The Ideal temperture for cooling in the home ?

[cook42]

What will be considered the ideal temp. to have set for cooling comfort in your home ? I stay in oh and I was telling my customers that 74 degrees was the norm. Please correct me if I'm wrong!

Thanks

[teddy bear]

Forget about telling people their ideal temperature.
Some are comfortable with 78^F with 45%RH and ceiling fan air. When the %RH is 65%, you may need <72^F. 70^F 70%RH is never comfortable to most. You will need to discuss temp, %RH, and air movement. Its a can of worms, unless you are ready to control the varibles.

I promote low %RH for comfort and health along with fresh air during occupancy. You will need a properly set-up a/c and whole house dehumidifier to deliver during all of the varible weather conditions. This is the future.
Regards TB

[danglerb]

Depends on you, your activity level, and local humidity. If humidity is fairly high, maybe address that first, or look at a system with a dehumidify mode. Things like ceiling fans can also raise the tolerable temperatures a bit.

Our AC kicks in at 77 and off at 74, humidity is naturally low in our area (SoCal), but we have no ceiling fans. Cleaning house or other busy activity and I turn on fan portion of the AC, but don't change the temp setting.

[bm17601]

I keep my Infinity at 78 degrees, humidity at 48% and it's very comfortable.

[beenthere]

What ever temp they feel comfortable at.

I prefer 72 myself.

[Shophound]

If only folks had a better grasp on the metric of dew point over relative humidity. When dew point levels are < 55 degrees F, the temperature of the air surrounding a person can vary fairly widely and that person still be comfortable. In my own home I maintain the dew point at around 52 degrees at 75 degrees room temperature.

Activity levels also play a role in personal comfort levels. Go to a gym, upon walking in it may feel cold. Hit the weights or the cardio equipment for half an hour and suddenly the gym just can't be cold enough to keep you from sweating.

[BaldLoonie]

68°

[DanW13]

68* is nice for heating, but for cooling 75* with approx. 50% RH is good for me, the house stays fairly constant during the daytime, until the early evening when the AC kicks on a few times.

[badtlc]

81^F @ 40%RH and a ceiling fan is good enough for my house during the days. At night it sets back to 77 degrees because the bedroom ceiling fan is too loud to run on anything but low.

[Kevin O'Neill]

Set it for what feels for them, not what feel goodto you.

[markf57]

I have an IAQ. Wouldn't if be nice if I could set my thermostat for dew point instead of temp?

[beenthere]

I have an IAQ. Wouldn't if be nice if I could set my thermostat for dew point instead of temp?



NO.

At 80DB and 60DP your RH would be 50.5%
At 76DB and 60DP your RH would be 57.6%
At 72DB and 60DP your RH would be 65.9%

[Shophound]

NO.

At 80DB and 60DP your RH would be 50.5%
At 76DB and 60DP your RH would be 57.6%
At 72DB and 60DP your RH would be 65.9%

The ASHRAE guide for buildings in hot and humid climates strongly recommends that building interior dew points in these climates be maintained below 55 degrees F. With that in mind, your chart changes as following:

80db @ 55dp = 42% RH

76db @ 55dp = 48% RH

72db @ 55dp = 55% RH

The 55 degree dew point or less is based on the ASHRAE Human Comfort Range stated in the Handbook of Fundamentals as well as several other publications, such as Humidity Control Design Guide.

The ACCA Manual J default indoor design temp and RH of 75db @50% RH = 55 degrees dew point.

[Alden_Sloe]

68°
You're one of those that set the temperature at 68 in the summer and 78 in the winter aren't ya :p

[beenthere]

The ASHRAE guide for buildings in hot and humid climates strongly recommends that building interior dew points in these climates be maintained below 55 degrees F. With that in mind, your chart changes as following:

80db @ 55dp = 42% RH

76db @ 55dp = 48% RH

72db @ 55dp = 55% RH

The 55 degree dew point or less is based on the ASHRAE Human Comfort Range stated in the Handbook of Fundamentals as well as several other publications, such as Humidity Control Design Guide.

The ACCA Manual J default indoor design temp and RH of 75db @50% RH = 55 degrees dew point.


LOL... I used 60DP to demenstrate the RH extreme, whentemp is not considered.

Until more systems like the Nordyne IQ's come out.
Using DP instead of temp and RH in residential applications, is not practical.


Personally, I like 72DB 48%RH, which is a DP of 51.3.

[jdblack]

I'm with Loonie.

For relazing time. Call me crazy, but I like to have my thermostat at 68 with my ceiling fans on high and me laying in the recliner with my blanket.

I like to be able to feel a big difference when I climb out of a customers attic and walk into my house.

[Shophound]

LOL... I used 60DP to demenstrate the RH extreme, when temp is not considered.

Until more systems like the Nordyne IQ's come out.
Using DP instead of temp and RH in residential applications, is not practical.


Personally, I like 72DB 48%RH, which is a DP of 51.3.

A bit chilly for me, and my wife would likely smash the condensing unit before resorting to a parka! :D

Toward the end of last week we had outdoor dew points over 70 degrees. Daily highs low nineties. I had no problem keeping indoor dew point below 55 with single stage a/c even on the most humid days. Controlling infiltration - a low tech form of humidity control! :D

[Willserve]

I always tell customers that ask me what is the best temp setting that the power company recommends 78 for energy conservation and lower power bills, but I also point out an a/c is a comfort product and should be set for what's comfortable for them. I also tell them what I keep mine set at because you know they're wondering.

[beenthere]

A bit chilly for me, and my wife would likely smash the condensing unit before resorting to a parka! :D



It can feel a bit brisk some days near the end of an on cycle. :D

Might have to increase my blower speed to 300CFM per ton one of these days.

[teddy bear]

The ASHRAE guide for buildings in hot and humid climates strongly recommends that building interior dew points in these climates be maintained below 55 degrees F. With that in mind, your chart changes as following:

80db @ 55dp = 42% RH

76db @ 55dp = 48% RH

72db @ 55dp = 55% RH

The 55 degree dew point or less is based on the ASHRAE Human Comfort Range stated in the Handbook of Fundamentals as well as several other publications, such as Humidity Control Design Guide.

The ACCA Manual J default indoor design temp and RH of 75db @50% RH = 55 degrees dew point.

For the three above conditions dew point is acceptable. I would prefer a 50^F dew point as more comfortable, 80^F @ 50^F d p = 37% RH, especially with a ceiling fan. I have a client with a home in Miami at this condition, his standard temp/%RH settings. Most feel cool in the home. Some who can afford to go back to their home and install the same set-up. First cost is higher, operating cost are very low. The home has fresh air change and whole house ventilating dehumidifiers. Most impressive!
Evaporation of moisture from skin is affected by %RH. The lower the %RH the higher the evaporation rate, cooler the body is. Absorption of moisture into materials is controled by %RH. Growth of biologicals (mold/dust mites) is based on %RH.
Continue the chart:

80db @ 55dp = 42% RH

76db @ 55dp = 48% RH

72db @ 55dp = 55% RH

68db @ 55dp = 65% RH

64db @ 55dp = 74% RH

60db @ 55dp = 85% RH

56db @ 55dp = 98% RH

My point is 50%RH dp is more comfortable and safer. Do the best you can, but be aware of possible improvements. The surface temperature of coolest spot in the structure determines the %RH at that point. An example is the concrete floor covered by the carpet has %rh based on the dew point of the air in the room and the temperature of the concrete. %RH is critical in controlling biological growth at the concretes surface. The role of the infiltrating/ventilating fresh air's dew point determines the wetting or drying effect on the home. One lb. of moisture raises the interior %RH of 1,000 sqft of home 8%RH. A family of four produce 1-2 lbs of moisture per hour. Without an air change rate, people and their activities raise %RH/dew point rapidly. The air change rate of the home, the dew point of the outside air, and the temperature of the home determine the %RH in the space. When the outdoor dew point is <45^F, clearly the home is being dried. The flow rate of fresh air, the internal temperature, and the internal moisture generation determine the %RH. We need an air change every 4-5 hours when we are in our homes. Controlling %RH by eliminating fresh, damp air is not the ideal way of providing comfort in our homes,
This is a excellent discussion and helps us understand the need and the effect (benefit/burden)of fresh air in the home. Thanks
Regards TB

[jerryd_2008]

...

My point is 50%RH dp is more comfortable and safer. Do the best you can, but be aware of possible improvements. ...

My new 4-ton, 2 stage, 18 SEER DFHP with 5-ton coil/TXV and VS furnace seems to short cycle a lot trying for 50% RH (also have HW VP IAQ Tstat). It seems a bit over sized after moving up from a 10 SEER split AC/furnace even on a fairly tight house with good duct/return sizing.

I keep asking the contractor to reduce the stage 2 blower to 1600-1700 CFM from the current 1900. Seems to be dragging his feet. Any reason he should do this?:confused:

Would the airflow reduction from 1900 to 1600, say, help a lot with the RH control?:confused: Hoping longer run times will help with RH.

[Kevin O'Neill]

Would the airflow reduction from 1900 to 1600, say, help a lot with the RH control?:confused: Hoping longer run times will help with RH.

Yes.

[beenthere]

It would help a lot.

[jerryd_2008]

Yes.


It would help a lot.

Thanks, Guys. BT, I know I seem to re-ask this question but the contractor foot dragging and the small reduction in airflow (maybe 240 CFM) made this HVAC non-wannabe nervous. He's supposed to come over tomorrow so I'll tell him to go for the 1670 CFM setting.

[beenthere]

I run my own as low as 280CFM per ton.

My A/C is a 2.5 ton. So, its usually only at 700 CFM.

You should have your contractor become a member here.

[dan sw fl]

What will be considered the ideal temp. to have set for cooling comfort in your home ? I stay in oh and I was telling my customers that 74 degrees was the norm. Please correct me if I'm wrong!

Thanks

68 _ 69 _ 70 _ 71 _ 72 _ 73 _ 74 _ 75 _ 76 _ 77 _ 78 _ 79 _ 80

__________ NORTH ___________
...... __________ MIDWEST _________
..................................... _____ Mid Atlantic ________
.................................................. ....________ South ______

or something very close

... ... ... ... DEPENDS ON YOUR LOCATION, AGE AND WEIGHT.

[teddy bear]

68 _ 69 _ 70 _ 71 _ 72 _ 73 _ 74 _ 75 _ 76 _ 77 _ 78 _ 79 _ 80

__________ NORTH ___________
...... __________ MIDWEST _________
..................................... _____ Mid Atlantic ________
.................................................. ....________ South ______

or something very close

... ... ... ... DEPENDS ON YOUR LOCATION, AGE AND WEIGHT.
Does the %RH make any difference? Regards TB

[fellowlucky]

I'm with Loonie.

For relazing time. Call me crazy, but I like to have my thermostat at 68 with my ceiling fans on high and me laying in the recliner with my blanket.

I like to be able to feel a big difference when I climb out of a customers attic and walk into my house.

I'm right there with you. I work in the heat all day and I love coming home to my meat locker!

[dan sw fl]

Does the %RH make any difference? Regards TB

Sure, somewhat, but one might ASSUME (for a simplistic presentation)
it could be minor,
IF the RH range is limited to 45% to 53%.

[teddy bear]

Sure, somewhat, but one might ASSUME (for a simplistic presentation)
it could be minor,
IF the RH range is limited to 45% to 53%.
That is a good start. Had more comment, like <40% RH at near 80^F with air movement is delightful. Higher temps with low RH reduces the condensation within the exterior walls. Mold/mildew and mites of any kind are dead. Add an filtered, fresh air change every 4-5 hours when the home is occupied. Now you have the perfect healthy, comfortable, and energy effecient home.
REgards TB

[jerryd_2008]

Thanks, Guys. BT, I know I seem to re-ask this question but the contractor foot dragging and the small reduction in airflow (maybe 240 CFM) made this HVAC non-wannabe nervous. He's supposed to come over tomorrow so I'll tell him to go for the 1670 CFM setting.

Just thought I would report on the effects of lowering the blower speed on my 4 ton York 8T Affinity HP. Here are the blower speed numbers:

Old Stage 2: 1900 CFM New Stage 2: 1670 CFM Difference: 230 CFM Less

Old Stage 1: 1235 CFM New Stage 1: 1085 CFM Difference: 150 CFM Less

Can't believe the difference in run time in stage 1! Went from 4-5 minute short cycling to 3-4 times that!:D

For one of the rare occurrences also got the RH down to 50% with or without over cooling. That is until the wife started cooking and it popped up 5% or so and then ran continuously for an hour maybe in stage 1 without over cooling. Outside temp in the high 80's or 90.

Can't believe what a difference in run time and dehumidification a few 100 CFM can accomplish.

Thanks again, Guys, for the advise.

PS: Thought about posting this as a new thread for others to appreciate but put it here.

[hvaclogic]

Just thought I would report on the effects of lowering the blower speed on my 4 ton York 8T Affinity HP. Here are the blower speed numbers:

Old Stage 2: 1900 CFM New Stage 2: 1670 CFM Difference: 230 CFM Less

Old Stage 1: 1235 CFM New Stage 1: 1085 CFM Difference: 150 CFM Less

Can't believe the difference in run time in stage 1! Went from 4-5 minute short cycling to 3-4 times that!:D

For one of the rare occurrences also got the RH down to 50% with or without over cooling. That is until the wife started cooking and it popped up 5% or so and then ran continuously for an hour maybe in stage 1 without over cooling. Outside temp in the high 80's or 90.

Can't believe what a difference in run time and dehumidification a few 100 CFM can accomplish.

Thanks again, Guys, for the advise.

PS: Thought about posting this as a new thread for others to appreciate but put it here.


Hey Jerry, what part of NWA are you in? I'm in Fayetteville.

[jerryd_2008]

Hey Jerry, what part of NWA are you in? I'm in Fayetteville.

Hi, Bob. We have a Fayetteville address but actually live in Tontitown, famous for politics (UGH!!!!) and grape festivals (Ooooo!).

See you're with Ozark Mountain Air. Believe we stopped to see you down by the old airport but ya never got back to us.:( As you can see we got a York after talking to several other brands, including Bryant.

[Carnak]

The ASHRAE guide for buildings in hot and humid climates strongly recommends that building interior dew points in these climates be maintained below 55 degrees F. With that in mind, your chart changes as following:

80db @ 55dp = 42% RH

76db @ 55dp = 48% RH

72db @ 55dp = 55% RH

The 55 degree dew point or less is based on the ASHRAE Human Comfort Range stated in the Handbook of Fundamentals as well as several other publications, such as Humidity Control Design Guide.

The ACCA Manual J default indoor design temp and RH of 75db @50% RH = 55 degrees dew point.

dp is a big part of my vocabulary

something putting out 60+ is a humidifier

somehting supplying less than 55 is a dehumidifer (in cooling of course)

anything in between is marginal in my books

[wika_boy]

what would be ideal in Hawaii, where i'm from

[dan sw fl]

what would be ideal in Hawaii, where i'm from

Livin in a tiki hut ? ! !! !!!