They're coming for your Air Conditioners!

[tacticool]

They can have my Freon when they pry it from my cold, cold fingers.

[03Lightningrocks]

[C-dub]

Here ya go wild bill... I'm no chemist but .... I can google foo with the best of them

Freon is actually a brand name for a class of compounds known that contain fluorine, and are gases at room temperature. If the compound also contains the halogens chlorine or bromine, these compounds are known ozone depleters (CFCs, HCFCs, and so on). The fluorine presents no challenge, but the other halogens do. == Free radical chain reactions == For instance, Freon R-12 is CCl2F2. These compounds were commonly used until it was discovered that they can catalytically destroy ozone. Bromine from Halons has a very similar effect. Here is what happens when these man-made molecules are released into the atmosphere: # They mix in the troposphere # They mix into the stratosphere # When exposed to UV light, the C-Cl bond is broken and the free radical Cl. is formed # Cl. reacts with ozone (O3) to form O2 and ClO, another radical. # ClO reacts with O to form O2 and Cl. # Go back to step 4. and the process repeats itself until the Cl is rained out as HCl. It could repeat ozone destruction 10,000 times plus or minus, depending only on other compounds to tie it back up, and UV not to release it again. The net chemical reaction is this: O3 + O --> 2O2 CFC's remain in the atmosphere for something like 50 years, continually destroying ozone. Since they were banned by the Montreal Protocol, they have largely been replaced by similar molecules, but these new ones are less stable. These new molecules are destroyed before they are able to reach the stratosphere, where the protective layer of ozone is found, and do not destroy ozone. Many developing nations continue to use the old dangerous CFC's however. The R12 Freon (for one example of hundreds) refrigerant was phased out due to being a Ozone (O3) destroying / interactive chemical. It was replaced with R134. Since the phasing out of R12, measurements of the Antarctic Ozone layer show that the Ozone is recovering and is therefore cited as a positive change resulting from environmental policy

Read more: http://wiki.answers.com/Q/How_does_Freo ... z1ykFQgXWQ" onclick="window.open(this.href);return false;

I'm having an organic chemistry flashback. STOP!!!

[WildBill]

They can have my Freon when they pry it from my cold, cold fingers.

Good quote from a tacti-cool.

[WildBill]

I have a question that has come up a few times.

I have heard that, in the summer, it is more efficient and economical to keep your house at a temperature slightly above your comfort level rather than to completely turn off the A/C when you aren't home. So when you get home to can turn on the A/C and cool it down faster and more effeciently. True or No? Comments?

[Winchster]

If you are letting the temperature get more than 5 degrees out of your normal comfort zone, then you aren't really saving anything. The amount of time required to move the temp back down is longer, therefore easily offsetting the "savings" of letting it sit. Think of it this way, under x outdoor conditions it takes the unit in your house y minutes to move the temperature 1 degree farenheit. The further you allow the temperature in the house, to get from your comfort zone, the longer it will take to achieve.

[smoothoperator]

If you are letting the temperature get more than 5 degrees out of your normal comfort zone, then you aren't really saving anything. The amount of time required to move the temp back down is longer, therefore easily offsetting the "savings" of letting it sit. Think of it this way, under x outdoor conditions it takes the unit in your house y minutes to move the temperature 1 degree farenheit. The further you allow the temperature in the house, to get from your comfort zone, the longer it will take to achieve.

If you're going out for two hours, I agree to leave it set the same. I think it you're going out of town for two weeks, you're wasting money by cooling the house while it's empty. The question is where does that line get crossed. 4 days? 4 hours?

[Winchster]

If you are letting the temperature get more than 5 degrees out of your normal comfort zone, then you aren't really saving anything. The amount of time required to move the temp back down is longer, therefore easily offsetting the "savings" of letting it sit. Think of it this way, under x outdoor conditions it takes the unit in your house y minutes to move the temperature 1 degree farenheit. The further you allow the temperature in the house, to get from your comfort zone, the longer it will take to achieve.

If you're going out for two hours, I agree to leave it set the same. I think it you're going out of town for two weeks, you're wasting money by cooling the house while it's empty. The question is where does that line get crossed. 4 days? 4 hours?

In general, I'm referring to the 10 hours or so you're gone while at work. If you are going to be gone for extended periods it's my recommendation to use a setpoint of no more than 85 and leave the unit on. That's what we do in the controls business

[03Lightningrocks]

If you are letting the temperature get more than 5 degrees out of your normal comfort zone, then you aren't really saving anything. The amount of time required to move the temp back down is longer, therefore easily offsetting the "savings" of letting it sit. Think of it this way, under x outdoor conditions it takes the unit in your house y minutes to move the temperature 1 degree farenheit. The further you allow the temperature in the house, to get from your comfort zone, the longer it will take to achieve.

If you're going out for two hours, I agree to leave it set the same. I think it you're going out of town for two weeks, you're wasting money by cooling the house while it's empty. The question is where does that line get crossed. 4 days? 4 hours?

In general, I'm referring to the 10 hours or so you're gone while at work. If you are going to be gone for extended periods it's my recommendation to use a setpoint of no more than 85 and leave the unit on. That's what we do in the controls business

What do you mean by leave the unit on?

[Winchster]

If you are letting the temperature get more than 5 degrees out of your normal comfort zone, then you aren't really saving anything. The amount of time required to move the temp back down is longer, therefore easily offsetting the "savings" of letting it sit. Think of it this way, under x outdoor conditions it takes the unit in your house y minutes to move the temperature 1 degree farenheit. The further you allow the temperature in the house, to get from your comfort zone, the longer it will take to achieve.

If you're going out for two hours, I agree to leave it set the same. I think it you're going out of town for two weeks, you're wasting money by cooling the house while it's empty. The question is where does that line get crossed. 4 days? 4 hours?

In general, I'm referring to the 10 hours or so you're gone while at work. If you are going to be gone for extended periods it's my recommendation to use a setpoint of no more than 85 and leave the unit on. That's what we do in the controls business

What do you mean by leave the unit on?

Wild Bill said

I have a question that has come up a few times.

I have heard that, in the summer, it is more efficient and economical to keep your house at a temperature slightly above your comfort level rather than to completely turn off the A/C when you aren't home. So when you get home to can turn on the A/C and cool it down faster and more effeciently. True or No? Comments?

I say "Leave it on" as opposed to turn it completely off. Depending on the type of thermostat being used the settings would be as follows,
Fan: Auto
Heat/Off/Cool switch: Cool ( This being moved to the "Off" position in Wild Bills scenario )
Setpoint at which cooling is desired: no more than 85


ETA:
The flip side of this would be Heat setting in cold weather with the setpoint at no less than 55

[03Lightningrocks]

I wanted to be sure folks did not misunderstand and think you meant to leave the fan set on. This causes humidity to rise drastically in a house. I would agree with your assertion. I set mine to 86 when I am not home and have it programmed for 78 when I get home.

[Winchster]

I wanted to be sure folks did not misunderstand and think you meant to leave the fan set on. This causes humidity to rise drastically in a house. I would agree with your assertion. I set mine to 86 when I am not home and have it programmed for 78 when I get home.

I can think of VERY few reasons to EVER turn the fan on in continuous mode. And most of those reasons don't apply to a house anyway.

No worries on the clarification. I've been an HVAC construction worker my whole life. I've got pretty thick skin.

[RPBrown]

I set mine at 85 during the day when we are gone, at 3:00 (wife gets home at 4) i have it start cooling to 78 and at 10:00 when we go to bed I drop it to 74. Now if we are gone for extended periods (vacation or weeken getaway) I will reprogram for 85.

[sjfcontrol]

I wanted to be sure folks did not misunderstand and think you meant to leave the fan set on. This causes humidity to rise drastically in a house.

What would make that happen?

[03Lightningrocks]

I wanted to be sure folks did not misunderstand and think you meant to leave the fan set on. This causes humidity to rise drastically in a house.

What would make that happen?

Your duct work runs through a very hot unconditioned space. As the cooler air from the conditioned space circulates through the duct work it absorbs heat from the attic. Like a heat exchanger. If each pass of the air through the ducting picks up even 1 degree of heat, the cumulative affect can add up to a significant rise. Think about what happens when you fill a glass full of ice water and set it on the counter. the outside of the glass begins to get moisture on it. The same will happen from the cooler air in the home circulating constantly through the warmer duct running through the attic. Not nearly as dramatic, but enough that the humidity levels in the home will begin to rise. This doesn't happen when the air conditioner is running and circulating refrigerant through the evaporator coil because humidity is being removed at a rate greater than the rise caused by the duct work.

A secondary problem, is that the blower motor is using electricity and that will result in a rise in your electric bill. A blower motor running 24/7 can consume more energy than many folks realize.

Some programable thermostats have a third option for the fan called circulate. This setting brings on the fan long enough to move the air around, but not long enough to create extreme temperature gains or humidity level increases. This is primarily for air cleaning purposes and has a secondary benefit of moving the stagnant air around the house with minimal affect on humidity levels.