On Fri, 21 Jan 2011 18:28:24 -0700, Tony Hwang
wrote:
cubby wrote:
On Jan 21, 2:06 pm, wrote:
cubby wrote:
6%! Man, after the problems we saw at 22%, I would jump into the bath
before your skin peels off.
normal rh in a lot of places is under 10% for a good deal of the year. my
current local temp is 65 with a rh of 15% for today. summertime, it's
frequently under 10% for weeks.
Wow. I guess your body must adapt. Here in MN it's can get pretty
humid in the summer and bone dry in the winter. Once the dry air hits
you really notice it and it's not pleasant. Out of interest, where
are you?
Hi,
Same here in Calgary, AB, Actualy in winter RH can read negative.
What! It can read negative but I doubt it is negative. How would
that be possible? Wouldn't you need negative water or anti-water?
When I moved from ON in 1970 on company x-fer I used to have nose
bleed, too dry. Humidifier in this neck of wood is a must. Not
maintaining proper humidity can increase heating cost. When too
dry you feel colder. At present RH in the house is ~35%.
Oh yeah, that was a big reason I wanted the humidifier, to save money.
Although evaporating the water does drain heat** from the air that is
humidified, it is still cheaper if you turn the temp down, and most
people will because it feels more comfortable at lower temp with
moderate rather than low humidity.
When the furnace has been out of oil or broken on a couple occasions,
I boiled water on the stove, or ran the shower into a stopped bathtub
(don't let it overflow) and within 15 minutes it started to feel
noticeably warmer. Within 30 minutes the whole house felt warmer.
**Not only does a humidifier take heat from the air (the furnace air
in the case of a furnace-mounted humidifier) it takes a lot of heat.
The amount of heat needed to raise the temperature of a pint of water
is so much, I don't remember. The amount of heat needed to evaporate
that pint of water***, but still be at the same temperature that it
was, is 5 or 10 times as much. But it's still well worth it.
***It's called the heat of condensation or the heat of evaporation,
something like that.
Here it is
http://en.wikipedia.org/wiki/Heat_of_condensation
"Water is also commonly expressed as 539.423 calories per gram".
From the page on calorie:
* The small calorie or gram calorie (symbol: cal)[2] approximates
the energy needed to increase the temperature of 1 gram of water by 1
°C. This is about 4.2 joules.
* The large calorie, kilogram calorie or food calorie (symbol:
Cal)[2] approximates the energy needed to increase the temperature of
1 kilogram of water by 1 °C. This is exactly 1000 small calories or
about 4.2 kilojoules.
So iiuc, it takes 519 times as much heat to evaporate a gram of water
as to raise its temp from 70^F to 71.8^F. Despite that, it's well
worth it economically, if you turn the heat down too. You'll be more
comfortable than at the higher temp.