[makdan]

Whose AC philosophy is more defensible and why? (I have a strong opinion on this, but want to be able to show the other party a response from an objective, disinterested third party.) Do both sides have valid points, or is there clearly only one reasonable position? How unreasonable is the less defensible position?

Situation: 10:15 am on July 8, near Washington, DC, where summer humidity is almost always high and the high temperature for the day is projected to be 98, with wind between 2-5 mph. House is currently at 70 degrees, as measured by thermostat, while outside temp is significantly higher, but still nowhere near 98.

Person A: wants to leave house doors and windows open until indoor temp reaches 75, then close house up and set AC on 71. No underlying rationale stated for this position.

Person B: wants to close house immediately (hours earlier, actually), reducing heat and humidity inflow as much as possible, relying on insulated house to keep house cool for several more hours before AC will be needed. Points out to Person A that warm, humid air can be felt to be flowing in across screen door boundary and that AC's basically do 2 things, remove humidity and reduce temp. And as a result, letting in more heat and humidity will cost more to keep house cool. Also appeals to Person A's sense of environmental concern.

The is by no means an isolated scenario. Help!

[ordinaryguy]

Person B (that's you, I'm guessing) is right. Keep the heat and humidity from getting in in the first place rather than paying to pump it back out later. It's a no-brainer.

[makdan]

Whose AC philosophy is more defensible and why? (I have a strong opinion on this, but want to be able to show the other party a response from an objective, disinterested third party.) Do both sides have valid points, or is there clearly only one reasonable position? How unreasonable is the less defensible position?

Situation: 10:15 am on July 8, near Washington, DC, where summer humidity is almost always high and the high temperature for the day is projected to be 98, with wind between 2-5 mph. House is currently at 70 degrees, as measured by thermostat, while outside temp is significantly higher, but still nowhere near 98.

Person A: wants to leave house doors and windows open until indoor temp reaches 75, then close house up and set AC on 71. No underlying rationale stated for this position.

Person B: wants to close house immediately (hours earlier, actually), reducing heat and humidity inflow as much as possible, relying on insulated house to keep house cool for several more hours before AC will be needed. Points out to Person A that warm, humid air can be felt to be flowing in across screen door boundary and that AC's basically do 2 things, remove humidity and reduce temp. And as a result, letting in more heat and humidity will cost more to keep house cool. Also appeals to Person A's sense of environmental concern.

The is by no means an isolated scenario. Help!

I appreciate the votes of confidence from ordinaryguy and CaptainRich, but forgot to ask that respondents mention their credentials.

Are either of you HVAC experts, or is anyone else out there, who is an expert, willing to answer further perhaps in more detail?

[Dr D]

Ordinaryguy offered a concise answer based on his correct understanding of laws of physics. My guess (and I extend a sincere apology in advance if I am wrong) is that your debate of this topic is with a lady who has never completed an eighth grade science course, and doesn't have a clue. Please tell me that I am wrong, as I have the utmost respect for ladies.

[acetc]

Person "B" is correct, when the house is left open as you have stated ,humidity as well as higher temperatures permeate the home and everything in it. As you have stated the higher humidity(latent heat) is removed along with lowering the temperature. The higher the humidity, the harder the a/c has to work, its not just about four degrees on the stat.
Thirty seven years in the HVAC trade. Mike

[makdan]

Dr D: It is a lady, but she is quite intelligent, has had considerable education, and currently has a straight-A average over halfway through a PhD program in nursing, with considerable emphasis on quantitative methods, statistics, etc.

I strongly suspect that her total rejection of my philosophy stems directly from our deteriorating relationship, but I still cannot understand why she would be so stubbornly resistant to my expressed reasoning, preferring to take instead what I think is a totally indefensible position.

Another example: she vehemently rejected my suggestion on a warm day with a breeze to open upstairs windows to get a cooling breeze from downstairs (where windows and doors were already open), thereby blowing the upstairs hot air to the outside, while also benefiting from the cooling effect of the air flow. Her response: hot air rises, so letting air from downstairs flow upstairs would make it hotter there. I can only shake my head in knowing disbelief.

[Dr D]

Makdan: Since your lady is learned, and should know better, the discussion of heating and cooling is but a foil for her desire to prove you wrong at any cost. I would wager that this disagreement is not the only one that the two of you have had. It may be time to reassess your relationship with this lady, and have the two of you decide whether it is time to part company, or seek professional counseling in an effort to fix a problem that will not get better without attention.

[ordinaryguy]

Dr D: It is a lady, but she is quite intelligent, has had considerable education, and currently has a straight-A average over halfway through a PhD program in nursing, with considerable emphasis on quantitative methods, statistics, etc.

Yeah, but no thermodynamics I'll bet.

I strongly suspect that her total rejection of my philosophy stems directly from our deteriorating relationship, but I still cannot understand why she would be so stubbornly resistant to my expressed reasoning, preferring to take instead what I think is a totally indefensible position.

Now we're getting to the heart of the matter, which of course has nothing to do with latent heat or humidity. She won't believe your explanation of why the sky is blue either, because she thinks you're an insufferable self-important smart alec. Superior intelligence isn't as big an advantage in life as you may have been led to believe. It makes it harder to be humble, which is way more useful than being smart.

forgot to ask that respondents mention their credentials.

BS, Engineering; MS, PhD, Economics; 13 years of cattle ranching; 21 years of marriage.

[hvac1000]

Sounds like a soon to be lonely hearts club in here. LOL