The Straight Dope

Go Back   Straight Dope Message Board > Main > General Questions

Reply
 
Thread Tools Display Modes
  #1  
Old 12-15-2009, 09:20 PM
CookingWithGas CookingWithGas is offline
Charter Member
 
Join Date: Mar 1999
Location: Tysons Corner, VA, USA
Posts: 9,689
Why can't I put hot water in my humidifier?

I have an evaporative humidifier--no heating element, no ultrasonic mist, just a filter to draw the water up and a fan to blow it into the air. It comes with an ostensibly permanent filter, which is several layers of metal grid (like mini chain-link fences) with some sort of material embedded that is supposed to make it bacteria resistant. The instructions say to fill it with cool water and specifically say not to use hot water.

These kinds of instructions always give you these inscrutable proscriptions without telling you why.

Why can't I use hot water?
Reply With Quote
Advertisements  
  #2  
Old 12-15-2009, 09:29 PM
kdeus kdeus is offline
Charter Member
 
Join Date: Apr 2004
Location: Maryland, USA
Posts: 165
A theory:

Hot water heaters hold water (duh) and heat it (duh) both of which a conducive to bad tastes and fungus/mold/ mildew/ metal from the water heater/ other nasty stuff in the water.

Cold water has spent less time in your system, having faster turnover, and may be considered "cleaner" than hot water.

This is what I heard regarding "Why use cold water in coffee machines & for cooking?"
Reply With Quote
  #3  
Old 12-15-2009, 11:59 PM
raindog raindog is offline
Charter Member
 
Join Date: Mar 2004
Is this a central system connected to a furnace or air handler?
Reply With Quote
  #4  
Old 12-16-2009, 05:25 AM
CookingWithGas CookingWithGas is offline
Charter Member
 
Join Date: Mar 1999
Location: Tysons Corner, VA, USA
Posts: 9,689
Quote:
Originally Posted by raindog View Post
Is this a central system connected to a furnace or air handler?
No, it's a portable unit. The filter is the second one on this page.
Reply With Quote
  #5  
Old 12-16-2009, 06:57 AM
Harmonious Discord Harmonious Discord is offline
Guest
 
Join Date: Apr 1999
It's burn hazard if it spills on somebody, so it's also a potential lawsuit. The hot water can also soften the plastics so the unit deforms.
Reply With Quote
  #6  
Old 12-16-2009, 07:13 AM
Sparky812 Sparky812 is offline
Member
 
Join Date: Aug 1999
Location: Great White North
Posts: 3,009
Quote:
Originally Posted by CookingWithGas View Post
It comes with an ostensibly permanent filter
The filter is not permanent and will require replacement depending on hours of use and water quality. The filter will eventually deteriorate and/or scale with minerals, sediment, etc. depending on your calcium hardness, Ph, alkalinity, lead contamination, etc..
Check your owner's manual and/or search for replacement filters for your make/model.

Quote:
Originally Posted by kdeus View Post
Cold water has spent less time in your system, having faster turnover, and may be considered "cleaner" than hot water.
Right! Hot water tends to contain more contaminants due to it's standing time in your pipes and hot water tank as well as it's lower Ph (more acidic)

Last edited by Sparky812; 12-16-2009 at 07:13 AM..
Reply With Quote
  #7  
Old 12-16-2009, 10:22 AM
raindog raindog is offline
Charter Member
 
Join Date: Mar 2004
I see no reason why you can't use hot water. I do not believe that hot water has more contaminants (enough to make any practical difference), nor will it warp plastic below 130. I'm hard pressed to believe that they make this distinction to avoid lawsuits.

The filter media you link to is the same material used in central systems and they are virtually never permanent. Depending on your water quality they will get limed up and need replacing.

I don't know why they say you can't use hot water and I'm reluctant to say it's ok as they may have some reason I'm unaware of.

This much I know: that filter media is the same media used in central humidifiers, and when they're installed in heat pumps we use hot water right from the water heater. So I can tell you that the filter media will be fine with hot water.

Maybe the guts of the system don't like hot water.
Reply With Quote
  #8  
Old 12-16-2009, 10:51 AM
troub troub is offline
Guest
 
Join Date: Jul 2000
It looks from the illustration in the manual that the tank sort drains into a tray at the bottom, from which the water is wicked up by the filter. Is that correct? maybe they don't want you to use hot water so that the steam doesn't rise from the base pan and condense on the fan, motor, or other parts in the main housing?
Reply With Quote
  #9  
Old 12-16-2009, 10:57 AM
raindog raindog is offline
Charter Member
 
Join Date: Mar 2004
Quote:
Originally Posted by troub View Post
It looks from the illustration in the manual that the tank sort drains into a tray at the bottom, from which the water is wicked up by the filter. Is that correct? maybe they don't want you to use hot water so that the steam doesn't rise from the base pan and condense on the fan, motor, or other parts in the main housing?
Good idea. That may be true.

The other thing that puzzles me about the OP is that the hot water will cool to ambient conditions long before it is all converted to water vapor, so I'm not so sure hot water will gain much.
Reply With Quote
  #10  
Old 12-16-2009, 04:00 PM
DirkGntly DirkGntly is offline
Guest
 
Join Date: Nov 2001
If your filter uses activated carbon (charcoal) as a filtering agent (and it likely does), then hot water breaks down the carbon portion of the filter. This means your filter FAILS, and fails QUICKLY...the broken-down carbon will plug up the more "mechanical" parts of the filter, rendering it useless. And that "specially treated to prevent the growth of micro-organisms" part is probably silver oxide, which kills bacteria - and is also not hot-water friendly.

Last edited by DirkGntly; 12-16-2009 at 04:02 PM..
Reply With Quote
  #11  
Old 12-16-2009, 05:30 PM
raindog raindog is offline
Charter Member
 
Join Date: Mar 2004
Quote:
Originally Posted by DirkGntly View Post
If your filter uses activated carbon (charcoal) as a filtering agent (and it likely does), then hot water breaks down the carbon portion of the filter. This means your filter FAILS, and fails QUICKLY...the broken-down carbon will plug up the more "mechanical" parts of the filter, rendering it useless. And that "specially treated to prevent the growth of micro-organisms" part is probably silver oxide, which kills bacteria - and is also not hot-water friendly.
You're speaking about air filters.

The OP linked to pads for humidifiers.
Reply With Quote
  #12  
Old 12-16-2009, 09:52 PM
sweetie pea sweetie pea is offline
Guest
 
Join Date: Aug 2009
CookingWith Gas--May I sidetrack a bit? Does it seem to you like this humidifier cools the surrounding area, maybe due to the fan blowing out not-very-warm air?

This was just not what I had in mind when I bought a humidifier to use in the middle of winter (the only season in these parts when anyone would actually want to add moisture to the air).
Reply With Quote
  #13  
Old 11-15-2010, 02:26 PM
ecenur ecenur is offline
Guest
 
Join Date: Nov 2010
I just recently had the same problem, started touching things I wasn't supposed too, the best thing to do is get someone who understands it is to check it out or tell you why. I have to end up getting a new furnace filter now because of that, which is also good because I really needed a new furnace and a clean furnace filter.
Reply With Quote
  #14  
Old 11-15-2010, 03:12 PM
lazybratsche lazybratsche is offline
Guest
 
Join Date: Feb 2006
Quote:
Originally Posted by Sparky812 View Post
Right! Hot water tends to contain more contaminants due to it's standing time in your pipes and hot water tank as well as it's lower Ph (more acidic)
Anybody have a cite for this? I've heard the claim repeatedly, but never backed up by actual water quality data. How many contaminants are in a plumbing system anyways, and how much difference does hot water make? I'm sure it depends on a number of factors like local water quality and the age of a given plumbing system. I'm just surprised that there isn't any good hard data on the subject (at least that I've found).
Reply With Quote
  #15  
Old 11-15-2010, 03:59 PM
boytyperanma boytyperanma is offline
Guest
 
Join Date: Dec 2005
It's probably just easier for them to say 'cool water' then to get into the details of how hot the water can be. Water no warmer then 130 degrees results in people seeing them as complex instructions rather then simple.

Maybe they only tested the equipment with cool water and don't want any responsibility for unpredicted events that could happen with hot water.
Reply With Quote
  #16  
Old 11-15-2010, 11:42 PM
commasense commasense is offline
Charter Member
 
Join Date: Mar 2003
Location: Las Vegas, NV
Posts: 5,161
No cite, but I've always assumed that repeatedly using warm water might eventually weaken the glue that holds the tanks together.
Reply With Quote
  #17  
Old 11-15-2010, 11:57 PM
outlierrn outlierrn is offline
Guest
 
Join Date: Nov 2005
Maybe it confuses the
Quote:
This humidifier has a Digital Humidistat which enables you to set desired maximum humidity level. Once this level is exceeded, the unit will shut off until the humidity level drops.
???

Last edited by outlierrn; 11-15-2010 at 11:57 PM..
Reply With Quote
  #18  
Old 11-16-2010, 12:05 AM
BigT BigT is offline
Guest
 
Join Date: Aug 2008
Quote:
Originally Posted by outlierrn View Post
Maybe it confuses the

Quote: This humidifier has a Digital Humidistat which enables you to set desired maximum humidity level. Once this level is exceeded, the unit will shut off until the humidity level drops.

???
I've seen this warning on much simpler devices that do not have such a feature, so I don't think that is it.

Last edited by BigT; 11-16-2010 at 12:05 AM..
Reply With Quote
  #19  
Old 11-16-2010, 12:11 PM
Tastes of Chocolate Tastes of Chocolate is offline
Charter Member
 
Join Date: Aug 2003
Location: slightly north of center
Posts: 4,259
Another possibility.
We use similar style humidifiers. The tank has a valve at the bottom, that allows the water to flow out of the tank and into the bottom pan. It looks like that valve is also part of the opening that you use to refill the tank.

Anyway, on ours that assembly has a couple of rubber gaskets, to prevent water from pouring out of the refill opening when you turn the tank upside down. Using hot water could soften the gaskets, allowing the 2 gallons of water in your tank to pour all over the floor.
Reply With Quote
Reply



Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 04:07 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Send questions for Cecil Adams to: cecil@chicagoreader.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Publishers - interested in subscribing to the Straight Dope?
Write to: sdsubscriptions@chicagoreader.com.

Copyright 2013 Sun-Times Media, LLC.