Clothes dryer heat recovery system

[gascort]

Oh, and I question the statement you made about water vapor - in the wintertime, water vapor in the air is scarce, and as a result, evaporation rates from your skin increase, making you feel colder. Adding water vapor to the air decreases rates of evaporation, making you feel warmer. I have a whole house humidifier on my furnace for this purpose, but I also try to line dry inside whenever I can - I just put my clothes (not the wife's) on a folding drying rack and turn on a small box fan next to them. I figure any E used to run the fan remains in the house, as does all the moisture - a good thing.
We also do cloth diapers, and we hang dry them whenever I take them out of the washer.

[gascort]

I also wanted to add, nice accommodation for the dryer being just a little too wide for the space - it probably makes it easier to empty, too, being higher than normal.

[Daox]

That is a great idea gascort. I know some of the newer gas water heaters do this, specifically the on demand ones. I'll have to take a look and see how easy it would be to make some ducting for it.

The moisture idea is interesting. I too have a whole house humidifier on my furnace, but I have turned it all the way down.

I haven't had time to work on this lately. Its been nice out so I've been working on the cars as much as possible. Later this week its supposed to drop back down though. Hopefully I'll get some time to work on it!

[gascort]

The humidity thing has to have a limit where it can make the cold worse... thinking on it more I think you're correct... I'm going to do some research.

[gascort]

I did some looking and Howstuffworks "How Humidifiers Work" explains it the best I think.
I was thinking maybe wind chill factored in humidity, plus another person posted on Metro's thread about him being cold in his apartment having to do with humidity, but I guess I was right before - more humidity = feel warmer due to decreased rates of evap. from skin.
I have my humidifier set at 40% now - probably should set it a bit lower because on really cold days we get condensation on the walls of our noninsulated plaster-walled living room. Something to fix for next year...
So.. Crank that humidifier back up!

[beatr911]

gascorts idea is very similar to a direct vent fireplace. A tube within a tube acts like a heat exchanger boosting the intake air temp as it moves to the dryer and allowing a cooler setting on the dryer saving energy. Some heat needs to remain in the exhaust so condensation will not occur.

Alternatively or in addition, an automotive type intercooler (like used on turbocharging applications) with a fan could be used to draw heat out of the air, there would need to be a path for water to drain.

[NiHaoMike]

Has anyone thought about retrofitting a clothes dryer with a heat pump? I actually have a LG combo washer/dryer that uses a solid state heat pump to extract moisture. It has had a few problems (drain pump broke down, then a hose cracked - probably from handling while replacing the pump) and is a little expensive, but it uses only about 1/2 the energy of a regular dryer, so it has already paid off its higher initial price and repair costs by saving energy. And don't forget the convenience factor of not having to manually move the load from the washer to the dryer.

The LG dryers that used compressors are probably even more efficient, but they have not been available for years due to the upcoming R-22 phaseout. R-410A would not be a practical replacement for that application since the operating pressures (already high at 400-500PSI high side for R-22) would be too high with R-410A. Hopefully they find a HFC or alternative refrigerant that will work in that application or find a way to make the silicon heat pump work more efficiently.

[Daox]

Now that its getting colder out, we are starting to use the dryer more again. I tried to talk the wife into doing an indoor clothes line but she wasn't too keen on it.

So, I thought about things for a bit, then I wondered if I'd ever be able to quantify any gains by doing anything we've talked about. Thats when I did a little searching on ebay and found this:

Compact Propane or Natural Gas Meter SUBMETER 10063P1 - eBay (item 260497674459 end time Oct-28-09 14:05:36 PDT)

Its basically a kill-a-watt for gas usage. This should allow me to monitor usage for the dryer and the effects of any modifications.

I really like gascorts idea of taking my idea further with the intake ducting. So, I think I'll be looking into that.

[fike]

I considered just using an extra-long uninsulated duct that weaves back and forth through a ceiling joist before exiting the house. I probably would use an extra large diameter duct too, so that the added length doesn't increase air resistance too much.

[Daox]

Welcome to the site fike.

If you cool the air too much you'll get condensation. Not that you can't deal with it, but you'll have to make accommodations for it.