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Started By
Message
re: Turbines vs Powered Attic Fan
Posted on 6/1/23 at 4:47 pm to Nawlens Gator
Posted on 6/1/23 at 4:47 pm to Nawlens Gator
quote:
Short circuiting is a myth
Seriously, you sure about that?
1
Posted on 6/1/23 at 5:48 pm to Baers Foot
Was just going to say. Not that I don't believe, but what are the credentials to say that.
Posted on 6/1/23 at 6:18 pm to Tigers4Lyfe
quote:
Not that I don't believe, but what are the credentials to say that.
Masters in engineering and understanding why hot air rises.
Short circuiting requires hot air to sink. Never, ever, happens.
This post was edited on 6/1/23 at 7:23 pm
Posted on 6/1/23 at 9:26 pm to Nawlens Gator
This makes the most logical sense to me. It seems like even IF a short circuit happened, that convection would only draw more air up from the soffit vents.
Posted on 6/2/23 at 5:26 am to Nawlens Gator
Several factors at play and it’s really case dependent. If you have both ridge vents and turbines, you need to ensure sufficient soffit ventilation to match. That’s what most here are likely referring to. Especially with the powered turbines, if a low pressure is created in the attic, that air will be coming from somewhere
Posted on 6/3/23 at 3:17 am to RaginCajunz
Don't go with Garcia. My parents are having a nightmare of a time with them. They just replaced the entire roof and have had nothing but problems with Garcia.
Posted on 6/27/23 at 8:35 am to RaginCajunz
I had two 14" turbines added to my main roof pitch yesterday (just ahead of the monsoon) Today will be a good day to see the results.
Yesterday when I got home from work, I ran two quick tests.
(1) I checked my attic temp vs the outside temp. My attic was 9-10 degrees hotter than outside. I was pleased with that so far.
(2) (this was quite the sight I'm sure) I taped a few bamboo skewers to a telescoping campfire fork. I went up with a lighter and set them smoldering so I could watch the smoke.
A- Smoke lower than the turbines rose rapidly.
B- Smoke equal with the turbines split towards the turbines and ridge vent.
C- Air slightly above the turbine holes rose rapidly towards the ridge vent.
So far, with my small smoke test, I saw zero signs of "short circuiting" at least in the slightly overcast and ~90F outside temp scenario.
Yesterday when I got home from work, I ran two quick tests.
(1) I checked my attic temp vs the outside temp. My attic was 9-10 degrees hotter than outside. I was pleased with that so far.
(2) (this was quite the sight I'm sure) I taped a few bamboo skewers to a telescoping campfire fork. I went up with a lighter and set them smoldering so I could watch the smoke.
A- Smoke lower than the turbines rose rapidly.
B- Smoke equal with the turbines split towards the turbines and ridge vent.
C- Air slightly above the turbine holes rose rapidly towards the ridge vent.
So far, with my small smoke test, I saw zero signs of "short circuiting" at least in the slightly overcast and ~90F outside temp scenario.
Posted on 6/27/23 at 9:02 am to RaginCajunz
quote:
RaginCajunz
Absolute legend.
Thanks for posting your research.
Posted on 6/27/23 at 9:57 am to Baers Foot
quote:
Absolute legend.
Thanks for posting your research.
Hope it helps someone. This week will be the true test. I have a new 4ton unit and these 98F+ days follow the same late afternoon cycle. My AC will cycle on and off throughout the day maintaining my 72 set point until 3-4pm. If it cycles off in the mid-afternoon for a 20 minutes or so, it sometimes rises to 73-74 and struggles to get back down until sometime after the sun goes down.
As I picture it, the lack of attic ventilation has caused a tipping point of overwhelming attic heat and it just can't "drain" the heat fast enough through the tiny vent.
I'd equate it to sitting in a car with a sliver of a sunroof opened. I just opened that sunroof up a lot more with my turbines.
Posted on 6/27/23 at 5:16 pm to Nawlens Gator
quote:
Short circuiting requires hot air to sink. Never, ever, happens.
Short-circuiting is a thing in attics, at least with power vents, I don't think it is with turbines. Short-circuiting doesn't eliminate flow from the soffits. The concern is that it may lower the efficiency because the path of least resistance to flow may be in through the ridge vents when the motor kicks on. However, I would also think that since the ridge vents would keep working when the power vents stop due to hitting the stop temperature it would increase the off-cycle time though it may increase the on-time as well. I wonder if it ends up being a wash. It would be an interesting thing to test.
I only have a bachelors in mechanical engineering but I also sold building materials to support my family and help pay for college. They talked about this in some seminars but this was a long time ago.
I do think short-circuiting is overblown, if you are not re-roofing, I wouldn't remove ridge vents. I think if reroofing and going with power vents, maybe then eliminate them for simplicity sake for the roofers.
ETA: Did a little searching online and here is what I have found. Perhaps mixing is more problematic. One thing I didn't think about was weather infiltration. This is a roofing publication, which made me wonder but it seems if they could talk you into mixing stuff they'd make more money.
https://roofingmagazine.com/fact-or-fiction-mixing-exhaust-vent-types-is-problematic/
This post was edited on 6/27/23 at 5:27 pm
Posted on 6/27/23 at 6:30 pm to mdomingue
I know the info the manufacturer provides swears up and down never to mix. They have fake podcast like YouTube videos about it.
That said, I did a bit more smoke testing today at 5:15pm. I used my Thermapen and a few sticks of nag champa incense.
My thermapen (probably needs calibration) said it was 100 in the shade by my back door. 103 in the sun.
Attic temp 115.2. (Seems really good to me!)
I lit up the incense , which makes much more smoke than the bamboo skewers. Same as yesterday in the hot sun. Lots of upward venting everywhere I smoked up. If even with the turbine hole, the smoke gets sucked to the turbine. Anything above goes right up and out the ridge vent.
AC seems to be maintaining my 72 just fine. Not bad for needing insulation at nearly 100 outside.
That said, I did a bit more smoke testing today at 5:15pm. I used my Thermapen and a few sticks of nag champa incense.
My thermapen (probably needs calibration) said it was 100 in the shade by my back door. 103 in the sun.
Attic temp 115.2. (Seems really good to me!)
I lit up the incense , which makes much more smoke than the bamboo skewers. Same as yesterday in the hot sun. Lots of upward venting everywhere I smoked up. If even with the turbine hole, the smoke gets sucked to the turbine. Anything above goes right up and out the ridge vent.
AC seems to be maintaining my 72 just fine. Not bad for needing insulation at nearly 100 outside.
This post was edited on 6/27/23 at 6:34 pm
Posted on 6/27/23 at 6:49 pm to RaginCajunz
Would the pitch and height of the roof have any bearing on the effectiveness of ridge vents? It seems like it would, but that's just my gut feel.
Posted on 6/28/23 at 1:58 pm to RaginCajunz
I had two whirlybirds added this morning, and while I did not do any scientific measurements before and after, the difference is striking. Just going up in my attic, you can feel airflow instead of stagnant air.
Also, my office has the longest run of a flexible duct which always blew warmer. Now the air blowing out feels like cold air-conditioned air. I wish I would have done this a lot sooner.
Also, my office has the longest run of a flexible duct which always blew warmer. Now the air blowing out feels like cold air-conditioned air. I wish I would have done this a lot sooner.
Posted on 6/28/23 at 2:13 pm to Baers Foot
quote:
I had two whirlybirds added this morning, and while I did not do any scientific measurements before and after, the difference is striking. Just going up in my attic, you can feel airflow instead of stagnant air.
Also, my office has the longest run of a flexible duct which always blew warmer. Now the air blowing out feels like cold air-conditioned air. I wish I would have done this a lot sooner.
That's great! My wife swears the whole house "felt cooler and somehow better" all day yesterday. I hadn't mentioned it in the previous posts, but I did also add one of those attic ladder insulating tents. That was $25 well spent.
Last night, after the sun went down, I tossed the thermometer up in the attic (on the landing at attic floor level). And it was 93.8 and 89.6 outside.
Posted on 6/28/23 at 6:11 pm to RaginCajunz
RajinCajunz
The TD Home&Garden research center. Good job sir!
Posted on 6/28/23 at 6:47 pm to RaginCajunz
quote:
My thermapen (probably needs calibration) said it was 100 in the shade by my back door. 103 in the sun. Attic temp 115.2. (Seems really good to me!)
That is a good temp - I have Bluetooth SensorPush thermometer/RH monitor in my attic, was 127 F at that same time yesterday, outside temp similar your (also SensorPush thermometer reading).
We have a similar house plan but I have more contiguous ridge vent length than you (no turbines). Of course shingle color has a role in attic temperature as well, the darker the shingle, the hotter the attic - mine are gray.
In case you are interested. SensorPush - love these things, have about 5 of them placed around the house and outside, plus one in an carport freezer. Don’t need the WiFi Gateway unless you want to monitor from afar.
Posted on 6/28/23 at 6:47 pm to RaginCajunz
quote:
My thermapen (probably needs calibration) said it was 100 in the shade by my back door. 103 in the sun. Attic temp 115.2. (Seems really good to me!)
Delete - double post.
This post was edited on 6/28/23 at 6:49 pm
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