Heat for clothes dryer idea
 

Here is an idea I saw on a sailboat about 15 years ago, and thought it might give someone some ideas.
The boat had a built in clothes fryer drum, that had the hot air coming off the refrigerator, ducted to heat the drum. Not sure, but I assume it was wired so the drum turned, when the refrigeration compressor came on.

I guess I wasn't aware that fridges really put out that much heat... Anyone have any numbers they could run?

I just had an idea from the fridge exhausting thread. You could plumb the fridge exhaust so that it was loosely coupled to the dryer suction inlet. That way, when the dryer operated, it would naturally suck warm air from the fridge. The increased airflow should help the fridge's efficiency, and the heat would be recycled to dry clothes, a double whammy!

The amount of heat rejected from a refrigerator is minimal and doesn't usually run long enough for a full dryer cycle. Dryers also need max CFM air flow and ducting the fridge into the dryer might be a net loss in and of itself. My fridge 150 watts and runs for 10-15 mins at a time. Dryer has an element in it that produces 33x more heat than the refrigerator when it is switched on.

Your gains will be very minimal in theory but if you are ducting your air flow through the dryer outside the small period of fridge operation, you'll likely be doing damage to the refrigerator efficiency. I can't see a worthwhile net gain here and see plenty of flaws in the effort. Might help if this is all timed for the recovery of a defrost cycle though, that's a good 30 minutes of runtime while cooling off a hot freezer coil and using higher compressor amperage.

I'm not saying to reroute ALL the intake air, maybe just run a dryer hose so it covers up a few louvers on the back plate of the dryer near the blower intake. The suction would be a couple mm of water, enough to help the warm air through the hose while both units are running. Similarly, the discharge of the fridge could be coupled loosely enough not to drastically reduce airflow while the dryer isn't running. If it worked in a sailboat, it could work in a house. Total improvement in efficiency would be better than that of your average law firm.

Was it a gas fridge?