Placement of power vents


#1

I have a newer 2000 sqft Doublewide in south central Texas. It has 7 vents on the roof. 3 on the back half, 3 on the front half and 1 on a dormer above the front door. I recently bought 3 solar powered roof vents. Now where would be best to place them? The ridge of the home is about south to north. The back half has most of the sun beating on it. Originally I was thinking to replace 2 vents of the back half and one vent on the front half with these powervents, but now I am thinking instead of replacing the existing vents to add 2 powervents one on each half and use the third on my shed. The picture is not very good, but it shows what i’ve got in mind. Powervents are rated 1000cfm.
I would be greatful for any suggestions

               http://home.satx.rr.com/kfriedrichsen/images/roof.jpg

#2

If there is not an intake source then the power vents will burn out within a year or 2. If there is a cathedral ceiling then pwer vents are not the way to go. There must be intake for ridge vent also. Email me a pci of the house and if there is any intake sources.


#3

Since you stated that it is a double wide I assume it is a modular home.
What GTP said is 100% correct.
Modulars are a little different, they are built to different codes.
Sometimes there are rafter vents in them sometimes there isn’t…
They always seem to have “bubble” skylights and more penetrations than needed.
You need to make sure the soffits are open so that you have an intake.
This is your soffit vents and rafter vents.
You should remove the “pot” vents (square vents) and sheet over them.
Then you can install a ridgevent or power vents.


#4

There is a Soffit all arround the House and is preforated and also has Round vents cut in about every few feet.
From your replys I gather I should replace some of the old Potvents with the Power vents. Kind of like this.

http://home.satx.rr.com/kfriedrichsen/images/roof2.JPG


#5

Kaiser, where in “South Central” Texas are you? I’m in Austin & could look for you.

One thing about your existing vents - if you leave ANY of them in place, then you’ll be short circuiting the heat rising issues & suck more air in from the static (box) vents than through the eaves.

Also, a photo (posted here, not just Emailed to one of us) would let us know what the profile or pitch is If you don’t have much attic space, then there is a good possibility you’re not going to see much benefit from any kind of solar powered units because there isn’t a whole lot of trapped air to worry about.


#6

I am near San Antonio. This is on a Palm Harbor Energie Star home. The roof is a 4/12 pitch and I do have cathedral ceiling. The “attic” is about 3ft at the ridge. It has two ridge beams side by side so a ridgevent is out of the question. As you can see in the second picture there is only about a 6" opening between the front and back half of the roof.

http://home.satx.rr.com/kfriedrichsen/images/house.jpg

http://home.satx.rr.com/kfriedrichsen/images/roofcon.jpg


#7

With that info, hmmm…

There is zero way i can think of other than ridge vent and that will not work to properly ventilate that roof. Im stumped. Best advise, Sell it. Condisation might not form since your in TX but one thing for sure is you void all roofing warranties on that roof since you can not properly ventilate the roof. Poor design if you ask me. Maybe ranch knows how to ventilate something liek that but i dont have those problems where i am at. I will not do manufactured homes for that reason right there. Certiateed shingles are the only ones that will give you a warranty. A power vent will only cover that beam area its over. It can not ventilate the rest of the roofs since it is 1 chamber next to another if you can understand me. Each chamber is not connect to the other making it impossible to ventilate the other areas.


#8

Just as I suspected…
That type of Modular is very difficult to get to breath right.
The rafters (trusses) are probably full of insulation and there probably isn’t enough heel height at the wall line to fit in rafter vents and insulation.
The best way to fix this is a cold roof, but the structure may not be able to take the additional weight.
Since you are in Texas Ice damming isn’t a problem for you but you still need to get rid of the hot moist air in the attic.


#9

I think you misinterped the second picture. From the top you see a ridge beam, than an opening and below that another big beam. The ceiling inside the home is below that second beam. Behind that beam is open space. All my ductwork runs thru the ceiling and on a hot day there is a bunch of hot air coming out before there comes cool air. So by adding powervents I was hoping to drop the temps up there a little. Even if I pull some air in from the remaining vents I should be dropping the temps up there a little. And since the vents are solar powered it doesn’t cost nothing to run.


#10

Well, I don’t know where my post went to so I’ll do it again.

If you want the ridge vent option, then I can suggest the DCI Smart Vent. It’s usually installed for houses without any soffit vents & it’s design requires you to cut a slot all along the deck from header wall to header wall, with shingles removed & then reinstalled.

Here’s a profile view:

For your application, install one on each side of the ridge line about 2 courses BELOW the ridge.

This means remove the ridge cap, then two courses down, set your saw @ 7/16" (assuming you have a 1/2" type deck) & cut your slot from L to R. Install the product, trim the new shingles where appropriate to allow the slot & then shingle back up. Repeat on the other side & then finally the ridge cap.

If you were to return the solar vents, I’d imagine the smart vent products & new shingles would cost less (the GAF solar units, with tax, will usually run you around 175.00 - 185.00 or so). One thing to consider is the difference in color on the new shingles vs. the existing ones. If your roof is ~6 or 7 years old, you’ve got a high probability of fading & / or algae staining on the old shingles & the new ones will probably look too different.

Either way, you DO need to plug all the old holes if you’re using a ridge vent type product & plus only the unused vents if you stick with the solar products.

Slight aside - I install a LOT of the solar units, so don’t think I’m a hater on that product. That you’ve considered 3 of them seems like a good idea to me.

Split the back slope of the roof into 3rd’s & place two accordingly, then the ridge over the front door area in 1/2 & place a vent in the halfway mark.

If you don’t want a solar unit in the “street” or more curb appealing side, you can put the back slope into 1/4’s & on these marks put 3 of them in place.

As for the humidity mentioned above, we do get a fair amount in Central Texas. When folks up North think of Texas usually tumbleweeds & the dry, high desert plains come to mind but believe me, that’s not the case around here. It’s no Florida, but we do get a lot of humidity during the late Spring, summer & early Fall.


#11

I think that smart vent is a good idea, but it also looks like a bunch of work. Since I just had back surgery I think this project will have to wait 'til the roof gets replaced. So I guess for the time being I will just install the solar vents for now. I’ll do it like ranch said 2 evenly spaced on the back and one centered on the front.


#12

Well,if you are going to wait here’s something to consider since your options are limited.You can put a thin layer of foam insolation over the decking and felt,use i by 4 perlins and install a metal roof ,this will solve any ventilation problems on your next roof job,however it will cost more.