Poor Man's Humidifier
Info-technology Library
chapped lips, etc. Humidity could be wrought by purchasing an
expensive humidifier; but I offer a cheap alternative:
Get a large jug that can hold a lot of water but which has
a somewhat small opening. (i.e., a gallon container with a
lip of 1-3 inches). Fill it up with water, then roll up a
newspaper and put it into the water. Place it in front of, or
near, a heater vent. (this is assuming you have a blow-heater).
Clever, eh? Just remember to change the newspaper from time to
time. I've noticed this... stuff that begins to appear around
the top after a week or two; don't know if it's healthy.
131J50000-WelchBJ(DR3215)283
: If you're like me, winter (dry) weather makes your skin itch,
I like this idea, but here's mine: I use a drying rack for laundry,
and extra humidity I just soak a towel and drape it on the rack before
going to bed. Works for me...
-bjw
--
Bryan J. Welch, AT&T Bell Laboratories - br...@dr.att.com - N0SFG
----- I have seen the future, and it is a prototype. -----
Chris Orgill
(Info-technology Library) wrote:
> If you're like me, winter (dry) weather makes your skin itch,
> chapped lips, etc. Humidity could be wrought by purchasing an
> expensive humidifier; but I offer a cheap alternative:
>
> Get a large jug that can hold a lot of water but which has
> a somewhat small opening. (i.e., a gallon container with a
> lip of 1-3 inches). Fill it up with water, then roll up a
> newspaper and put it into the water. Place it in front of, or
> near, a heater vent. (this is assuming you have a blow-heater).
>
> Clever, eh? Just remember to change the newspaper from time to
> time. I've noticed this... stuff that begins to appear around
> the top after a week or two; don't know if it's healthy.
Some Australian native plants and shrubs are relatively dim about
controlling water uptake. Melaleucas (Paper Barks) are a good
example. Just have a few of those around your house and keep them
well watered and they'll act as excellent humidifiers.
I live in the UK at the moment. Anyone got a good idea for a
cheap de-humidifier :-)
Chris Orgill
Nick Pine
>...there are specific building codes (in the US anyway) about time limits
>for complete air exchange for health reasons.
I don't think so. I have heard of some codes which require 5-10 cfm
per occupant, but that does not depend on the size of the room, as you
seem to imply. The current 1993 BOCA code just says:
1205.2 Ventilation Required: Every room or space intended for human
occupancy shall be provided with natural or mechanical ventilation.
>If you get too fanatical in an already well insulated house, you can end
>up with sick-building syndrome.
It's very hard to be that fanatical. It's almost impossible to seal up an
existing house so there is less than 5-10 cfm per occupant. Consider an
average two story 30 x 30 house with 1 air exchange per hour. That corresponds
to a ventilation rate of 240 cfm. I'm an engineer, and I've pressure tested
and sealed up a few dozen houses. If you try as hard as you can, you probably
can't seal up a house like that to less than 0.2 ACH, corresponding to 48 cfm.
Air-air heat exchangers are one cure for sick buildings, eg the following.
Article 41584 of sci.energy:
From: ni...@vu-vlsi.ee.vill.edu (Nick Pine)
Subject: Chimney air-air heat exchangers
Date: 1 Nov 1995 08:53:31 -0500
Organization: Villanova University
Does anyone use a woodstove or fireplace chimney as an air-air heat exchanger?
Seems like this might work with a bare fluepipe running up through a masonry
chimney, or a triple wall air-cooled "all-fuel" fluepipe with cold outside
air coming down the from the outside, to a point lower than the air intake
for the fireplace, to supply combustion/ventilation air which is heated as
it travels down the outside of the fluepipe.
I suppose this is a "counterflow air-air heat exchanger" as explained on
page 3-4 of the 1993 ASHRAE Handbook of Fundamentals. If the hot flue gas
enters the fluepipe at a temp Thi, say 68 F (when there is no fire) and the
cold outside air enters the top of the chimney at a temperature Tci, say 32 F,
and the amount of airflow is, say, 50 cfm, and the fluepipe is 6" in diameter
and smooth and 16' long, what will the temperature Tco of the cold air that
enters the house be, and what will the heat exchanger efficiency be?
The area of the fluepipe is A = 16' x pi x 6"/12" = 25 ft^2. The U value of
the smooth fluepipe surface is about 1.5 for each side, if the air and flue
gases are flowing slowly, so the overall U value is 1.5/2 = 0.75 Btu/hr-F.
The Number of exchanger heat Transfer Units is approximately
NTU = AU/Cmin = 25 ft^2 x 1.5/2/50 = 0.375,
E = NTU/(1+NTU) = 0.375/1.375 = 0.27
= (Tco-Tci)/(Thi-Tci) = (Tco-32)/(68-32), and the incoming air temp is
Tco = 32 + 0.27 (68-32) = 42 F.
We might do better with earth-coupled air for winter ventilation, but
if we need a chimney anyway, why not use it in this way?
If we roughen the fluepipe somehow and make the chimney fit around the pipe
more closely, and increase the air velocity to V = 2 mph, using a small
blower for incoming air, the thermal conductance of the fluepipe airfilms
would increase to about
U = 1/(1/Uinside + 1/Uoutside) = 1/(1/2 + 1/(2+V/2) = 1.2,
and the NTU would increase to about 25 ft^2 x 1.2/50 = 0.6
and the heat exchanger effectiveness increases to
E = 0.6/1.6 = .375, so
Tco = 32 + 0.375 (68-32) = 45 F.
We could turn on the blower when the fluepipe gets hot, with a thermostat,
or when the humidity rises, in an airtight house.
What will the incoming air temperature be when there is 600 F flue gas going
into the chimney, and how much of this "waste heat" can be recovered in Btu/hr?
One could use the formula above, substituting 600 for 68. How much wood could
we save during an 8 hour fire every day over a 200 day heating season, with
one of these chimneys, assuming a cord of wood contains the heat equivalent
of 100 gallons of oil at 100K Btu/gallon?
The outgoing flue gas temp, Tho, would come from the formula
E = (Thi-Tho)/(Thi-Tci) = (600-Tho)/(600-32) = 0.375, so
Tho = 600 - 0.375 (600-32) = 387 F,
which is greater than 212 F, so the water in the flue gas would exit as
vapor, but the creosote may condense. So the fluepipe joints should be
installed "downhill," lapped so the creosote runs back into the woodstove.
Nick
Dominick Dell'Erba
>(Nick Pine) wrote:
>> Some estimates hold that 40% of the winter heating bill for a house is
>> due to air leaks. The better the insulation, the larger the fraction
>> that air leaks contribute to the heating bill. It's a good idea to go
>> around caulking the house on the inside some very cold and windy day.
>> Visit the basement, even, and feel for cold air coming in around pipes,
>> etc, and fix those leaks with stuff some fiberglass insulation, etc.
>
>While this is true, there are specific building codes (in the US anyway)
>about time limits for complete air exchange for health reasons (my father
>is a structural engineer). If you get too fanatical in an already well
>insulated house, you can end up with sick-building syndrome. If you've
>got a brick house, no need to worry. :-)
>
>
>fleur
>--
>Fleur Diana Dragan / fl...@clark.net -- It's my name. Really, it is.
> Belly dancers make favorite wives.
If you want to seal a house in the fashion known as "tight", caulking
around all cracks and outlets etc., even if it is brick, it may have
tightly installed insulative sheathing, then you should have a furnace
which uses outside air for combustion. As well as a water heater that
does the same. And a furnace which uses a mixture of outside air, to
introduce fresh air into the home.
Not ver frugal though, except in the long run.
Dominick