badgas
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Yowsa thats some juice, how many panels and which inverters are you looking at?
35 panasonic 400W panels EVPV400H and Enphase IQ8M 72-2 inverters
Yowsa thats some juice, how many panels and which inverters are you looking at?
I can tell you first hand with all the air conditioner techs up in the attic it is a lot cooler. It stays about the same temperature as outside. The techs loved it.Look up Fourier's Law. It is the calculations for heat transfer through a wall. One of the LARGEST integers in the formula is the Delta T value. The difference between the 2 different sides of the wall. This is ambient temp, AKA air temp. It is common on 100+ degree days for a standard attic to get up to 140+ degrees (I know, I used to have to work in them). If you have a interior space of 76, that gives you a multiplier of 64 degrees. Now, if you can install an attic fan in a properly ventilated attic and reduce that attic temperature down to 110 - 120, your multiplier has now dropped 20 to 30 degrees. That is a MASSIVE load difference.
All those scenarios for air leakage into the attic do not take into account insulation laying on top of those cracks and leaks. Will air still pass through, absolutely! But being it is impeded and there are other paths that are MUCH freer flowing, the air coming through those cracks will be miniscule at best.
Yes, thermal dynamics, ala convection, is a great way to naturally ventilate an attic. Assuming the ventilation openings and outlets are all in the correct locations and un-impeded. Adding a miniscule amp draw (usually less than that of an incandescent light bulb) electric motor to assist in the process can help a poorly designed attic work better.
Also, heat moves from high to low. Hot AIR rises. Heat doesn't have a direction besides high to low. Materials' thermal conductivity has more impedance to heat transferring into a structure than any sort of convection out of the interior of the space.
If the HVAC system is pressurizing the attic space, then you have FAR larger fish to fry than concerning yourself over the tiny amp draw of an attic fan.
What HVAC guy doesn't say windows play a huge role? They play a MASSIVE role. Specially depending on their orientation (North, West, East, South). I could do heat load calcs to illustrate, but just don't quite have the time ATM.
My parents replaced all their old single pan double hung original 1970's wood frame windows with new double pane vinyl windows and had a LARGE electricity reduction (I cant remember what it was they told me). The house is A LOT more comfortable inside as well.
KWH or KW of output ? 18,000 kwH can be roughly achieved with 3,000 KW output (Average) in 6 hours. Is the "H" intentionally included or is it to be ignored in this case ?Yowsa thats some juice, how many panels and which inverters are you looking at?
KWH or KW of output ? 18,000 kwH can be roughly achieved with 3,000 KW output (Average) in 6 hours. Is the "H" intentionally included or is it to be ignored in this case ?
From this old house
One reason that attic fans are inefficient is that they rely on the existing attic vents (at the soffits, ridge, or gables) to make up the air they exhaust. Usually, these attic vents are not designed for this purpose, and they may not be able to supply enough replacement air. That can put the attic at a lower pressure than the upper floor of the house, which sucks conditioned air into the attic through holes for recessed lights, attic stairs, whole-house fans, and the like.
Conditioned air can also be sucked directly out of unsealed ducts in the attic. In this situation, adding attic fans can cost you more cooling dollars than not having a fan.
H
Don’t Let Your Attic Suck - Power Attic Ventilators Are a Bad Idea - Energy Vanguard
Trade shows can be both educational and infuriating, and there’s one product I see at a lot of trade shows that fits easily into the latter category – power attic ventilators. The variety of this device that’s been popular lately…www.energyvanguard.com
Certainly, KW and KWH being two different units of measure. KW being a measure of power consumed or produced, KWH a measure of how much is consumed or produced in one hour, or hours if plural. A substantial difference as is a 1 KW or KWH vs 1,000 KW or KWH.Its one thing to have 3KW, something total different to have 3000KW - people often misquote and add the h or leave it out
Badgas is going to have 14KW of total panel production on its face -pretty substantive.
How many KWh he gets is up to his roof and shading and location.
CorrectIts one thing to have 3KW, something total different to have 3000KW - people often misquote and add the h or leave it out
Badgas is going to have 14KW of total panel production on its face -pretty substantive.
How many KWh he gets is up to his roof and shading and location.
Correct
They claim/estiamte with my roof that the 14KW system will generate 19,395kWh. This is an estimate and they also say they under estimate by 8% to be on the safe side.
Who knows ? it could be sales BS but I will be pissed if I go down this rabbit hole and the thing produces way under what they estimated.
My River mobile it made a 20 degree difference. But the old were majority louvered. I switched to dual pane low E and put the silver sun block in all the ones with direct sunlight.How much to windows play into home cooling ?
Window companies say it's a big deal HVAC companies say windows do very little.
Any real word examples of how much good windows help ?
I'm in So Cal never ever run the heater but the AC runds from July-Sept.
Over the weekend I ordered a high volume window fan. I’m 5 miles from the beach so I should be able to cool off my second story every evening when the outside temp drops and then run it in the morning right before the sun comes up. Curious to see how effective it is.
Yowsa thats some juice, how many panels and which inverters are you looking
Also from This Old House.
In warm weather, the surface of your roof can get as hot as 160°, heating up the attic space and making rooms directly below the attic uncomfortably warm. This puts a big load on your air conditioning system, causing spikes in your electric bill. One way to minimize this problem is to install an attic fan. This active ventilation system is inexpensive and easy to install. An attic fan will turn on automatically when the attic reaches a preset temperature. The fan is typically mounted behind a gable-end vent, but other types are available that exhaust hot air through a roof vent.
All About Attics
Attics are the space between the roof and the ceiling of the highest floor of the house. They’re usually full of insulation, and sometimes heating or air conditioning equipment as well.www.thisoldhouse.com
Seems to me the message here isnt to avoid them, but make sure if you put one in that you're sure it has enough flow.
Also from This Old House.
In warm weather, the surface of your roof can get as hot as 160°, heating up the attic space and making rooms directly below the attic uncomfortably warm. This puts a big load on your air conditioning system, causing spikes in your electric bill. One way to minimize this problem is to install an attic fan. This active ventilation system is inexpensive and easy to install. An attic fan will turn on automatically when the attic reaches a preset temperature. The fan is typically mounted behind a gable-end vent, but other types are available that exhaust hot air through a roof vent.
All About Attics
Attics are the space between the roof and the ceiling of the highest floor of the house. They’re usually full of insulation, and sometimes heating or air conditioning equipment as well.www.thisoldhouse.com
Seems to me the message here isnt to avoid them, but make sure if you put one in that you're sure it has enough flow.
I will listen to this guy. He is one of the top building science and energy efficiency experts in the US. Pay attention to about the 2:00 minute mark. Listen to what he says about power attic vents. We are talking attic fans and not whole house fans.
This video goes over the proper way to vent an attic. Listen to what he says about radon, pesticides and mold. If think you are smarter than Joe call him up and tell him he is wrong.
What is you cool new roof
I did not watch the entire video but I did run upstairs and count canned lights when he talked about holes in the ceiling.I will listen to this guy. He is one of the top building science and energy efficiency experts in the US. Pay attention to about the 2:00 minute mark. Listen to what he says about power attic vents. We are talking attic fans and not whole house fans.
This video goes over the proper way to vent an attic. Listen to what he says about radon, pesticides and mold. If think you are smarter than Joe call him up and tell him he is wrong.
So you're saying attic fans work nowI will listen to this guy. He is one of the top building science and energy efficiency experts in the US. Pay attention to about the 2:00 minute mark. Listen to what he says about power attic vents. We are talking attic fans and not whole house fans.
This video goes over the proper way to vent an attic. Listen to what he says about radon, pesticides and mold. If think you are smarter than Joe call him up and tell him he is wrong.
How old is that video? The information he is using regarding the A/C is not near accurate for today's standards. Again, this is all with the assumption that there is not enough make-up air coming into the attic.I will listen to this guy. He is one of the top building science and energy efficiency experts in the US. Pay attention to about the 2:00 minute mark. Listen to what he says about power attic vents. We are talking attic fans and not whole house fans.
This video goes over the proper way to vent an attic. Listen to what he says about radon, pesticides and mold. If think you are smarter than Joe call him up and tell him he is wrong.
Phone number?I will listen to this guy. He is one of the top building science and energy efficiency experts in the US. Pay attention to about the 2:00 minute mark. Listen to what he says about power attic vents. We are talking attic fans and not whole house fans.
This video goes over the proper way to vent an attic. Listen to what he says about radon, pesticides and mold. If think you are smarter than Joe call him up and tell him he is wrong.
Its on his web site. Buildingscience.com. and the L is silent.Phone number?
It has nothing to do with the makeup air. Air moves or leaks because of a pressure differential. To suck air in you have to create a differential. The air will come through any opening if there is a differential. Yes more air will come in from vents.How old is that video? The information he is using regarding the A/C is not near accurate for today's standards. Again, this is all with the assumption that there is not enough make-up air coming into the attic.
And BTW, I'd the convection is working correctly, even that process puts the attic into a slightly negative pressure situation or else it won't draw air into the eve vents.
So, like I have said from the beginning, with proper and sufficient make-up air vents in the attic mechanical ventilation can be extremely effective and can reduce the heat load on the interior envelope.
He clearly said attic fans were bad. I have never said they wont reduce temp. I have said they will likely increase your utility bill and are not the solutionSo you're saying attic fans work now
They absolutely do affect your bill, they reduce it, especially the solar fans. He's wrong, as long as your attic is set up properly they work amazingly, you should put one in, you would be shockedHe clearly said attic fans were bad. I have never said they wont reduce temp. I have said they will likely increase your utility bill and are not the solution
Oh please continue to attempt to lecture me in airflow. This is classic! Please tell me again how airflow works.It has nothing to do with the makeup air. Air moves or leaks because of a pressure differential. To suck air in you have to create a differential. The air will come through any opening if there is a differential. Yes more air will come in from vents.
Also i never said it will not lower the attic temp. The more you want to lower it the more negative pressure you must create. Which in turn means a bigger fan and more energy. It also means more air leakage from inside.
You will never see an attic fan in an energy eiificient house because its not needed. The insulation is to keep the heat out.
Air leakage is a super big penalty. To illustrate there is a product called areo barrier that helps air seals homes. A builder in phoenix wanted to sell net zero homes. A code home would have needed a $50k solar array. The builder worked hard and could only get to a hers50 score. That would still need a $30k array. With aero barrier they reduced the ach from 1.4 to .6 and can now get by with just 8 panels versus 30. That is how much air leakage means to an already well built home. In the ops case i am sure the home is much leakier and the fan would contribute to more air from the home.
Air leaks can come from places you wouldnt think it can. Radon travels into the house from air coming from underground. How does that happen.
Everyone has talked about attic air temp. No one has said anything about radiant heat. That is what is by far the bigger load.
The op i assume want lower not higher bills and wants better comfort. Address the issues correctly.
Now come on!! Quit using math and logic here!!
Over the weekend I ordered a high volume window fan. I’m 5 miles from the beach so I should be able to cool off my second story every evening when the outside temp drops and then run it in the morning right before the sun comes up. Curious to see how effective it is.
I have used a window fan in our bedroom for 10 years or more. I am on my second fan because I wore the first one out.
It works great to cool the besroom when it is nice outside. For me, I found it is better to have it blow cool air in, rather than try to blow the warm air out.
I put it on High in the evening, then turn ti low when we go to bed.
What are the improvements?There are some cool industry improvements coming soon to the attic fan world. These are great as long as its cooler outside then inside. Most of them run on temperature so they are great fo rthe Cali market not so much the AZ market.
They are going to be smarter and more functional in all climates. The info I got was confidential but they will be public in a bout 6 monthsWha
What are the improvements?
Thanks!
Thanks!They are going to be smarter and more functional in all climates. The info I got was confidential but they will be public in a bout 6 months
I usually turn on the bathroom fansI can tell you first hand with all the air conditioner techs up in the attic it is a lot cooler. It stays about the same temperature as outside. The techs loved it.