I tried one of those diverters a while back. I found it put too much humidity into the house. The trick is to run the electric dryer for a short time with the exhaust directed outside and when most of the moisture was gone switch it to inside.
Needless to say it went over like a turd at a social. The first time my wife ran the dryer with the diverter installed and all the windows fogged up and the place felt like a greenhouse...well, that was the last of it.
I also have a 1955 Frigidaire dryer, a real gem, it has real chrome trim on it, and is 100% Porcelain (http://en.wikipedia.org/wiki/Porcelain
) inside and out. It doesn't vent outside, instead it has a type of condenser that removes the water from the air after it circulates through the clothes and drains it into a pan at the bottom of the dryer. If I ever finish repairing it and quietly slip it into place where the Maytag currently sits the heat loss problem will be solved. I guess it won't work very well in the summer, though, plus it has a nasty habit of spitting wads of damp lint out across the floor every so often...
Just in case anyone thinks some of the stuff I collect is worthless:http://automaticwasher.org/WANTED/WANTED.htm
My dryer is similar in appearance to this washer:
I used to have 2 wringer washers but scrapped them due to lack of space (can't keep everything!!!).