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Xringer · 10-05-10, 10:04 AM

Back in 1956, the builder installed a couple of exhaust fans in this house.
Little fans that vent right into the attic. Not to outdoor air..
One was a bathroom fan and the other was above the kitchen.

We were told venting into the attic could cause all kinds of problems,
but after a few years of not seeing any problems, I replaced the bathroom
fan with a new fan-light fixture combo. (It now uses a newer model w/ CFL).

To keep down the cold-air back-flow, I installed a dryer vent (with it's flap) on the end of the vent hose.
It shuts when the fan is off. I added a small weight to the flap, to keep in from lifting up (and wasting heat)
whenever there was positive pressure in the bath room (door shutting etc).

The kitchen fan was another problem. It leaked a lot warm air into the cold attic all winter long.
When the sun hits the roof, the attic peak wall vents (and now the ridge-vent)
exhaust the hot solar air and create a draft, sucking warm kitchen air up into the attic!

All the little leaks in the house add up.
The draft suction was such, that a 8.5x11 sheet of paper would stick to ceiling vent grill and not fall off!!
The loss in BTUs much have been really high before we got the new replacement windows.

So, we started using a magnetic cover to block the vent input during the winter.
But it was inconvenient taking it down when we needed to vent out the area. (Burnt toast etc).

So, I copied the design of a toilet lid, using a coroplas lid on a plastic bucket. (Removed the bottom of the bucket).
Placed the bucket over the round vent fan(in the attic). The lid flips up when the fan is on.
It drops down when not in use. Extra lid weight (the screw) keeps the drafting down.

The hinge is Gorilla tape and needs replacement every few years.

As you can see, the fan doesn't flip the lid open very wide, when all the doors and windows are closed. (It's cold and wet outdoors today).

I guess we have never seen any moisture problems (in 37 years) with venting into the attic,
because of the attic's peak vents (East side & West side) keep the attic air moving.?.

When we come home to a hot house in the summertime,
that little kitchen fan does a pretty good job of removing hot stale air from the main living area.
At the same time, it's forcing really hot air out of the attic..

Cheers,
Rich

PS:
I can add photos if anyone wants to see them.
Edit: I had a professional cameraman come in and take these marvelous pics!

10-05-10, 10:04 AM	#41
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Back in 1956, the builder installed a couple of exhaust fans in this house. Little fans that vent right into the attic. Not to outdoor air.. One was a bathroom fan and the other was above the kitchen. We were told venting into the attic could cause all kinds of problems, but after a few years of not seeing any problems, I replaced the bathroom fan with a new fan-light fixture combo. (It now uses a newer model w/ CFL). To keep down the cold-air back-flow, I installed a dryer vent (with it's flap) on the end of the vent hose. It shuts when the fan is off. I added a small weight to the flap, to keep in from lifting up (and wasting heat) whenever there was positive pressure in the bath room (door shutting etc). The kitchen fan was another problem. It leaked a lot warm air into the cold attic all winter long. When the sun hits the roof, the attic peak wall vents (and now the ridge-vent) exhaust the hot solar air and create a draft, sucking warm kitchen air up into the attic! All the little leaks in the house add up. The draft suction was such, that a 8.5x11 sheet of paper would stick to ceiling vent grill and not fall off!! The loss in BTUs much have been really high before we got the new replacement windows. So, we started using a magnetic cover to block the vent input during the winter. But it was inconvenient taking it down when we needed to vent out the area. (Burnt toast etc). So, I copied the design of a toilet lid, using a coroplas lid on a plastic bucket. (Removed the bottom of the bucket). Placed the bucket over the round vent fan(in the attic). The lid flips up when the fan is on. It drops down when not in use. Extra lid weight (the screw) keeps the drafting down. The hinge is Gorilla tape and needs replacement every few years. As you can see, the fan doesn't flip the lid open very wide, when all the doors and windows are closed. (It's cold and wet outdoors today). I guess we have never seen any moisture problems (in 37 years) with venting into the attic, because of the attic's peak vents (East side & West side) keep the attic air moving.?. When we come home to a hot house in the summertime, that little kitchen fan does a pretty good job of removing hot stale air from the main living area. At the same time, it's forcing really hot air out of the attic.. Cheers, Rich PS: I can add photos if anyone wants to see them. Edit: I had a professional cameraman come in and take these marvelous pics! Last edited by Xringer; 10-05-10 at 11:23 AM..