Installed Radiant Barrier, thinking of solar vents now? (live in, floor)

[ufcrules1]

Sounds like you need a whole new ac unit to me because the one you have is underpowered.

[lh_newbie]

FYI: We replaced an 18-year old HVAC, 4-ton air HVAC system with a new 16-SEER 5-ton unit and added attic insulation; our electric bills in the summer were literally cut in half. It's even lower now that we've replaced a bulk of our old single-pane windows, but the new HVAC made a MAJOR difference. The insulation cut our heating bills by 30% as well - so if you think you have an under powered, old HVAC unit, no amount of insulation or balancing is going to lower your bills like replacing the weakest link in the chain.

Brian

[CRAYH]

I have never seen radiant barrier fail as you describe. There are different types of radiant barrier available. I have been instaling it for 4 years in the Rio Grande Valley of TX. 1) did you leave an air space on both sides, 1/4 in is all that is necessary. 2) did you use the double sided permeated version. If you did the above then you problem is not with the radiant barrier. The biggest problem may be with the AC system ducts. Any house older than 5 yrs will have very leaky ducts due to faulty installation or the adhesive dried out on the tape due to the heat in the attic. It is not unsual for one to lose as much as 40% to 50% of your cold air to the attic. Go buy a roll of the AC tape, a tube of silicon caulk, and a small container of DUCT MASTIC. Remove the old tape, apply new tape, cover the tape with a good coat of mastic with 1 inch on each side of the tape. Cover ALL JOINT CONNECTIONS. In the house remove each room vent and caulk around the edge to fill in any gap between the AC boot and the dry wall. If the opening is to large use foam to fill the opening. If the house has any flex connections, take them apart, apply mastic to the fitting, slide the inside of the flex duct over the fitting, apply mastic around the seal the use a plastic tie to insure a tight fit. Pull the insulation over the entire connection and use a 2nd tie to fasten. Make sure the joint connecting the flex duct to the trunk line duct is also sealed with mastic. Make sure that the AC ducts are not squeezed down in size to fit through an opening. Also make sure there are no 90 degree turns in the flex ducts. If there are try to straighten them out to a lessor degree.

[skids929]

You need to find a way to effectively vent out that attic, it's really the most important part of addressing heat transfer. You need to look at this in terms of heat being transferred three ways. Conductive, Convective, and Radiant. You've addressed radiant and some of the other two components. But you need to get the air moving in that attic effectively, with a properly sized venting system that gives you what is known as Push/Pull effect. This means cooler outside (ambient) air gets pulled through the roof while the hot air is evacuating out of the vent at the top of the roof. This is why ridge and continuous soffit vent are so effective. If you can't put that system in look into powered vents that will have the same effect by sizing them correctly and placing them in the right locations.

If you aren't vented out right your chasing your tail. It's a system that needs to work in concert with each component, insulation, venting, radiant.

[labor omnia vincit sxi]

I had a roofing guy come out to check a potential leak and quote on installing vents... he said that because my roof has multi-angles and different levels, a ridge vent might not be the most effective as there's not enough ridge at the horizontals of the highest part (~ 8 ft). The rest is at lower level and angles of slopes that don't really feed to the highest point.

His opinion is to seal off the current small square plastic vents (8 of them) and add 1 powered vent(solar or etc) to force circulation. He also mentioned that I check my insulations in the attic as that would help. And since I've done that since the winter, he'd recommend that I wait and see the results of this summer it there is any changes before deciding to add the vents. I'm good with that.

So to cap it up, I've added 9 bales of cellulose insulation since the winter, it might help a little but maybe I need more... we'll see.
And from all your great feedback, I am looking at my roof in a more 'educated' way, I'm more incline with a continuous soffit with larger passive vents solution simply because of the shape of the roof (different levels and inclines). A properly placed 1 or 2 powered vents might help but then again it might not.

I'll get an HVAC and take a look at the overall system. I too think that it might be underpowered, coupled with incorrectly placed cooling vents.

[smacdallas]

with all the elevation changes and things you have in the attic you may have quite a few of what I call "hot walls". Are there walls inside the home that face the attic and only have batt insulation in them?

if so, get some foil faced foam board (we usually use 3/4") and cover and seal that wall with it (foil side out). that should help those hot rooms if they are sharing a wall with your attic space. Use foil tape to seal the edges and seams too.

it is something we run across and fix all the time.

[loves2read]

that is what we need to do in our old house and in the one we live in now
both have second floor rooms that have attic space along the walls

what can you do to better insulate the ceiling in those types of rooms--
can you put foil-backed foam board on the ceilings of those rooms as well?

[DaveG99]

Originally Posted by skids929

I can't for the life of me understand why they don't use ridge vent and a continuous soffit vent in Texas. Anyone?

They do. I install them quite often.

[dixierambler]

Originally Posted by loves2read

--can you put foil-backed foam board on the ceilings of those rooms as well?

Not a good idea as that would tend to trap moisture in the ceiling insulation, which would lead to mold/mildew problems. Instead, increase the R-value of your ceiling insulation with batts or blown in loose fill. But don't block upward air flow from the cornice vents.

[adixyz]

Originally Posted by DaveG99

They do. I install them quite often.

I am changing my roof and my roofer recommends whirlybirds over passive vents. I already have an attic fan set @ 105 F and in addition he'll add 5 Whirlybirds as well on the rear side of my house. Although I don't have continuous soffit vents, I increased the number of inlet soffit vents last year and added insulation upto 21". He says with whirlybirds I don't need ridge vents.

If aesthetics is not an issue, what is your experience of using whirlybirds? I am thinking these might continuously recycle hot air compared to just having the attic fan which will only start at 105 F and by this time the attic is already hot.

After the whirlybirds are installed, I am thinking of increasing the Attic fan's thermostat to 115 F. For some reason even if the Attic fan dies, I still have the whirlybirds working.