72, or use the setback, my answer is use the setback. As for gas consumption, it's all relatively equal, however, it is better that the motors run steadily as opposed to cycling on and off several times an hour.

Been There and Nick are real sharp guys, I am not disputing what they are saying, as they have forgotten more things than I know. It's just I don't think they are taking into consideration the cycling of the motors.... in regards to the way I am reading the original question
 
#17 ·
thats an interesting point. however, the question was limited to the fuel consumption and cost of operation. we can factor in a countless number of factors and influences for a limitless amount of conclusions. I limited the response to simply the difference in fuel vs. temp set point
 
Discussion starter · #18 · (Edited)
Nick there are alot of variables we didnt consider, But you answered my question, Although from my personal house and as im already paying the bill i just feel that an extra 5% to be comfortable is not alot of difference,

Ive been leaving my thermastat on 72 for the 3rd winter in a row day and night and my Pse&g bill equal pay comes out to $425 for 6 months, last 2 years we were credited due to mild winters and the bill for the summer was around $370 for 6 ,months!! this year ill probably have to pay a difference or it will just increase for the summer!! Its consistant this way versus paying $800-900 winter monthly bills i hear from some people!!

And Next time i go to My Brothers house i will bring longJons for the kids with gloves BRRRR!!!!

Anyway Thanks to all the guys that responded Especially the HVAC :thumbsup:

Nathan
 
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#19 ·
flashheatingand said:
If the question is, weather one should leave the stat alone at 68 or 72, or use the setback, my answer is use the setback. As for gas consumption, it's all relatively equal, however, it is better that the motors run steadily as opposed to cycling on and off several times an hour.

Been There and Nick are real sharp guys, I am not disputing what they are saying, as they have forgotten more things than I know. It's just I don't think they are taking into consideration the cycling of the motors.... in regards to the way I am reading the original question
Click to expand...
He question is on maintaining 1 temp. He was saying it shouldn't cost anymore to maintain 70, then it does 68(thats the way I read it).
 
Discussion starter · #20 ·
beenthere said:
He question is on maintaining 1 temp. He was saying it shouldn't cost anymore to maintain 70, then it does 68(thats the way I read it).
Click to expand...

That is right, this is my original question!! which i still think it cost the same to maintain 68 as it does 72, once the first floor temp is reached maintaining a 1-2 degree differential should be equal!!

except where there is an abundance of windows or vaulted ceilings!!

but as my question went in a different direction i just gave in and followed along!! Thanks Again Guys :thumbsup:
 
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