Hi,
I live in a 2- story home with 2- zone heating. Bedrooms are on the 2nd floor. During the day we set the 1st floor thermostat to about 66 or 67 degrees. In the evenings the thermostat for the 1st floor is set to 58 degrees as the entire family will be asleep upstairs. (I live in the northeast.)

What would be the ideal, (most efficient) setting for the 1st floor thermostat in the evening? My concern is that perhaps we are using more energy to re-heat the 1st floor in the mornings, so perhaps we should only reduce the setting by 2 or 3 degrees.

Also, during the day we greatly reduce the upstairs setting as the 1st floor is heated and the heat naturally rises to the 2nd floor.

Any thought on the subject will be appreciated. Thanks for looking...

What kind of heat do you have?

Sorry for omitting the obvious. Natural gas is our fuel, supplied by con Edison. 2nd floor has baseboard devices. st floor has radiators. House was built in 1909. We live 25 miles north of New York City.

With natural gas its is OK to set back as much as you want actually. The only thing a set back does is slow up the rate of thermal transference. In other words at a temp of 72 more heat will be lost than at 65. When you go to reheat to 72 you will use more energy BUT your heat cost will be less overall since the zone was lowered for so many hours and in turn it lost less heat during that time.

Set back thermostats are not miracles. It will only save a small % of fuel but in this day all savings count at the bottom line.

Thanks for the speedy reply and great info. I was just floored by the amount of last month's bill, compared to same period last year.

I always suggest to my customers that they do not lower the non-used zones by more than 5 degrees. Hvac1000 is correct in his reasoning of heat transference. Cold objects radiat cold, warm objects radiat warm. By keeping everything within a few degrees of each other, you are not using more fuel to keep them at a constant. However if you try and heat up an object more than 5 degrees, you use twice the energy.

My thinking may be flawed but consider this... By lowering the 1st floor temp, we are not using the heating system for about 8 hours per day. It's hard to imagine that re-heating the 1st floor in the morning will use more energy than we save by keeping the system set in this manner. Of course I may be incorrect with this theory, which is why I'm posting this topic.

To a degree your thinking is correct. My advice is to try different settings and see what in your opinion is a comfortable length of time the system takes getting the first floor to your liking. Get a programmable thermostat where 1 hour before you get home or get up in the morning, it raises the temperature to your comfort range. Going from 5 degrees to 10 degrees below comfort point will change the length of time needed to get the first floor up to temperature. Try it!

That's my plan. I intend to carefully monitor setting and compare the next bill to the previous one. I will post back the results. Thanks for your response and interest.

Quote:

---

Originally Posted by therinnaiguy

I always suggest to my customers that they do not lower the non-used zones by more than 5 degrees. Hvac1000 is correct in his reasoning of heat transference. Cold objects radiat cold, warm objects radiat warm. By keeping everything within a few degrees of each other, you are not using more fuel to keep them at a constant. However if you try and heat up an object more than 5 degrees, you use twice the energy.

---

Cold objects absorb heat. There is no such thing as cold, cold is the absence of heat.

Quote:

---

Originally Posted by NorthernHeat

Cold objects absorb heat. There is no such thing as cold, cold is the absence of heat.

---

Keep it stupid simple, I try not to impress people with too much techno-babble.

Sorry rpopper for my less than 100% politically correct scientific explanation of how heat seeks cold because I have been publicly disciplined in the fact that there is no such thing as cold. Well good lord' there is a big absence of heat out there tonight!

Lol, Just trying to keep information straight for others who may read these posts for years.

Quote:

---

Originally Posted by therinnaiguy

Sorry rpopper for my less than 100% politically correct scientific explanation of how heat seeks cold because I have been publicly disciplined in the fact that there is no such thing as cold. Well good lord' there is a big absence of heat out there tonight!

---

Well, clearly I'm no expert, but... the production of heat requires energy. A simple law of physics. So, where there is no energy we have the absence of heat, i.e. COLD. It's very real and I suspect that it is defined in the dictionary as well as in physics & chemistry text books. To say there is no such thing as HEAT, is simply incorrect!

I guess instead of saying it is cold we should all say we sure are missing some heat today. LOL Then all the old cold jokes go out the window. Johnny Carson would be up set since he always used the how cold is it scenario for the beginning of some of his shows.

Example How cold is it. Answer It is colder than a well diggers A$$. LOL

How cold is it. It is so cold it froze the balls off the Brass Monkey.

Brass Monkey was the British ship term for the brass cannon ball holder on ship deck. The cannon balls were made of iron. When it would get real cold the brass would contract causing the iron cannon balls to fall off and roll around the deck. A very dangerous situation. History lesson 101.

Quote:

---

Originally Posted by hvac1000

I guess instead of saying it is cold we should all say we sure are missing some heat today. LOL Then all the old cold jokes go out the window. Johnny Carson would be up set since he always used the how cold is it scenario for the beginning of some of his shows.

Example How cold is it. Answer It is colder than a well diggers A$$. LOL

How cold is it. It is so cold it froze the balls off the Brass Monkey.

Brass Monkey was the British ship term for the brass cannon ball holder on ship deck. The cannon balls were made out of iron. When it would get real cold the brass would contract causing the iron cannon balls to fall off and roll around the deck. A very dangerous situation. History lesson 101.

---

I've heard that before also, but just about a year ago I heard the brass monkey theory was but a myth, lets ask Myth Busters.

Cold is easier to say than a total lack of heat energy, plus the word cold has been around longer than physicis new what heat energy was, but ancient people new what an absence of heat was "COLD!"

I only said something about it because of the statement "cold radiates cold" which was incorrect, I f you had said cold absorbs heat I would have been fine with it. And now you are trying to compare that with the new statement, because heat is a form of energy there is no such thing as HEAT. So I went back to 2 college physics books and the word cold is not even in the glossary or the index. So then I went to the dictionary and it says
1 "The absence of heat"
2 "the sensation produced by low temperatures"
3 "A mild viral infection involving the nose and resperatory passages (but not the lungs)"

I'm done with this post now.