Question on getting all that hot air out of our garage and attic this summer

[Don]

We live in Denver. Our home is about 3,500 Sq Ft with a 3 car garage. We have central air conditioner. It cools the downstairs great. But the upstairs can get quite hot. The garage is on the west side of the home and gets hotter than 40 hells in there during the summer. There is a south facing gable in the garage. Two bedrooms are above that hotter than hell garage. Question 1: Would a power fan mounted in front of that gable suck out the hot air in the garage even though there isn't another gable to bring in the cooler air?

Above the three bedrooms upstairs is an attic that gets hotter than 47 hells. There is a gable on the east side of the house and one on the west side. I'm thinking something with a bit of power up there could suck that hot air out and help cool the upstairs vs what it is doing now and radiating down into the living space. Here's the twist. We also have a whole house fan mounted upstairs of course. But that sucker could substitute for an engine for a small airplane. Works great but forces us to open windows which defeats the purpose of the central air conditioner. If we don't open windows our home starts smelling like soot from the fireplace. I know this is getting long so thanks for making it this far. Question 2: Based on the facts above what is the best way to remove all that hot air out of our attic?

Lastly, my daughter's bedroom is on the west side of the home. Anyone who knows Colorado knows the west side of the home cooks in the afternoon. To make matters in her room worse .... her vent barely puts out any air. It's been like that from day one. So her room gets hot. Question 3: Based on what you know about my daughters room would it help to have someone install an in duct fan to push more air through her vent? Those $39 register fans I see at Home Depot just look worthless but I've never bought one so I really don't know.

Last part I promise. Our home was build in 1984 and the attic has a bunch of blown in insulation. Should that be removed and then replaced with newer and better insulation?

To those who made it this far thanks. I appreciate your patience. To those who give suggestions even more thanks. I've always found this newsgroup to be very helpful when it comes to stuff like this.

Don

[Bob]

Insulate the @#%^@ out of the attic floor. Just add more insulation with no additional vapor barrier. Then ventilate it. Lots of vent area very low in the attic, and lots of vent area very high in the attic. Powered vents might help, but passive venting is better if you can make it work. The gable vent may "short-circuit" the low/high convection air flow, so you may need to block them. Remember - hot air rises, you want to take advantage of this. Try to arrange the vents so the air flows through the whole attic - there should not be "dead" spots. Plant a to-be-large deciduous tree west of the house.

Be aware that this advise comes from Seattle. YMMV.

Bob

[Don]

We have a 22 year old Ash tree out front. It helps. But keep in mind Denver has 300+ days of pure sunshine. That's why I live here. Summers are much hotter than people think. No humidity but hot.

Ok now I expose my ignorance. What the hell is a vapor barrier?

Don

[Richard Thoms]

Can be as simple as a sheet of plastic, but usually it is coated paper on the insulation. The vapor barrier is usually put on the "living space" side of the insulaton.

Hope that helps.

[buffalobill]

thoughts: hot air rises, air is lazy, hvac additional zone your second floor, hvac additional zone your problem areas, integrate ventilation air by powered dampers into the hvac system, use indoor and outdoor sensors to monitor your sanity and both temperature and humidity, remember that you desire fan ventilation only when the outside air is more comfortable than the inside air, don't waste money on noisy fans, nobody is going to put the fans in and out of the windows except you. also, isn't the whole house fan already blowing the unwanted summer heat from the upstairs hall into the attic where it exits the house attic thru vents? knowledge: read all about ventilation and comfort levels at:

[jd]

sounds like you need a couple of power vents in the roof. These are simply fans permanently mounted through the roof, and attached to a thermostat. At a given temp, they turn on, and start sucking the hot air out of the attic/crawl space. They're not that expensive, and if you're comfortable playing with roofing, they're easy to put in (if not, a general contractor should be able to put them in for pretty low bucks). They draw air in through the soffit vents, so convection is helping too....

The whole house fan i s *supposed* to pull air through the house. if you keep the windows closed, it will suck air back through whatever opening there is - usually a chimney - so you may be pulling air back through your furnace or a fireplace or some such, hence the soot smell.

I wouldn't bother with playing wiht the insulation - no matter how well you insulate the attic floor, unless you manage to get the temp down, you'll get heat penetration. Better insulation will help a bit, but you really need to get the attic temps down....

the idea for some shade trees is a good one. It won't lower the general iar temp, but it will help keep your roof from baking, which is whats making your attic so hot. those roofs really soak up heat - I live in New Hampshire, and a few years ago I was doing a roof in January when it was about 20 below zero. On a sunny day, it was warm enough on the roof to work in T shirts (and there was no heat in the building at the time....)

--JD

[Mac Cool]

It sounds to me as if you lack attic ventilation... when the insulation was blown in, it's possible they covered the soffit vents, if you have soffit vents.

A ridge vent will also help.

Light color shingles will help.

The purpose of the roof is to shed water, otherwise it should be as well ventilated as possible while still keeping critters out.

Once you get the attic ventilated the upstairs temperatures should drop. If they do not drop significantly then you may need to contact a HVAC contractor to zone your house.

[trader4]

To efficively cool any space, whether the garage or attic, you need air intak vents and air outlet vents. As Mac suggested, I would check where the air is coming in. It's very common for insulation to be blocking soffit vents. There are plastic baffles that are made that you can staple to the rafters to keep the channel open. I'd also check to see how big the soffit vents are or if they are blocked with paint. You can install new or bigger ones.

For the outlet, I think a continuous ridge vent is the best way to go. Doesn't use any power and provides even ventilation along the roof.

Adding additional insulation may help too. As for the A/C problem, it's possible the system was designed poorly from the start. I've seen lots of systems where there is inadequate ducting to the upstairs far end reaches. An add on blower may help some, but may not solve the problem entirely. Gettting the attic ventilated will help. Also check the returns for upstairs. Sometimes they are undersized and enlarging the grill opening will help. To really solve it may require either installing more ducts or possibly a second ac for the upstairs.

[Don]

hmmm. havac additional zone my second floor. What exactly does that mean? A separate a/c for the second floor? What are powered dampers? Reread my post. We don't use the whole house fan because that forces us to open up windows which sucks in dust and defeats our a/c. I'm not sure what you really said here. Sorry.

[Don]

I'll look into this. Who does this type of work? A roofer?

I can assure you it is from our fireplace which we use in the winter time. This home originally had no central a/c which is not that unusual for Colorado. So the previous owners used the whole house fan a lot. We installed central a/c many years ago so the whole house fan isn't used.

Shade trees are great. But keep in mind this is Denver. Every tree in this city was planted by a person. This is basically high planes desert.

[Don]

The insulation is on the floor of the attic. not the vaulted part.

[Mac Cool]

Don:

Look at the links I posted. The soffits are also 'on the floor' so to speak. It's not uncommon for for the soffits to get covered when insulation is blown in. If air can't get in the attic, then air can't get out of the attic. Think of it this way... you can't exhale if you don't inhale first. Another thing that will happen is the attic will suck conditioned air from your 2nd story through any leaks contributing to the higher 2nd story temperature.

Before installing additional power vents, check the existing ventilation to find out why it is failing, otherwise no amount of venting is going to fix the problem. At some point you are going to have to hire a professional who understands attic ventilation. The info you get here will help prepare you to have an intelligent discussion with that professional but hire the professional.

[Don]

I hear what you're saying. I'm not sure I want to sift through a boat load of blown in insulation looking for soffits. It seems to me (me being ignorant of this stuff) that if a soffit is on the floor that would mean the soffit is on the drywall which I call my ceiling from my bedroom. If that assumption is correct then wouldn't I see the soffit from my bedroom? If your answer is yes then I can assure you we have no soffits on the floor of our attic.

Secondly I'm not saying anything is "failing". I'm saying it gets really hot up there and that i'd like to get that hot air out. This is Colorado. Homes here are built for winter more than they are for summer. Our home is like toast in the winter. But summers continue to get hotter and hotter (I think it is global warming brought on by Greenpeace). I never said the home is failing. I said my garage is hot and so is my attic. Thanks for your suggestions.

[Jim Nugent]

A picture is worth a thousand words:

[Don]

You're right. Now I see where they are. Under the overhang outside. I'll check it out tomorrow when I have some daylight. Many thanks.

[Mark and Gloria Hagwood]

This is an aside, but something you might want to consider. When you install soffit vents and have blown insulation, the insulation might very well block the necessary airspace between the roof deck and double plate. I've seen this frequently, including my own home. The problem is easier to solve than you'd think. In my case, I used an air hose, connected to my compressor, to blow the insulation back from the airspace, but have also seen it done with a leaf blower. In fact, it's not even necessary to remove the vent screen in most instances.

Mark

[Mac Cool]

Don:

You might be able to check from outside but it's much easier to check fron inside because you can see whether the soffits are covered, check during the day and look for light shining through.

I understand the confusion. Here is the link I posted that explained the soffits.

Although Jim's link is more detailed and may explain it better.

"Really hot" is subjective but if your attic and upstairs are 'too hot' then the attic is failing to ventilate. The important thing is don't let some guy talk you into additional roof vents if your soffits are blocked or you don't have soffits. Clearing/installing soffits will help more than additional vents (not saying that you won't need additional vents). Not only will poor ventilation make you very uncomfortable it will increase your energy costs and shorten the lifespan of your roof.

Best of luck.

[Bob]

Unless it seals very well, the shut-off whole house fan is probably a pretty big source of leaks for your A/C'ed air. If you don't use it, you might want to seal it off.

If you add power ventilators to the roof, unless you have lots on inlet vents in your attic, the fans will suck air from your house through the whole house fan, and any other leaky spots that exist. With the kind of heat you are talking, there should be ways to get good convection ventilation without the power. I bet a properly designed coupola would do wonders. Ridge vents are supposed to be pretty good.

Bob

[Goedjn]

here

This is true, but clearing a vent-path from the soffits to the peak in a finished attic means destroying the finish work, and giving up

2 to 4 inches of space, minimum, when you move insulation from between the rafters to below them. If mechanically forcing air through the peak area works half as well, and costs 1/10th as much, it's a good deal.

[Mac Cool]

Goedjn:

I didn't know his attic was finished. I think you are confusing two different posters. There was a different post about venting a finished attic.

Personally if I finished an attic I would finish it so there were no spaces remaining and any small spaces that were remaining I would fill with insulation.

You can't get something from nothing. He still has to have air inlets otherwise the power vents will suck air from the living space unless the living space is completely air tight and what are the odds of that.