Insulating around attic fan

[Amanda Robin]

Hi all,

I would like to invest in some insulation for my 1400 square foot house but there's a problem.

My house has a built-in attic fan. For those who don't know, it is used to draw in outside air to cool the house. In my area of the US, mid-south, it isn't practical during the summer because even the nights don't cool off much or dehumidify. It's nice during the fall to get the cool night air in and the heat of the day out.

When it is turned on, metal slats open in a rectangular area in the ceiling to vent the house's air into the attic (you have to open some windows in the house).

I hardly use it. But you can see where it could be an energy saver for certain times of the year.

However, its location in my house is a terrible design. It is in the ceiling of the same hallway that also contains the intake for my central heating/air conditioning. Although its slats are closed when not in use, lots of air leaks through. So in the summer, the HVAC intake sucks the hot air from the attic through the slats and into the AC system. In the winter, it sucks the cold air into the heating system. You can feel the draft in both cases.

The temperature differential through the house also verifies that this actually happens. My den is often up to 78 degrees in the winter as the system struggles to get that cold hallway up to 70 (that's where the thermostat is, too, unfortunately).

A few years back I stopped trying to use the fan and I sealed it off with 6 mil plastic. But there is still an enormous leakage problem, not to mention the conduction of heat through the metal fan and slats assembly.

My questions are:

1) Would there be a way to insulate the slat area with some kind of material cut to size and laid on there? I would have to be able to slip it by the fan. I can provide dimensions and/or photos if anyone has some ideas about thisl.

2) If #1 isn't possible, is there any point to taking other steps to insulate? It seems silly, for example, to increase my attic insulation in other areas while leaving this gaping leak. Ditto insulating around windows and doors. But maybe it's not?

3) I've been thinking about getting an attic ventilator in the roof to decrease temperatures in the summer. Do you think it would have a measurable positive effect, even considering the leakage through the fan slats?

4) What if I get the fan professionally removed? Worth it?

Thanks for any tips. I would really like to insulate around it if it would be possible and effective.

Amanda

[barry]

I'd:

1) Remove the monster fan, close & insulate its hole. 2) Install thermostatically controlled attic exhaust fan, ensuring adequate air inlet area; this will cool attic and reduce shingle-roasting. Reduces heat-load below, of course. J

[tev9999]

I've got the same concern now that I had AC installed last summer. My plan, which I have not implemented yet, is to build a thin insulating panel - probably some paneling (white to match the ceiling) with some weather stripping that I can attach to the ceiling in the hall to cover the fan and stop the air leaks.

Also had a recommendation years ago to build an insulated "box" to go over the fan in the attic. Rig a pully to be able to lift the box off of the fan from the attic access since it is a pain to crawl over to it. I'll probably just throw some rigid foam insulation over it and forget about it. I have a feeling I won't be using it much next summer, but don't want to bother having it removed right now.

[CJT]

I use an attic exhaust fan and I think it helps, but it's not a slam-dunk when it comes to energy savings, because they use a surprisingly large amount of electricity (partly because they run a long time, at least here in Texas, for any reasonable setting of the thermostat).

[mm]

You mean a powered ventilator, right? What I calll a roof fan (or a gable fan.)

Absolutely. I only live in Batlimore, where it is probably cooler than the mid south, whatever that means (in the mountains, the piedmont, the savannah?) but since I put in my roof fan it took probably 40 degrees off the temperature of the attic and 10 degrees off the temperature of the floor beneath the attic. (the second floor in my case.)

I don't like to use AC. It costs a lot of money and I have to close the windows. The first summer, when I got home from work, it was so hot, I couldn't bear to go upstairs. I ate in the kitchen, slept in the basement, and went upstairs the next morning to bathe and get new clothes.

After the fan went in, instead of being 95 upstairs, it was 85 and got cooler as the evening went on. When the attic was 140 in the day time, it took all night until the 2nd floor was tolerable.

If you do use AC, it will save a lot of money. If you still have a leak by the whole house fan, I think that is separate, and unrelated.

It uses a thermostat to turn itself on and off. Starts at about 10 in the morning on a sunny summer day, and ends about 9 at night. So it makes no noise when I'm trying to sleep.

I also installed the two suggested switches, one to turn it on when it wants to be off, and one to turn it off when it wants to be on. I use the second in the fall and spring, to let the attic get warm in the day, so it heats my house in the evening and night. I"ve never used the first switch because it is meant for people who take steamy baths and showers, and need to exhaust humidity from the attic. I don't make much steam. But it took almost no effort to put it in so I did that. I used a double toggle switch that fits in a single gang box, and it's in the hall directly below the fan for that matter, but mostly in the hall convenient to my bedroom.

I do have to change the motor, 3 or 4 times in the last 22 years, but I change it from inside the attic, and I've gotten the time down to about 20 minutes. Turn off the breaker, remove 2 wires 3 screws and a set screw to remove the fan blade. Reverse.

I bought my first replacment motor from the fan company, but since then I just go to Electric Motor Repair, in Baltimore, which has all kinds of motors in stock.

Originally, I bought the most expensive fan they had for sale, hoping to decrease mainenance, bu tthere was only about a 10 dollar difference in price anyhow. Maybe with inflation that would be a 20 dollar difference. I was up on the roof last summer, after 22 years, and the fan looked as good as new, but I didn't touch the plastic. I know better than to look for trouble. (I don't know how long the plastic will last, but since the fan can't be seen from the ground, I would make my own replacement if it ever cracks and blows off. Again, it can be measured from the inside of the attic. If they coudl see the fan, I'd just make the cover pretty.)

Some motors last a long time, one as little as 3 years, I don't know why. But I don't care, because the fan is great.

Remove NOPSAM to email me. Please let me know if you have posted also.

[mm]

Oh yeah, make sure you have adequate air intake directly into the attic from the outside, and not from your air conditioned house. That usually means soffitt vents.

I have a townhouse with continuous soffitt vents from one side to the other, in front and in back. I'm not sure that much is necessary, but that is the way the house came and I"m not complaining.

Also, after about 15 years, I noticed that part of the screening that cover the soffitt opening was clogged like the lint filter on a dryer, and all of it was covered with some amount of stuff. That shows how much air is going through the vents. I peeled off the stuff like I peel it off the lint from the dryer filter, and I figure I'm good for another 15 or 10 years. There's nothing I can do to prevent this except clean the outside air, including leaf particles, chopped up grass, etc. I'm not talking about soot or winter stuff.

I definitely would not take out the fan, unless I absolutely needed the space. When you sell it many prospective buyers will like it because after 22 years, such fans are still much more respected here than roof fans.

Because the attic never gets that hot, the house never gets that hot, even if I'm out of town with the AC off, and because of that things in the house don't dry out like they would if it were hotter. Of course everything dries out with time, especially plastics and vinyl, and some woods, but it's good that the house never gets that hot.

I don't turn the fan off when I go out of town. The motors have thermal protection, I'm almost positive,, and every time one has failed, it's just stopped spinning, and was hard to turn by hand also. I don't think fire is an issue, afaik.

Remove NOPSAM to email me. Please let me know if you have posted also.

[Bill Gill]

I have the same problem. I like the fan in the spring and fall, but it doesn't help much during the summer and winter. I made a sliding panel to cover the fan when it is not in use.

The panel is made of plywood with a 1" layer of foil backed foam insulation in it. I put some door weather strip on the end to keep air from leaking out from under it. I built a frame up against the ceiling to hold it. In my case it takes up the whole width of the hall. I have an operating handle in the middle of the panel and use a stick to push it back and forth to open and close it.

Of course just recently I saw a thing in the paper that you can buy a sheet of insulation with magnets on it that will stick up against the louvers to help with the problem. The problem I see with that is having to keep climbing up on something to put it in place or to remove it.

Bill Gill

[nielloeb]

Yes. Insulating will help.

That depends on what ventilation you have now. Google is your friend.

You said you like the fan. So keep it. Also, the cost to remove it might be more than the energy savings.

Buy a bag of faced batt fiber glass insulation with a high R value (ask at the store). It will likely be four feet long. Cut it into two,

2-foot lengths. Go in the attic. Stuff it -- paper side down -- onto the top of the fan's slats. When the weather it right for using the fan, remove the insulation until it needs replacing.

[Tony Hwang]

Hi, Ventilator? For air to move, just pushing/pulling air with fan is not enough. Law of physics requires air has to come in and go out. How is your under eaves soffit? With proper insulation on the ceiling heat loss is minimal through the ceiling. Tony

[Heathcliff]

What I do is in the fall, I go up in the attic and spread an old blanket over the slats from above. Then I spread out a sleeping bag or two over the blanket (since we're not winter campers). Low cost and effective. Yes it's a pain reaching through the fan to do this but it can be done.

The way my installation is makes it impractical to just fit a cover over the whole thing, but if I could that's what I would do. If the topside of your fan is such that you can lay a flat sheet of plywood or something over it to seal it off, that would be easier. You could make a cover out of plywood or even cardboard and staple some fiberglass insulation on it. --H

[Bill]

I've had good luck doing the following: I build a plywood (or rigid foam) box around the fan. In the winter months I cover the box with a sheet of rigid foam insulation. I put a piece of 2x4 wood on top (as a weight), else a gust of wind may create enough pressure to move the top cover. I also put a few sheets of newspaper over the fan blades, creating more dead air space. I also make sure there is an extra kill switch in the attic, so no one accidentally turns on the fan. If you can't easily reach the fan from the attic, you could rig up some type of (light weight (use rigid foam)) hinged doors (as the top cover, which could be opened/closed from underneath).

You can also build the same type "box" over pulldown attic stairs and save energy costs.

Amanda Rob