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Ever measure the temp of your attic?

2Driver

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LOL today’s entertainment. Using my trusty digital craftsman's temp gauge.

Outside 108
Attic 119
Driveway surface 150
Pool fence 120

Gotta go check the hose water...

OK, hose water is 133, goes down to 90 once running.
 
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Icky

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That reminds me, I need to replace my attic fan
 

DWC

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This winter I am going to put 1 or 2 exhaust fans in my attic at my pad in LA. By doing this, I should rarely need to turn my AC on
I did it a couple years ago. Helped a bit but not nearly as much as i thought. There are dead spots that don’t get much airflow that don’t seem to cool down much. The tile roof and stucco seem to retain a shit ton of heat through the night so it doesn’t cool down much. Best thing i did was to add a quiet cool whole house fan. Helps on cool nights.
 

Get415

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I did it a couple years ago. Helped a bit but not nearly as much as i thought. There are dead spots that don’t get much airflow that don’t seem to cool down much. The tile roof and stucco seem to retain a shit ton of heat through the night so it doesn’t cool down much. Best thing i did was to add a quiet cool whole house fan. Helps on cool nights.
So is that system only efficient when outside is cooler than inside I'm looking ing into it but it seems good except summer when it's still hot at night..?
 

2Driver

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Honestly I thought it would have been hotter with the new medium grey concrete tile roof.

I do have 2 huge vented gable ends, and eave vents, maybe that’s it as there is usually an ever so slight breeze
 

DWC

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So is that system only efficient when outside is cooler than inside I'm looking ing into it but it seems good except summer when it's still hot at night..?
Yeah, any Whole house fans pull the outside air in through open windows and out through the attic. The advantage of quiet cool is that the motor is away from the ceiling due to an insulated duct. I had a huge, old school 36” unit when we lived in Atlanta. It sounded like a helicopter coming in for a landing when you flipped it on. We can barely hear the quiet cool. I installed a solar attic fan to help keep the attic temps down during the day/into early evening. Helps a bit but it can only cool to outside temps.
 

SoCalDave

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Yeah, any Whole house fans pull the outside air in through open windows and out through the attic. The advantage of quiet cool is that the motor is away from the ceiling due to an insulated duct. I had a huge, old school 36” unit when we lived in Atlanta. It sounded like a helicopter coming in for a landing when you flipped it on. We can barely hear the quiet cool. I installed a solar attic fan to help keep the attic temps down during the day/into early evening. Helps a bit but it can only cool to outside temps.
Same here and I use it every night when the temps are down in the 60's. Anything over 70 and the air is on at night.
 

franky

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I put an thermostatically controlled attic fan on the gable vent on the houses I build. It seams like a good idea to pull that 140 degree air out of the attic when the sun goes down.
 

rivergames

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I did it a couple years ago. Helped a bit but not nearly as much as i thought. There are dead spots that don’t get much airflow that don’t seem to cool down much. The tile roof and stucco seem to retain a shit ton of heat through the night so it doesn’t cool down much. Best thing i did was to add a quiet cool whole house fan. Helps on cool nights.
I live by LAX so it's typically low 80's to 70's at dusk. I just want it to get rid of the hot stagnant air. I'll report next summer :)

I put an thermostatically controlled attic fan on the gable vent on the houses I build. It seams like a good idea to pull that 140 degree air out of the attic when the sun goes down.
How is it working out for ya?
 
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Riverbottom

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I have a temp sensor in the attic. Currently 117* outside, and 131* in my attic. Well vented attic with a gable attic fan.
 

DILLIGAF

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LOL today’s entertainment. Using my trusty digital craftsman's temp gauge.

Outside 108
Attic 119
Driveway surface 150
Pool fence 120

Gotta go check the hose water...
dont have an attic to check.
 

C08H18

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attic is +40 over outside air (without Gable fan ON). Love my gable fans. I keep the fan thermostat at 90-100 year around.
 

LargeOrangeFont

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I did it a couple years ago. Helped a bit but not nearly as much as i thought. There are dead spots that don’t get much airflow that don’t seem to cool down much. The tile roof and stucco seem to retain a shit ton of heat through the night so it doesn’t cool down much. Best thing i did was to add a quiet cool whole house fan. Helps on cool nights.
This x1000.
 

cakemoto

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Foil the inside....works great. Make a barrier between roof and foil
 

Kylemenz1

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We run out whole house fan about 24 hrs a day here in Carlsbad. It pushes out the hot air in the attic very well.

The real trick to cool the house in the evening/night is to only open a couple of windows. And if you have multiple bedrooms you are trying to cool only open each window partially. You can get to the max CFM real quick with every window and door open and you won’t feel any air flow. The attic will cool, but you won’t feel the air flow.

With one or two windows open our will pull the drapes to a horizontal position. And if you’ve got a fireplace make sure your flue is closed and the ash cleaned out. Ask me how I know why that needs to be done!!


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Flying_Lavey

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LOL today’s entertainment. Using my trusty digital craftsman's temp gauge.

Outside 108
Attic 119
Driveway surface 150
Pool fence 120

Gotta go check the hose water...

OK, hose water is 133, goes down to 90 once running.
Laser temp gun? If so your attic temp is so low cause you're only reading surface temps, not the air temps.
I have spent many a times in a hot attic. Worst I ever worked in was 140.
When I was doing residential the first thing I'd do before servicing the unit was set my pocket temp probe on top of the furnace and measure the attic air temp. What it read determined how long id stay up there before coming down for a break and water. I think I had a few 140+'s



Also, for real shocking numbers, read the temps at about 3:30 or 4. Thats after all the heat soak has occurred after the peak of the day .

Sent from my SM-G973U using Tapatalk
 
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Jed-O

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Box fan pushing air outside making negative pressure inside. On the opposite side of the house (master bedroom) I open one window about 6"and it does a great job cooling off the entire house. I do this every afternoon/evening when the temperature is within 4* from outside to inside and shut down when the outside temperature starts to climb. Hardly ever run the A/C. Total cost for fan is like 30 bucks.
 

DWC

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We run out whole house fan about 24 hrs a day here in Carlsbad. It pushes out the hot air in the attic very well.

The real trick to cool the house in the evening/night is to only open a couple of windows. And if you have multiple bedrooms you are trying to cool only open each window partially. You can get to the max CFM real quick with every window and door open and you won’t feel any air flow. The attic will cool, but you won’t feel the air flow.

With one or two windows open our will pull the drapes to a horizontal position. And if you’ve got a fireplace make sure your flue is closed and the ash cleaned out. Ask me how I know why that needs to be done!!


Sent from my iPhone using Tapatalk
Lesson one for me was not to use it at the beginning of Spring in Atlanta. Looked like someone threw a yellow flour bomb at the screen.
36” belt drive unit pulls a crap ton of air.
Unfortunately, it’s too hot inland to run all day. If night temps drop to low 70’s i open up one window downstairs and a couple upstairs. Flushes the attic and brings a nice breeze into the house. Nothing better than turning on high on a cool morning.
 

Justfishing

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This winter I am going to put 1 or 2 exhaust fans in my attic at my pad in LA. By doing this, I should rarely need to turn my AC on

Are you serious?

Attic fans are actually worse for keeping the home cool.
 

Flying_Lavey

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Are you serious?

Attic fans are actually worse for keeping the home cool.
I know what study and findings you are referring to. I have read it and found quiet a few holes in their findings. Their theory of the small gaps and holes from the attic to inside being the areas where the fan will pull air from is quiet laughable. At worst, they don't do much, at best it can drop an attic temp 20 degrees pretty easily. A well designed attic vent system can almost reach ambient temps. Have done a few, both passive and active ventilation, back when I did residential A/C.

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squeezer

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Heat transfer happens three ways. Conduction, convection, and radiation.

A roof inside surface temp of 150 degrees is going to radiate to the ceiling surface no matter what the air temperature in the attic is.

An attic fan only addresses one of the modes of heat transfer.
 

buck35

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Run a mister on the roof and be amazed at the difference.
 

SoCalDave

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View attachment 904794
Box fan pushing air outside making negative pressure inside. On the opposite side of the house (master bedroom) I open one window about 6"and it does a great job cooling off the entire house. I do this every afternoon/evening when the temperature is within 4* from outside to inside and shut down when the outside temperature starts to climb. Hardly ever run the A/C. Total cost for fan is like 30 bucks.
Running Springs..lets be fair...😁
 

69 1/2

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We have 8” open cell spray foam insulation on the under side of the roof. Attic is within 5 degrees of the house temp.
 

napanutt

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Inside temp of the Tesla on a 95 degree day was 143 this particular day. 😳
7F863703-E4EC-41F0-ADB1-E445AF56E0F5.jpeg
 

Flying_Lavey

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Heat transfer happens three ways. Conduction, convection, and radiation.

A roof inside surface temp of 150 degrees is going to radiate to the ceiling surface no matter what the air temperature in the attic is.

An attic fan only addresses one of the modes of heat transfer.
It is also the most efficient way to transfer heat in this instance so addressing that makes the largest difference by a fair margin.

Sent from my LM-G710VM using Tapatalk
 

squeezer

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It is also the most efficient way to transfer heat in this instance so addressing that makes the largest difference by a fair margin.

Sent from my LM-G710VM using Tapatalk

I dont think the facts would support this staement... Surface temps are usually way hotter than air temps. If convection was the main driving function that would not be the case.
 

buck35

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I dont think the facts would support this staement... Surface temps are usually way hotter than air temps. If convection was the main driving function that would not be the case.
Does heat not radiate in all directions?
 

Halvecto

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I put an thermostatically controlled attic fan on the gable vent on the houses I build. It seams like a good idea to pull that 140 degree air out of the attic when the sun goes down.
I replaced the motor on my gable attic fan last weekend, just in time for the heat this week. It was about 120°
up there. Bearings went bad on the previous one. I was pleasantly surprised Home Depot carried a motor and I could just replace in same frame and rewire with same thermostat. We have some big, full trees on both sides of the house. I set the attic fan thermostat to 90. It runs on these hot days from about 2:00 till about 9/10:00. Back of the house never gets above 78° and is quick to cool down at night.

I have contemplated the whole house fan as it is very dry here in SCV and nights usually drop below 65. I read pro/con for the old school whole house fan vs the new quiet cool style.
 

Justfishing

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I know what study and findings you are referring to. I have read it and found quiet a few holes in their findings. Their theory of the small gaps and holes from the attic to inside being the areas where the fan will pull air from is quiet laughable. At worst, they don't do much, at best it can drop an attic temp 20 degrees pretty easily. A well designed attic vent system can almost reach ambient temps. Have done a few, both passive and active ventilation, back when I did residential A/C.

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Why is it laughable. Look at a blower door test on a home. Look at the impact of air sealing on a home.

If hot air rises how is it heating the house below? Sucking the air out of the attic takes electricity. Creating a negative pressure in the attic which pull air from any leaks.

A home builder in phoenix was building home the were much better than code. Better air sealing better insulation. To make it net zero would require a $50k pv array. Using aero barrier to tighten the home brought that system closer to $10k. The shows the cost air leaks have in a house.


So unless your house is air thightbetween the house and attic you are sucking air. Where is that make up air coming from

Radiant heat from the roof is the driving force of heat from the top down. Insulation should be an r40 or greater. Good protection from radiant heat and hot air.

Of course you should have adequate attic venting with more vents low than high.
 
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Sherpa

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Installing my sisters complete forced air system in the attic 4th of July weekend in Chico one summer. 115 by 2pm, attic temps 135 on a calibrated fluke meter. I grew up working in the Chico heat. Thought I was gonna die that weekend.

-Sherpa
 

MooreMoney

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I have spray foam too. Attic isn’t hot at all.
It’s night and day difference from my old house that didn’t get spray foam.

We have 8” open cell spray foam insulation on the under side of the roof. Attic is within 5 degrees of the house temp.
 

Flying_Lavey

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I dont think the facts would support this staement... Surface temps are usually way hotter than air temps. If convection was the main driving function that would not be the case.
The surface temp of the roof may be. However the underside is nowhere neat that hot nor is the structure underneath it. The radiant heat is very minimal. Attics get heated primarily through convection of the roof and its structure getting hot then heating the air below. Take different measurements from the different surfaces in an attic and you will see what I mean. If Radiant was the primary heating method of an attic the ceiling joists would be above ambient temps in the attic. They are not.

Why is it laughable. Look at a blower door test on a home. Look at the impact of air sealing on a home.

If hot air rises how is it heating the house below? Sucking the air out of the attic takes electricity. Creating a negative pressure in the attic which pull air from any leaks.

A home builder in phoenix was building home the were much better than code. Better air sealing better insulation. To make it net zero would require a $50k pv array. Using aero barrier to tighten the home brought that system closer to $10k. The shows the cost air leaks have in a house.


So unless your house is air thightbetween the house and attic you are sucking air. Where is that make up air coming from

Radiant heat from the roof is the driving force of heat from the top down. Insulation should be an r40 or greater. Good protection from radiant heat and hot air.

Of course you should have adequate attic venting with more vents low than high.
Its laughable because a gable mounted prop fan cannot produce enough power to pull any significant amount of air through tiny gaps and cracks. your comparison to a furnace or air handler is pretty much apples to oranges as the FAU/AHU is made with a centrifugal fan at MUCH higher HP that is designed to push through resistance. Prop fans cannot move much air if it is restricted in flow. The only way a prop fan is pulling any significant amount of air from inside the house is if its a significant size fan and all over points of entry into an attic are covered. Having plenty of eve vents not covered by insulation allows the system to work wonderfully as air, and any fluid, follows the path of least resistance.

Heat does rise..... when in an open space. Put a barrier between, like a ceiling, and heat flows from the high concentration to a low concentration. Hot to cold. Your example of the homebuilder downsizing the system meaning much is a moot point as there are far too many variables that affect a PV system pricing to make a direct correlation. Also, were the 2 examples both using sprayed in insulation on the roof versus batt/blow in on the ceiling? That makes a large difference for the Aerobarrier as then that barrier in much more critical to seal the ceiling and any gaps. The ceiling insulation helps to seal those gaps (which are usually sealed now-a-days by most quality contractors before insulation installation) and allows for good thermal isolation between the spaces.
 

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Why the fuck would I want to know I live below Hell🤪
 

Justfishing

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I will take my advise from guys with phd's that have a lot of knowledge in builing science.
The surface temp of the roof may be. However the underside is nowhere neat that hot nor is the structure underneath it. The radiant heat is very minimal. Attics get heated primarily through convection of the roof and its structure getting hot then heating the air below. Take different measurements from the different surfaces in an attic and you will see what I mean. If Radiant was the primary heating method of an attic the ceiling joists would be above ambient temps in the attic. They are not.



Its laughable because a gable mounted prop fan cannot produce enough power to pull any significant amount of air through tiny gaps and cracks. your comparison to a furnace or air handler is pretty much apples to oranges as the FAU/AHU is made with a centrifugal fan at MUCH higher HP that is designed to push through resistance. Prop fans cannot move much air if it is restricted in flow. The only way a prop fan is pulling any significant amount of air from inside the house is if its a significant size fan and all over points of entry into an attic are covered. Having plenty of eve vents not covered by insulation allows the system to work wonderfully as air, and any fluid, follows the path of least resistance.

Heat does rise..... when in an open space. Put a barrier between, like a ceiling, and heat flows from the high concentration to a low concentration. Hot to cold. Your example of the homebuilder downsizing the system meaning much is a moot point as there are far too many variables that affect a PV system pricing to make a direct correlation. Also, were the 2 examples both using sprayed in insulation on the roof versus batt/blow in on the ceiling? That makes a large difference for the Aerobarrier as then that barrier in much more critical to seal the ceiling and any gaps. The ceiling insulation helps to seal those gaps (which are usually sealed now-a-days by most quality contractors before insulation installation) and allows for good thermal isolation between the spaces.
The point of aero barrier comments has to do with air leakage in gerenal. The builder was going behond code with good building practices. Yet air leakage was a significant barrier to getting to affordable net zero.

Now take and older leaky house and place negative pressure in the attic and tell me it wont leak air from the house. Air leakage is from small cracks that all add up. If you had a small leak in your boat would you ignore it oh wait thatyou are going to tell me that is different.

I will listen to PHDs that test and study building science.




I have attended seminars given by Joe L who is quoted in the article. I trust him, Allison and others.

To me the more sensible approach is to add more insulation. In cases where the fans have shown benefit is at low insulation levels. R 11


The florida solar energy center had a paper on radiant heat gain. Again at low r values around r10 radiant barriers werealso mildly effective. When the r value was increased to r38 the benefit dropped to a couple percent. In short with adequate levels of insulation you are protected from both hot air and radiant heat.


By the way all objects give off radiant heat. The bigger the temp difference the greater the flow. So a 140° roof will radiate heat down in the same way the sun heats the earth from radiant heat. Last time i looked it is very cold in space.
 
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I've never been up there, not planning to go anytime soon either. I find I keep much less junk when I don't store it up there.
 

69GS

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I have spray foam too. Attic isn’t hot at all.
It’s night and day difference from my old house that didn’t get spray foam.
I did this also, only thing is I wish I would have done the garage area also. Our house is only 2100' livable and the quote for new blown in insulation was 1600 vs foam for 2300, so I did some research and decided on the foam and well worth it.
 

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We run out whole house fan about 24 hrs a day here in Carlsbad. It pushes out the hot air in the attic very well.

The real trick to cool the house in the evening/night is to only open a couple of windows. And if you have multiple bedrooms you are trying to cool only open each window partially. You can get to the max CFM real quick with every window and door open and you won’t feel any air flow. The attic will cool, but you won’t feel the air flow.

With one or two windows open our will pull the drapes to a horizontal position. And if you’ve got a fireplace make sure your flue is closed and the ash cleaned out. Ask me how I know why that needs to be done!!


Sent from my iPhone using Tapatalk
Accidentally ran the whole house fan with the chimney flute open, wife wasn't very happy.
 

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put on a set of bunker gear and go work outside foe awhile.............
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