[Greenbuilding] dehumidifying bathrooms - makeup air?

[Michael O'Brien]

Hi, Reuben—

A dehumidifier removes heat from water and leaves it in the space. They have a COP of about 1.2 (last I checked), so you could think of it as a supplemental heater.

Best, Mike
Sent from my iPhone

> On Dec 16, 2017, at 9:13 PM, Reuben Deumling <9watts at gmail.com> wrote:
> 
> I'm going to piggy back onto a seven year old thread full of interesting insights on essentially the same subject. 
> 
> Here's my situation: 
> 
> 650 square foot single story Craftsman with R13 dense pack cellulose walls heated entirely with a wood stove (no outside air source) in PNW where--unlike many of you--our humidity mostly occurs in the winter. We have not hitherto had either a bathroom fan or a vent hood over the kitchen stove. I've been meaning to install both forever, but the complexities of managing the humidity this earlier thread hints at have kept me from actually buying any hardware or making much progress otherwise. 
> 
> I'm expecting to install both an exhaust fan for the single bathroom and one for the kitchen stove, and that part is straightforward enough, but my worry is that in the winter my fans may in use end up drawing high humidity outside air into the house through cracks around the exterior doors or windows(?) diluting any hoped for effects from the fans. 
> 
> Sidebar: minor evidence of mold can be found--with some scrutiny--in the tile grout in the bathroom, some on firewood pieces that cured outside and are brought inside, as well as on the underside of our daughter's cheapie mattress. The urgency around reviving this project is related to a hope that some of this potential for mold growth could be reduced. 
> 
> Oh and I have a(n Energystar-qualifying) dehumidifier as well, but have only run tests with it in the basement so far and am not excited about the electricity implications of running it continuously or for long stretches....
> 
> Any and all insights and suggestions are as always welcome and appreciated.
> 
> Reuben
> 
>> On Mon, Oct 25, 2010 at 6:48 PM, elitalking <elitalking at rockbridge.net> wrote:
>> ----- Original Message ----- From: "John Straube"
>> 
>>> Short answer again.
>>> ERVs do not dehumidify. The reduce the load on the dehumidifier when and only when it is lower RH indoors than a outdoors.
>> 
>> Yes.  Then if there is not another process to condense the vapor out of the air such as air conditioner, dehumidifier, or desicants, then there is no benifit to latent heat transfer.  However, when you mechanically dry the interior air, the ERV will preserve the value of that dehumidification. Right?  Strategies of night flushing cooler high relative humidity at night does not qualify.
>> 
>> Eli 
>> 
>> 
>> _______________________________________________
>> Greenbuilding mailing list
>> to Send a Message to the list, use the email address
>> Greenbuilding at bioenergylists.org
>> 
>> to UNSUBSCRIBE or Change your List Settings use the web page
>> http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org
> 
> _______________________________________________
> Greenbuilding mailing list
> to Send a Message to the list, use the email address
> Greenbuilding at bioenergylists.org
> 
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/greenbuilding_lists.bioenergylists.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/greenbuilding_lists.bioenergylists.org/attachments/20171216/4a22617e/attachment.html>