Why you need a Dehumidifier
Controlling Moisture
Moisture build up is a real problem in NZ’s heavily insulated modern homes.
A family can generate up to 15 litres of moisture per day through breathing,
cooking, bathing, heating and clothes drying. In summer months, this moisture
builds up in wall linings, framing, roofs and furnishings. In fact, moisture
will build up anywhere it can be absorbed. Our outdoor lifestyle compounds the
problem. In summer we tend to open doors and windows, which leads to more humidity
being absorbed into our houses. View the problems caused by moisture.
Reducing Dampness & Mildew
The moisture our houses absorb manifests itself in dampness and condensation.
Dampness can cause deterioration - to our curtains, furniture and expensive
appliances. It can also damage our home causing rotten window sills, wall linings
and peeling wall paper, as well as mould in wardrobes, on clothes and a general
feeling and smell of dampness in our environment. The new MJ-E20PX & MJ-E26RX
have a new feature called “Mildew Guard” that will further decrease the presence
of Mildew and Mould in your house.
Asthma and Allergy
New Zealand statistics for Asthma and some allergies are amongst the highest
in the world with one in six New Zealanders having Asthma. 70-80% of Asthma
in New Zealand is associated with Allergies. Many of these problems can be linked
to the moisture content of our homes.
Air Purification
A good dehumidifier will help remove dust, pollens and smoke from the air by
utilising an Air Purification system. Removal of these from our surroundings
can be of benefit to asthma/allergy sufferers and those with respiratory problems.
Before examining the problems moisture causes we should examine where this moisture
comes from. Each of us will produce approximately 2.5 litres per day of moisture
through normal household activities - cooking, washing, showering, and even
breathing. Add to this the fact that "flue-less" gas heaters can produce up
to two litres of moisture for every litre of gas burnt, and it soon adds up.
This problem is compounded in summer. New Zealanders tend to open their homes
up in summer in order to keep cool. In many cases the humidity outside in summer
can be higher than that inside. This means that when summer humidity is high
this moisture is often absorbed into our homes.
The other problem we face is one called "developed country" syndrome. This is
experienced by many developed nations that have warm comfortable homes that
are well insulated, carpeted, and Airtight. Our homes literally don't "breathe".
So where does all this moisture go?
It is absorbed into our wall linings, bedding, furnishings and clothing.
Come winter and the colder weather and we start to see evidence of this moisture.
The best example of this is on our windows. If the temperature inside is warm
and humidity levels are high, condensation will appear on the windows which
are colder. On really cold nights this condensation can be dramatic with water
running down the window, and accumulating on the sills, walls and floors of
our homes. Other noticeable evidence of dampness is a cold, musty smell in rooms,
mildew in wardrobes and on curtains, and damage to wall linings, peeling wallpaper
and rotting timber!
This all sounds very serious and it is. Repairs to structural timber, new curtains
and damaged furnishings and appliances are expensive to replace. For most people
these are the visible signs and consequences of moisture in our homes and are
sufficient motivation to attempt a solution.
But the problems don't end there! There is another, perhaps more serious consequence
of moisture in our homes - that of the effect on our health.
The health issues are varied. The two main problems are Asthma and Allergies.
There is now a known link between Asthma and the prevalence of Dust Mites in
our homes.
So what does this have to do with moisture?
Dust mites thrive in conditions of high humidity. In fact they require a direct
water intake from their environment in order to survive and prosper. Therefore
if we are able to control the level of humidity in our homes we are much more
effective in reducing dust mite activity. If we can slow down dust mite activity
we can help decrease the risk of Asthma and some allergies. For more information
on Dust Mites and Allergies/Asthma refer to the Allergy/Asthma link on this
page.
So what is the solution to controlling the moisture in our
homes?
Many people believe that insulation and ventilation will solve the problem.
These measures will help, but they wont solve the problem. Take a typical home
in winter. Insulation has retained much of the heat generated by our heating
devices. As well as retaining the heat the moisture has also been retained and
as a result humidity levels are high. As soon as the temperature drops condensation
occurs. So heating and insulation are not the answer.
What about ventilation?
Again, this will help but will not solve the problem. When we expel the warm,
moist air we lose a great deal of the heat that has been produced by our heating
appliances. As well as this cold, often moist air from outside is circulated.
This cold air from outside can also cool surfaces such as glass which will speed
up the condensation process! This in turn means we need to reheat this cold
air to stay warm - and the cycle begins again. Some ventilation is recommended
- such as venting clothed dryers, and use of fans in bathrooms and kitchens
to remove moisture generated by cooking and bathing.
One of the most effective ways of reducing moisture levels in our homes is a
dehumidifier. The advantages are that moisture levels can be reduced and then
maintained to a desired level, without being hugely expensive and invasive.
A further advantage is that reducing the amount of moisture in the air results
in lower heating bills as dry air is easier to heat than moist air!
Allergy Awareness Association
Heres what the Allergy Awareness Association have to say:
“Irritated watery eyes, runny and stuffy noses,
sinuses, skin problems, respiratory difficulties and asthma can often be due
to an undiagnosed allergy, many of which can be caused by house dust mites and
mould. Some estimates have up to 30% of all people being allergic to house dust
mites. In a warm, damp environment, you have an atmosphere in which dust mites
thrive. Dust mites live in our furnishings, bedding, carpets and clothing and
can cause havoc if you have an allergy. Allergy Awareness Association recommends
a good dehumidifier be used to assist in reducing humidity levels in our homes.”
We know there is a link between Allergy/Asthma and Dust Mite activity. This
is a real problem in many homes as the following statistics show:
The following is adapted from paediatrician Dr Allen Liangs' address
at Allergy Awareness Associations AGM in 1999 - courtesy Allergy Awareness Association.
Allergy Awareness Association recommend a good dehumidifier be used in helping
to control dust mites in our homes - here is why!
In the most prevalent species are the Dermatophygoides pleronyssinus
and its near relative D.farinae. Scientists use Latin names to describe how
the mites can be bred under laboratory conditions - Dermato means skin, or dander
of animals, including human skin. Phagoides means to eat or to consume. Pleronyssisis
comes from the same root as the word pterodactyl (the dinosaur with feathers)
and means feather, while farinae means flower. So the house dust mites in our
homes love and thrive on human and other animal skin droppings, and flour which
can be found in biscuit and breadcrumbs. In fact, these mites also love a nice
serving of mould as part of their diet as well.
As dust mites are totally blind, they have evolved a system to decide whether
particles they have just come across are food or waste that they have already
extracted all nutrients from. After they have ingested a parcel of skin dander,
they envelop it with a wrapping of their own digestive proteins. These enzymes
extract all the nutrients they need before discarding the wrapped package as
facal pellets.
If the mites then come across these pellets later, they can recognise the chemical
signature of mite droppings and avoid ingesting them again. Unfortunately, allergic
people can be sensitive and react badly to the enzymic proteins in these facal
pellet wrappers.
The pellets are about the same size as our red blood cells and shaped like a
collapsed muffin. They are relatively heavy for an allergenic particle, and
when disturbed can stay in still air for around half an hour (compared with
cat allergens, which can stay suspended for up to 75 days!). Exposure to the
dust mite is more intense for children and adults in a horizontal position on
our mattresses because of proximity to the source of dust mite facal pellets.
Old mattresses easily carry up to a million dust mites. Given enough food supply,
each mite can process and package four facal pellets per day. With four million
allergenic particles disturbed when people engage in bed activities, it is no
wonder there is not only shortness of breath, but also wheezing and hard breathing
associated with such activities! It pays to keep our mattresses clean!
House dust mites cannot drink. They obtain water partly from their food but
the bulk of water needed is obtained by a mechanism of hygrophilic (water loving)
crystal in their armpits. These finely structured crystals can obtain enough
water for the mite when the relative humidity in the air is above 60%. The mite
must tone down its activity if the relative humidity drops below this figure.
When the relative humidity is above 80% year round, which explains the very
high levels of dust mite counts in this city environment. The hygrophilic crystals
also protect the dust mite from dehydration when conditions are dry. Crystals
can be damaged (by being frozen). Such damage increase the rate of defaccation
which can hasten the death of the dust mite when exposed to sunlight. Persistent
heat above 60 degrees C also kills the mite and its eggs.
For children who are genetically prone to developing allergies, exposure to
dust mite allergens is likely to result in dust mite allergy. The chances of
allergy development depends not only on the degree of exposure, but also the
timing as well. It appears that exposure during the first six months of life
is most likely to initiate the allergy. Continued exposure and dose of exposure
can result in allergy diseases. Data from the ETAC study of children with chronic
eczema indicated that confirmation of house dust mite allergy from skin prick
testing is dependant on the maturation of the skin, with less than 1% positive
skin reaction at age one, and 13% at age five.
The study also confirmed previous finding of the relationship between having
wall to wall carpeting and the development of this allergy. For example in Spain
where the climate is usually warm and moist, there is almost universal association
between hose dust mite allergy and carpeting in those genetically prone. In
England where 95% of homes studied have wall to wall carpets, about one third
of the children studied have confirmed dust mite allergy. However, in Scandinavia
very few households have carpet and almost none of the children studied have
mite allergy.
Therefore, control of house dust mites consists of the following:
What is Humidity?
The water vapour contained in the air.
What Humidity range is recommended for my home?
Between 40-70% RH.
My Mitsubishi dehumidifier only removes small amounts of
moisture in cold weather. Why?
A dehumidifier's ability to remove moisture is dependent firstly on the amount
of moisture in the Air. If dehumidification has reduced the humidity to a low
level, less moisture can be removed from the air. It is also more difficult
to remove moisture from cold air than warm air.
I use a Mitsubishi dehumidifier, but why is there still condensation
on the windows in the mornings?
The dehumidifier can take a few weeks to remove the moisture in your home to
an acceptable level. Setting the unit to high and leaving it on 24 hours a day
best does this. We also recommend the unit be moved from room to room. After
a few weeks the unit can then be set to one of the auto modes 50/60/70% and
this will maintain the humidity to your desired level. On cold mornings there
often is a small amount of condensation on the windows but this will evaporate
quickly.
On cold nights it is important to have the dehumidifier running whilst the house
is warm - this will result in more moisture being removed than if you start
the dehumidifier before you go to bed, and will result in less condensation
forming on the windows.
Can I leave my Mitsubishi Dehumidifier turned on 24 hours
a day?
The unit can be left running unattended. It will switch off automatically when
the tank gets full or the required humidity is reached.
Why does the noise level fluctuate?
During operation the compressor in the unit will turn on and off. This will
be noticed by an increase in volume.
Why does the defrost lamp light up and the fan stop?
When the room temperature falls below 15 degrees C, the unit may go into defrost
mode. Defrost mode will occur every 30 minutes approx, and will last for a few
minutes. During defrost mode the fan will stop but the compressor will keep
going.
Can I drink the water collected in the tank?
It is not advisable to drink this water as dust and other impurities can collect
in the tank. This water however is excellent for houseplants.
My Mitsubishi dehumidifier is noisy - is it faulty?
It is important to remember that all dehumidifiers make a noise due to compressors
and fans operating. Mitsubishi Oasis dehumidifiers are in fact the quietest
products available in NZ. However, they do still make a noise. Noise levels
are dependent on many factors. Place the unit on a firm, level surface. A unit
placed on a wooden floor will make more noise than a unit on carpet.
Damage during transportation in our experience is the most common reason for
excessive noise - it is important that your dehumidifier be handled carefully
during transportation and should always be transported upright. The unit will
also make more noise when used on a high fan speed setting.
Nothing turns a hot day more oppressive than high humidity. In rooms that
don't really merit an air conditioner, or to cut down on the use of an air conditioner,
simply run a dehumidifier to make living more bearable.
The recommended humidity level inside your home during the summer is around
40-50%, and high indoor humidity can make you uncomfortable and adversely affect
your home. Musty smells, peeling wallpaper, warped wood, blistering paint and
moisture dripping from water pipes indicate excessive humidity and the need
for a dehumidifier.
Dehumidifiers remove excess humidity by drawing moist room air over cold
refrigerated coils. The moisture in the air condenses into droplets as it passes
over the cold surfaces in the dehumidifier and into a container. "Dried" air
then returns to the room at approximately its original temperature.
To get the most out of a dehumidifier, clean its coils every year and frequently
remove the collected water. Keep the unit clear of windows and doors where dehumidified
air will leak out. Finally, to get maximum airflow, position it away from windows,
walls and large furniture, like sofas or dressers.
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If you frequently smell musty odors or feel damp spots on the floors or
walls of your basement, laundry room, or storage area during warm, humid weather,
you need a dehumidifier.
The recommended humidity level inside your home during the summer is around
40-50%, and very humid conditions over an extended period can leave you uncomfortable
and adversely affect your home. Musty smells, peeling wallpaper, warped wood,
rusting tools, blistered paint and moisture dripping from pipes are signs of
excessive humidity. These conditions are most common during spring and summer.
Dehumidifiers remove excess humidity by drawing moist room air over cold
refrigerated coils. The moisture in the air condenses into droplets as it passes
over the cold surfaces in the dehumidifier and into a container. "Dried" air
then returns to the room at approximately its original temperature. For best
results, the unit should be located in an area closed to outdoor air and where
air movement in and out of the unit is not restricted.
Here are some features to look for on many of today's models:
- Automatic turn-off switch that shuts unit off when container is full
- Signal light indicating that container is full
- Adjustable "fill" control that stops unit at the desired "fill" level
- Automatic humidistat that maintains the desired humidity level
- Automatic defrost control which shuts compressor off when freeze-up develops
and turns it on again when ice is melted. (This occurs when temperature and
relative humidity are low.)
- Combination dehumidifier/heater to warm a room that tends to be chilly
frequently
- Quiet-running compressors and fans
- Easy-to-reach controls
- Easy-to-clean grille, condenser coil and container
- Rustproof, spill-proof container with built-in handles for portability
- Drain-hose fitting to let water run continuously to a convenient drain
- Wheels or rollers for easy mobility
- Rust-resistant cabinet.
While control or built-in features may increase a model's convenience of operation,
they also raise its price. Consider each option carefully before you decide
it is worth purchasing. But the most important consideration is "water removal
capacity," the number of pints of water removed from the air in 24 hours.
Energy efficiency is important in dehumidifiers. Differences of only 85 watts
may add 20 kWh daily to your summer electric bill. Some models let the fan run
continuously to circulate air back to the humidistat. Since in most situations
the moisture content will be the same throughout the enclosed area being treated,
this may be an unnecessary energy expense.
Place the dehumidifier at least 6 inches from the nearest wall where air can
flow freely to and from all sides. Avoid locating it in a room corner or near
a large piece of furniture. Shut all doors and windows to the area to be dehumidified.
For the first few days of operation, turn the humidistat, if the model has
one, to drier or "extra dry." This aids moisture removal from furnishings as
well as room air. After the area has dried, adjust the humidistat to your particular
comfort level.
Before you empty the water pan or bucket, turn the machine off and also disconnect
the power cord. This eliminates any possibility of electric shock if you spill
water and there is a fault in the grounding system of the unit or your home
wiring. Be sure the area, the unit, and you are dry before you reconnect the
cord.
Dehumidifiers operate most effectively at air temperatures about 70 F. At temperatures
below 65 F frost may form on the coils (which are kept cold to condense as much
moisture as possible). If this happens, shut it off, and wait for it to defrost
before running again. Frost cuts down air circulation so the dehumidifying process
does not work, and may damage the coils. This problem usually occurs in cool
basements in spring or fall; check the appliance if temperature hovers near
that point.
As water condenses out of the air, heat is given off, raising the temperature
slightly in the area around the appliance. This warmer air results in a lower
relative humidity.
Cleaning
Dehumidifiers need little upkeep or care. The following simple procedures
are sufficient:
Always unplug the power cord before cleaning the unit. For regular cleaning,
dust the grilles or louvers with a soft brush or the dusting attachment of a
vacuum cleaner. Either dust the cabinet or wipe it with a damp cloth. Every
few weeks, scrub the inside of the water container with a sponge or soft cloth
and a mild detergent to discourage the growth of mold, mildew, or bacteria.
At least once each season, remove all dust and lint from the cold coils with
a soft brush.
Always plug a dehumidifier into a three hole grounded outlet. If there is
none where you want to put the unit, make sure you install one properly. Using
extension cords is not advised because if an extension rests on a damp floor
or if water spills on it, is a shock hazard. If you must use an extension cord,
be sure it has a three-hole receptacle and three-prong plug for grounding. If
a three-hole, grounded outlet is not available, convert it following our instructions
and grounding properly. This is particularly important for a dehumidifier because
it may be operated on a damp floor that could conduct electricity and because
it collects water, which could spill and cause an electrical accident. Never
remove the third prong from a dehumidifier plug; to do so invites an electrical
accident.
A dehumidifier makes use of the fact that water tends to be individual
gas molecules in the air at higher temperatures but condensed liquid molecules
on surfaces at lower temperatures. At its heart, a dehumidifier is basically
a heat pump, one that transfers heat from one surface to another. Its components
are almost identical to those in an air conditioner or refrigerator: a compressor,
a condenser, and an evaporator. The evaporator acts as the cold surface, the
source of heat, and the condenser acts as the hot surface, the destination
for that heat.
When the unit is operating and pumping heat, the
evaporator becomes cold and the condenser becomes hot. A fan blows warm, moist
air from the room through the evaporator coils and that air's temperature
drops. This temperature drop changes the behavior of water molecules in the
air. When the air and its surroundings were warm, any water molecule that
accidentally bumped into a surface could easy return to the air. Thus while
water molecules were always landing on surfaces or taking off, the balance
was in favor of being in the air. But once the air and its surroundings become
cold, any water molecules that bump into a surface tend to stay there. Water
molecules are still landing on surfaces and taking off, but the balance is
in favor of staying on the surface as either liquid water or solid ice. That's
why dew or frost form when warm moist air encounters cold ground. In the dehumidifier,
much of the air's water ends up dripping down the coils of the evaporator
into a collection basin.
All that remains is for the dehumidifier to rewarm
the air. It does this by passing the air through the condenser coils. The
thermal energy that was removed from the air by the evaporator is returned
to it by the condenser. In fact, the air emerges slightly hotter than before,
in part because it now contains all of the energy used to operate the dehumidifier
and in part because condensing moisture into water releases energy. So the
dehumidifier is using temperature changes to separate water and air.
Distilled water is created by boiling water, which releases steam. This
steam is then condensed, forming liquid water that is collected in a clean container.
This process not only produces pure water since any minerals or other substances
in the water are left behind, but also the heat sterilizes the water so that
live fungal and bacterial pathogens are not present in the distilled water.
A dehumidifier works by simply condensing water from the air (from the water
vapor that is present in household air) and collecting it. Since this does not
involve boiling the water, the water is not sterilized. In fact, older dehumidifiers,
which may not have been cleaned out, can feature many fungal spores in the equipment
and in the water that is collected (since fungal spores are naturally found
in damp air anyway).
So, while the water collected in the dehumidifier may not contain problematic
minerals and chemicals, such as sodium or chlorine, that might be in your town
water supply, it can contain high levels of microbial contamination and it not
suitable for drinking or for hydroponic systems--unless it is boiled first.
Humidifiers & Dehumidifiers Energy saving
tips Purchase a low wattage unit. If
you’re comparing dehumidifiers with the same capacity, check the wattages on
the nameplates. A lower wattage unit that does the same job is the better value.
Humidity makes you feel warmer. Use a humidifier in
the colder months. With the proper humidity level, you’ll be able to turn your
thermostat down to a lower temperature, save energy and still feel comfortable.
Dehumidifiers remove moisture. Use a dehumidifier in
the warm, humid months to remove moisture from the air. A dehumidifier works
best when air can circulate freely through it. Place it away from walls and
bulky furniture. Reducing moisture and humidity in your home. Place
dehumidifier in the area with the highest humidity. For
safety reasons, don’t place it directly in water or near your sump pump.
Check for frost build-up. If your unit is running in
temperatures less than 70º F, check
it occasionally to see if frost is building up on the coils. If so, turn the
unit off until the frost melts and the room is warmer. Clean the unit. Dust or vacuum the dehumidifier at least
once a year before you plug it in. If your unit is difficult to clean, check
the owner’s manual.
How do humidifiers
work and what is the daily output of water? Are they silent? There
are two basic types of humidifiers, passover and heated. IN the case of
the passover models, air passes over the surface of the water in the humidifier
and gains humidity. A passover humidifier is completely silent and actually
decreases slightly the noise transmitted thru the hose.
The amount of water used per night is a function of the temperature and humidity
of the air coming from the humidifer, the water temperature in the humidifier,
the amount of air flow, and the amount of water surface area the humdifier provides.
Most users will find they have used 1/4 to 1/2 cup during a night. This is usually
enough to keep the airway moist and comfortable. A heated humidifier greatly
improves the amount of water vapor being delivered to the user.
Air can only hold so much moisture for a given air temperature. This
measure is the relative humidity. If the air is saturated with moisture,
we say it is at 100% relative humidity. That is like when you are in a
steamy shower with clouds of moisture in the air. If the temperature in
the room is lower, it will steam up even more since the air can't hold as
much moisture before it condenses (changes from vapor to liquid) on a
surface. The air in a room will will lose moisture to a dehumidifier
because it is cooled below the existing temperature and cannot hold as
much moisture as it did at the warmer temperature. The cold surface will
cool the air, and the moisture in the air will condense from vapor to
liquid onto the cold surface. To condense a vapor to liquid, it must give
up a certain amount of energy. This is absorbed by the chilled plate in
the de-humidifier. (An example is the mirror in a steamy bathroom with the
shower running.)
Tabletop humidifier works off the principle of evaporation. More energy efficient
than warm-moisture humidifiers because there is no heating element.
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