HVAC and/or attic ventilation

[mrvette]

They make duct wrapping just for that purpose....as if the metal pipes were new.....

I"m tempted to just blow in insulation like a madman and call it a day....

:twitch:

 

[DC3]

I also need to know the truith about radiant heat barriers. They look promising, but the roofers say it decreases shingle lifespan. My roof is new, and that is not desirable. They also require ridge vents, but some say they don't work as well as they claim.

I looked into this one time before and got the same answers you did about shingle life. But I found the decreased life is due to installations that prevent the movement of air between the roof and the radiant barrier. I was told to make sure there is a gap for air to enter the space between the roof and the barrier at the lowest point and another gap at the peak point.

I never followed through with this on my house so I can't tell you how it worked but I did something similar to a storage building I have. I didn't install a the radiant barrier on the storage building but I did completely insulate and seal the attic space so as to have a dry dust free somewhat conditioned storage area. I was told I had to leave a gap between the roof and insulation for airflow to avoid shingle problems. I found some plastic trays at the hardware store just for that purpose that stapled to the rafters. I installed continuous ridge and soffit vents and made sure the air flow could get to the space between the roof and insulation. It's been 10 years or so since I built the building and the shingles seem perfectly fine.

Hope this helps.

Forgot to look for the attic ventilation brochure I think I have. Will try again Monday.

DC

Owens Corning "Raft-R -Mates" ring a bell?

Yep, I believe that is what I used.

I found the brochures I was looking for. One on attic ventilation and one on radiant barriers. They came from a now defunct Texas state funded energy conservation program.

Send me a PM with your email and I'll forward them to you (pdf format).

DC

 

[big2bird]

PM sent. I also read 17 pages about attic ventilation on the HVAC forum. It's like following a thread here about ignition. Lot's of hype, guessing, and some BS, and they are mostly craftsmen. I believe the science lacks serious studies.:quote:

 

[kwplot34]

PM sent. I also read 17 pages about attic ventilation on the HVAC forum. It's like following a thread here about ignition. Lot's of hype, guessing, and some BS, and they are mostly craftsmen. I believe the science lacks serious studies.:quote:

Do an in depth study on it, write a Thesis paper on it,and then publish it so the rest of us can fix our attic's and save on our heating and cooling bill.

 

[cascotty]

Take this for what is worth since I don't have a mental picture of your a/c intake. I know you said you replaced the ducts. When our a/c was replaced they did a pressure test on the whole system and found that the intake plenum which is just 1 ft high and 4 ft by 4 ft area below the heater a/c unit, located in the center of the house, was drawing air from the attic down through the space between studs and sheet rock. To fix the plenum they added a bunch of flat tin and caulking to seal it.

Interesting stuff here, I'm of the same mind, dang electricity and gasoline are killers.

 

[big2bird]

Take this for what is worth since I don't have a mental picture of your a/c intake. I know you said you replaced the ducts. When our a/c was replaced they did a pressure test on the whole system and found that the intake plenum which is just 1 ft high and 4 ft by 4 ft area below the heater a/c unit, located in the center of the house, was drawing air from the attic down through the space between studs and sheet rock. To fix the plenum they added a bunch of flat tin and caulking to seal it.

Interesting stuff here, I'm of the same mind, dang electricity and gasoline are killers.

They did a HERS/Smoke test. That became mandatory Aug 1st of this year. Let's just say I "skated" some permits this time. I have checked every seem visually, and thoroughly, and firmly believe I have duct leaks down to 1-2%.
I also added rigid foam insulation per Noonies suggestion, as well as the scuttle. I added one more whirlybird, and am now gearing up to add an insane amount of eave fresh air intakes.
I also plan on expediting retrofitting my last two exterior walls with R-13 this winter. 22 linear feet, and I'm all wrapped up tight. Dial glaze windows next year, after I recover some $$.

 

[mrvette]

Take this for what is worth since I don't have a mental picture of your a/c intake. I know you said you replaced the ducts. When our a/c was replaced they did a pressure test on the whole system and found that the intake plenum which is just 1 ft high and 4 ft by 4 ft area below the heater a/c unit, located in the center of the house, was drawing air from the attic down through the space between studs and sheet rock. To fix the plenum they added a bunch of flat tin and caulking to seal it.

Interesting stuff here, I'm of the same mind, dang electricity and gasoline are killers.

They did a HERS/Smoke test. That became mandatory Aug 1st of this year. Let's just say I "skated" some permits this time. I have checked every seem visually, and thoroughly, and firmly believe I have duct leaks down to 1-2%.
I also added rigid foam insulation per Noonies suggestion, as well as the scuttle. I added one more whirlybird, and am now gearing up to add an insane amount of eave fresh air intakes.
I also plan on expediting retrofitting my last two exterior walls with R-13 this winter. 22 linear feet, and I'm all wrapped up tight. Dial glaze windows next year, after I recover some $$.

You mean DUAL, glazed, or thermal?? I had those old OEM aluminum POS with the shitty counter balance springs in there, and so maybe 4 years ago, I did the nasty and finished replacing the whole mess of them with vinyl plastic single hung, lo E glass nice and thick spacing like 5/8 or so, on sale at HDespot for ~100 bux each....I did the front pix window much earlier and noted the HUGE improvement in the afternoon, sunlight loading, and winter also....house faces directly West....methinks even in LA you going to find the comfort factor is greatly increased as well as saving a decent amount on electric, but that depends on how much wind you get too, we normally have light summer breezes, even this far inland, like yesterday working on that motorhome in the drive, wonderful day, very pleasant, got lotsa shit done....

 

[010752]

You should easily be able to have 100% joint sealing.
Here new install required to to have the good a/c foiltape and then a generous coating of "duct mastic" over the joints, a fibered paintable sealer just for duct work. It works 100%
Available at a a/c wholesale supply house in 1 gal plastic buckets.

Here are a couple picks of retrofitted continuous soffit vents.
One is a continous rolled screen stapled first then covered.

Next is a pvc (vinyl) soffit, available in several widths x 10ft lengths for around 5 bucks each. Also available in aluminum.

Then you can get either alum or vinyl soffit material, that slides into "j" channels mounted on the tail bottoms. Dirt cheap too. Simce you have no soffit covering now, that would be my choice.

All three give you the max vent area. Easiesr to install than individual vents.

No rocket science necessary. The closer the attic is to ambient temp the better. Just have your ductwork insulated enoigh so it doesn' sweat (dewpoint stuff). Your humidity, I'm sure is much lower than ours anyway.
It will make your shingles last substantially longer too.
Remember insulation is a good investment. It never wears out.

Post some pics of your different soffit areas. Might get some good ideas on working with the PITA (when you need to remove it) stucco.

I put these both up about 20 years ago. One has phillips screws, rusted because too close to the ocean.

 

[big2bird]

Noone,
I used the mylar tape and mastic. I just thru out 2% as a guess, as I cannot smoke test one area.:goodevil:
I'll post some pics Weds. I am working the yacht show, and will be too tired today.
I don't think soffits are the answer for me. You'll see what I mean.
My major concern right now is attic temps, and heat gain in the duct work. We like to leave the fan on low 24/7. Prevents thermal layering , and just is more pleasant.:quote:

 

[mrvette]

Noone,
I used the mylar tape and mastic. I just thru out 2% as a guess, as I cannot smoke test one area.:goodevil:
I'll post some pics Weds. I am working the yacht show, and will be too tired today.
I don't think soffits are the answer for me. You'll see what I mean.
My major concern right now is attic temps, and heat gain in the duct work. We like to leave the fan on low 24/7. Prevents thermal layering , and just is more pleasant.:quote:

Thermal layering?? in a 'modern' high ceiling house like new here in Florida, yes...but I have a standard 8' ceiling throughout...

that layering don't seem to be much issue here, gotta be some, anyway, due to slab construction...

:ill:

 

[big2bird]

Noone,
I used the mylar tape and mastic. I just thru out 2% as a guess, as I cannot smoke test one area.:goodevil:
I'll post some pics Weds. I am working the yacht show, and will be too tired today.
I don't think soffits are the answer for me. You'll see what I mean.
My major concern right now is attic temps, and heat gain in the duct work. We like to leave the fan on low 24/7. Prevents thermal layering , and just is more pleasant.:quote:

Thermal layering?? in a 'modern' high ceiling house like new here in Florida, yes...but I have a standard 8' ceiling throughout...

that layering don't seem to be much issue here, gotta be some, anyway, due to slab construction...

:ill:

Well, I read up on this and stopped it. Seems running the fan reintroduces the humidity from the evaporator.

 

[big2bird]

Installed nine of these today on the wood sections:

Tommarow, I want to cut in 10 or so of these in the stucco with a diamond blade:


That should bring me up to 4sq' intake, and 4sq' exhaust.
I might then try a radiant barrier on the south facing slope. $72.00 for 4'x150', with .03 emmisivity. :sweat:

 

[mrvette]

Running the fan sure seems to increase humidity alright....I suspect ours is a tad higher than yours though.....we run a floor pole fan on oscillate in the brm overnight....that way we keep the a/c on ~77f and we are fine...

that vent in first pix looks like what I cut into the room addition this spring...

got 11 of them, need one more

the old house itself has a issue...hate to spend the effort, unsure of results...

 

[010752]

No wonder you don't want to fool with the soffits. They look pretty big. Here most are 2 ft and with the newer hurricane codes, insurance companies like to have them very narrow.

Are those tails on 2 ft centers? If they are 2x4, I hope you are using the styrofoam or cardboard air chutes to keep the insulation from butting the bottom of the sheathing and blocking the air flow. Again the more soffit vents the better, depending on air speed the turbines can move a lot of cfm, besides just the minimum static action.

Keeping the tstat at 75 vs 78 can almost double the cooling costs here.

Another bad habit I see a lot of thrifty people do is to open up the house at night if it gets to a comfortable temp and then close it up the next day again and turn on the air. You will end up using a LOT more juice doing this because the a/c has to recool all the contents in the house all over again including walls furniture, etc. If the average temps in August require a/c most days then leave the house closed up and just adjust the tstat up to 85 if no one is home, preferrably a programmable one, but don't open the windows. With decent insulation, the interior won't heat up very much. Around here we can dump anywhere from 5 to 20 gallons of condensate a day.

Depending on the sustained outside temps, you can also just use the fan only feature of the system (without the a/c). Once in a while, in the winter, even with the windows closed, we do that.

Our power company almost doubled the kw rate this month.

 

[big2bird]

No wonder you don't want to fool with the soffits. They look pretty big. Here most are 2 ft and with the newer hurricane codes, insurance companies like to have them very narrow.Yep

Are those tails on 2 ft centers?Yep If they are 2x4, I hope you are using the styrofoam or cardboard air chutes to keep the insulation from butting the bottom of the sheathing and blocking the air flow. Nope. I just leave the vapor barrier, and pull the fiberglass out the last 6" or so. It has been fine on the existing vents for years.Again the more soffit vents the better, depending on air speed the turbines can move a lot of cfm, besides just the minimum static action.Yep. Gonna double the vent area.

Keeping the tstat at 75 vs 78 can almost double the cooling costs here.

Another bad habit I see a lot of thrifty people do is to open up the house at night if it gets to a comfortable temp and then close it up the next day again and turn on the air. You will end up using a LOT more juice doing this because the a/c has to recool all the contents in the house all over again including walls furniture, etc. If the average temps in August require a/c most days then leave the house closed up and just adjust the tstat up to 85 if no one is home, preferrably a programmable one, but don't open the windows. With decent insulation, the interior won't heat up very much. Around here we can dump anywhere from 5 to 20 gallons of condensate a day.I agree

Depending on the sustained outside temps, you can also just use the fan only feature of the system (without the a/c). Once in a while, in the winter, even with the windows closed, we do that.

Our power company almost doubled the kw rate this month.

Oh crap, that would kill me here. I already pay too much. I'll post the KWH rate later.

 

[big2bird]

I caulked all the recessed lights in the hallway tonight. Lord, I have become obsessed.:crap:

 

[DC3]

I caulked all the recessed lights in the hallway tonight. Lord, I have become obsessed.:crap:

Hey, caulk is cheap, obsess away. Next, pull one of the supply vent grills and check the gap between the supply duct and the sheet rock. I ended up pulling all of my supply vent grills to caulk major gaps. After that, you can tackle the gaps between electrical boxes and the sheet rock. Any penetration of the walls or ceilings are candidates for caulk. One often overlooked one is tub faucets and shower heads.

DC

 

[big2bird]

I caulked all the recessed lights in the hallway tonight. Lord, I have become obsessed.:crap:

Hey, caulk is cheap, obsess away. Next, pull one of the supply vent grills and check the gap between the supply duct and the sheet rock. I ended up pulling all of my supply vent grills to caulk major gaps. After that, you can tackle the gaps between electrical boxes and the sheet rock. Any penetration of the walls or ceilings are candidates for caulk. One often overlooked one is tub faucets and shower heads.I cut in an access door in my bedroom closet for the tub. I also stuffed insulation under the tub. I'll foam the shower head penetration, and foam the shower handle. Thanks.

DC

Did the supply vents last week. I read they act like venturis, and suck attic air inside. I jumped all over that one.
I also did all the obvious penetrations too. I have sealing romex holes thru the top plates on the list.
I also cut in 5 vents in the stucco today, and am doing 7 more tomarrow. I'll then have most every other rafter bay vented. I'll post a picture tomarrow. They are coming out quite well, and are properly flashed.

 

[mrvette]

When I do flashing, all the women RUN, they act that way for you too???

:bonkers::beer:

 

[68L71]

Oh crap, that would kill me here. I already pay too much. I'll post the KWH rate later.

I would have to check the KWH rate but my electric bill at work has gone up at least $100 from $300 something to $480 for the most recent bill and we have had a very cool summer.