[Greenbuilding] Laundry day on the GB List

[jfstraube]

If you have an airtight house (and you should if you care about the energy in the exhaust stream of a clothes drier) then dumping the moisture into the indoors has a high risk of causing moisture damage.  We and others have definitely have seen this moisture source cause problems.
Exhausting a gas range to the interior is a risk, again, if you have an airtight house.  A drier tends to have a larger burner that runs for long chunks of time on full output.  I do not know the relative CO output of a range vs drier, but I fear for the IAQ if the drier vents indoors.

Does the electric condensing drier save $?  Depends on your relative electric rates.  A Heat Pump condensing drier does use less than 1/3 as much electric energy than does a good gas drier, and so if the energy cost of electric is less than 3 times that of gas (and it usually is around that) then yes.  But there are places where electricity is quite expensive relative to gas (some places in New York State come to mind) and other places (like Portland) where electricity is cheap relative to gas.

I know some of the Miele and Bosch 12 lb capacity driers in Europe and Australia use less than 2 kWh/load.  And a normal gas drier exhaust 200 cfm of air, which is not a trivial energy cost in a good home.
I am pretty sure we will eventually move to heat pump condensing driers but it will take some time to penetrate the US/Canada market.


On 2010-10-23, at 9:58 AM, Benjamin Pratt wrote:

> I believe condensing dryers are electric, while RTs device would allow a gas dryer to exhaust to the indoors. However, I am not sure about the safety of doing so. Obviously a gas furnace or water heater exhausts to the outdoors to prevent carbon monoxide poisoning. A gas range, however, does not.
>    I need a picture of RT's device to understand it. (Can one purchase such a device?)  My idea was to harvest some of the heat from the exhaust duct by making or buying a finned duct and using a fan to cool it. This would only collect a fraction of the escaping heat, but it would not allow carbon monoxide to enter the indoor air--if that is something to worry about.
> 
> Also, I still have the question of whether an electric condensing dryer would save money over a gas conventional dryer. Anyone have an answer?