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Posted by Ted-san on November 24, 2008, 7:30 am
> > On Sat, 22 Nov 2008 08:23:34 -0800 (PST), Andy Energy
> > >On Nov 17, 4:15=A0pm, ollie2308_at_yahoo_dot_...@foo.com (ollie2308)
> > >wrote:
> > >> I have a gas forced hot air furnace with an Aprilaire 560 Humidifier=
. =A0I
> > >> would like someone to verify that the humidifier was installed corre=
ctly
> > >> and if so, explain how it works in this configuration.
> > >> The unit is installed on the return plenum via a square hole in the
> > >> plenum. =A0The unit sits in front of this opening. =A0There is a 6" =
round duct
> > >> that connects the left side of the unit to the supply plenum of the
> > >> furnace.. In this round duct there is a vent lever to control air fl=
ow.
> > >> During winter this vent is open
> > >> So if I understand this correctly... as warm air leaves the furnace =
"SOME"
> > >> air =A0is forced through the humidifier via the 6" duct. it passes t=
hrough
> > >> the water panel back into the furnace via the square opening in the =
return
> > >> plenum where it is re-heated and sent back through the supply plenum=
where
> > >> some gets returned to the house while some gets sent back to the
> > >> humidifier.
> > >> Am i missing something ? =A0this just seems inefficient.
> > >> Thanks
> > >> Ollie
> > >> -------------------------------------
> > >> ##-----------------------------------------------##
> > >> Delivered via =A0http://www.thestuccocompany.com/
> > >> Building Construction and Maintenance Forum
> > >> Web and RSS access to your favorite newsgroup -
> > >> alt.hvac - 26851 messages and counting!
> > >> ##-----------------------------------------------##
> > >A house that is built tight and ventilated right should have no need
> > >for a humidifier. =A0When is our building industry going to start
> > >building homes correctly?
> > >Andy
> > WTF?? Whe you heat air you dry it. Thus the need to ad moisture.
> > Where did you come up with that surmization?
> > Bubba- Hide quoted text -
> > - Show quoted text -
> ICheck the psychometric chart. =A0Raising the temperature of air does
> not add or remove water. =A0It only changes the RH. =A0The only reason a
> house dries out is because of air with less moisture is introduced
> through uncontrolled means. =A0Thus the air with enough moisture leaks
> uncontrolled out of the house.
> As to where the house gets its moisture from is the occupants. =A0The
> breath, perspire, bath and cook to name a few.
Your basic message can be correct, depending on the region. Here in
the mid-Atlantic, and other humid or mixed humid regions, over-
humidifying is a problem in some newer houses. In others, built leaky
(even with their "wrap around vapor barriers"), the winter humidity
levels can be uncomfortably low.
I always recommend that my clients monitor the indoor humidity to keep
it at safe levels, especially if they have central humidifiers.
What many are unfamiliar with is the structural damage that is often
caused by over-humidification. Every standard construction home has a
variety of leaks, particularly on interior walls where most builders
don't think it's important to air seal. That moist, interior air moves
up through those walls, out the cracks and into the attic. Recessed
lights are another particularly bad area for this. All the vapor
barriers in the exterior walls won't stop any of this moisture drive
from the inside from leading to condensation in the walls/ceiling with
the way most houses are built. All these leaks then cause more dry air
so the homeowner pumps more humidity into the home to compensate.
The worst situations I've seen is when people leave their filter cover
off with an attic mounted air handler. Now you're sucking a few
hundred CFM of cold, dry winter air into the system, which sucks the
moisture out of the air like nothing else while at the same time
forcing more moist air out through the cracks. A properly installed
and sealed HVAC system is one of the most important elements in
maintaining proper humidity and minimizing the chance for structural
damage due to moisture drive.
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>wrote: