During wintertime, the furnace air has been drying out the family
sinuses. Also, we have been sick a few times. While investigating, I
thought maybe it was a furnace issue.
I had a reputable furnace man out. He suggested having the furnace
cleaned/AC cleaned and each air duct cleaned. For a total of $500.
I have heard that the furnace/AC cleaning is a good idea. I have also
heard that duct cleaning is just a scam, because the filter picks up
the dirt that would be in the duct.
Any thoughts on that?
Being sick from time to time is part of life. During winter being close
together and dry air tend to increase the chance of illness.
Your furnace heats air and that decreases the humidity.
I suggest you contact a doctor about what your particular health issues
may be. The doctor may recommend correcting the humidity or may suggest
that you may have a mold - dust issue. Right now you are just guessing and
we are not doctors here and neither is your HVAC man.
It is a fact that there are cases where ducts should be cleaned, but not
often. There are also many cases where people are convinced they need ducts
cleaned when they don't need them cleaned.
Then again, an average family of 4 evaporate about 2 gallons of water
per day. In an airtight house, the relative humidity would quickly rise
to 100% in wintertime, limited by condensation on windows.
A 2400 ft^2 1-story house contains 2400x8x0.075 = 1440 pounds of air.
At 70 F and 100% RH, it would contain about 0.015832x1440 = 22.8 pounds
of water vapor. A family of 4 could increase the RH from 50 to 100% in
0.5x22.8/(2x8.33) = 0.68 days, ie 16.4 hours, or less, given a few more
green plants and indoor window surfaces cooler than 70 F.
Forget the furnace. Caulk the house.
An interesting thought, but I have never heard of a house coming
anywhere close to 100%. It would be a very unusual home, even a very tight
home to get up to a good 40-60% humidity level during winter in a cold
climate without additional humidification. Homes are not even close to
airtight and I sure would not want to live in one. The space station is
not a very comfortable place to live.
Caulk is not going to do it for most homes. I fear the realities of
home construction get in the way of your theory, even though the theory is
Eggxactly one of the missing details in that anal-ysis; and
besides, you wouldn't live for -long- in one! But then, you
wouldn't be able to get in, either. Hmm, unless you sealed it up
from the inside? <g> GAK!
Perhaps you live in an insular world.
Some Canadian houses are very airtight (eg 2.5 cfm for a 2400 ft^2 house.)
We recently saw one posting from a person in Ontario with such a house.
Some of us ridiculed his "confusion" as to how to reduce the indoor RH
with a small existing exhaust fan, without realizing that's a technique
recommended in Canadian building codes. Right now there's some concern
that people living in such houses are not aware their exhaust fans are
intended to be used for DEhumidification in wintertime.
Agreed, in the US.
In the US. People in other countries are smarter :-)
You might, with a simple automatic means for positive ventilation.
Caulk is a large part of the picture, along with
other means of air sealing and blower door testing.
If you caulk the outside and make the home that tight ( which isn't going to
happen in an older home unless you use a fire hose) you will encounter mold
and condensation in the walls and actually increase your heating bills due
to conduction. If your going to seal any structure you always do it on the
warm side and not the cold side.
On 8 Jan 2005 15:51:13 -0500, firstname.lastname@example.org wrote:
So - in a typical US house, when would one put in a Heat Recovery
Ventilator vs an Energy Recovery Ventilator (captures humidity) to
deal with air exchange and freshness issues? Is there an
infiltration rate that would suggest and ERV over a plain jane HRV?
Furnace cleaning's a good idea. They're all different, I guess, but in the
two I've owned, the motors got dusty and I don't think that's good for any
motor. You didn't mention what type of furnace you have, but if it's
oil-fired, you DEFINITELY want it looked at once a year.
As far as the ducts, unless you KNOW you have a mold problem (and it won't
only be in the ducts), it's pretty much a feel-good thing. It's cool to see
all the dust come out. But, if you're using the right filters, you're in
This will generate plenty of debate: In my informal and totally unscientific
research, with two furnaces in 20 years, I came to the conclusion that the
middle-priced filters (around $8) seemed to do as good a job as the more
expensive ones, and the cheapest ones were almost useless. I cannot document
my reasons, the experiment may not be repeatable anywhere in the known
universe. You also need to see what your owner's manual says about different
types of filters.
Politics: A strife of interests masquerading as a contest of principles.
The conduct of public affairs for private advantage.
Have your furnace and A/C checked and cleaned yearly.
Check your heat exchanger for cracks and/or have a CO test done.
Go to your doctor and see if you are sick.
Duct cleaning is always debateable. Have them show you a place or two
in your ducts that is dirty then you decide if you want them cleaned.
Cleaning ducts wont add humidity in your home.
Id be more interested in investing that money into a humidifier, air
filtering, UV light or other indoor air quality products. Those keep
on working/cleaning. The duct cleaning gets finished and the dirt
cycle starts all over again.
Just one exception, and a comment: First, there are companies that will
actually get the ducts clean, regardless of whether it's necessary. That
leads to the exception: We have a talk show here which sometimes has a home
inspector as the guest. He's mentioned a few instances where he's inspected
homes that sat empty for quite some time before being sold, and that
somehow, mice end up in the ductwork. The clue is the mouse crap, and you
don't want that gradually turning to dust and mixing with your air. If a
duct inspection turns up anything other than the expected dust deposits,
they're worth cleaning.
When I was a kid, my folks used to drop coins into the registers
so I'd clean them. It worked, and I was sure to reach in far
enough to get any and all dust/paper clips, etc. that collected
in there, especially that great big square return register! They
had to force me the first time, but after that ... <g>
One should not be so philopotemic
lest they be seens as disputatious.
You ever sit in your backyard and have a cool beverage? All around
you are mice droppings turning to dust and you are breathing them into
your lungs along with millions of decaying animals and plants. How
about having your soil cleaned by your friendly reputable furnace man?
On Sat, 08 Jan 2005 17:10:05 GMT, "Doug Kanter"
I had my ducts cleaned, but that is because I have had a lot of birds,
and they pulled a lot of debris out of the ducts.
The furnace should be inspected and cleaned every few years at least,
ducts maybe after a couple of decades, they don't get much dust under
'I have heard that the furnace/AC cleaning is a good idea. I have also
heard that duct cleaning is just a scam, because the filter picks up the
dirt that would be in the duct.
Any thoughts on that?'
Seasonal furnace and a/c cleaning and maintenance is a necessity if you
want to prolong the equipment life and greatly reduce a crisis . As for
ductcleaning, 'if' you have allergies to dirt, spore, animal dander,
mold, dustmites, etc....ductcleaning is worthwhile -- especially if your
home is old. There are numerous ways which contractors clean ducts
ranging from the scam way of holding a leaf blower to each register (yep
!) ...to drilling 1" dia. holes every 5 feet in the main ducts then
using special circulating brushes in conjunction with a super powerful
vaccuum on a truck followed up by spraying the inside of the ducts with
a mold killing agent. You need to find out EXACTLY HOW they do the
ductcleaning so you dont get taken . If done correctly, it can have good
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