Humidity Control

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					Humidity Control
The critical factor for healthy indoor air quality
  and why dehumidification is so important.
Higher Humidity = Dust Mites and Mold                                           Beyond Air-Conditioning
Dust Mites                                                                      A conventional air-conditioning system is not designed to control
Dust mites live in upholstered furniture, carpets, and mattresses. They         humidity below 50 percent on a continuous basis. Air conditioners are
feed on shed human and animal skin scale. In order to stay hydrated,            actually air coolers. Warm air is passed across cooled refrigeration coils
dust mites must absorb their moisture needs from the air. If the relative       that absorb heat from the air and pump it outside. This leaves the air
humidity is below 50 percent, dust mites dessicate (dry out). Their             cooler. When moisture condenses on these cooling coils, extra heat
appetites increase as the relative humidity climbs. This is significant         is released. New high-efficiency air conditioners struggle to control
because their fecal material is the source of the dominant dust mite            humidity while also providing high energy efficiency.
allergen. Ninety percent of the population that experience any allergy-
                                                                                Air-conditioning is controlled by a thermostat that reacts to a demand
based sensitivities react to the dust mite allergen.
                                                                                for cooling. If it is 72 degrees outside and raining, there is not a need
                                   Once produced, the allergens settle          for cooling, but there is a significant demand for dehumidification. The
                                   into fabrics and carpet. The dust            graph below shows the average weekly relative humidities for three
                                   mite allergen remains potent for             groups of homes involved in a study of dust mites.
                                   approximately 9 months. Individuals
                                   come into contact with the allergen
                                   after some activity like vacuuming,
                                   dusting, or making beds has “stirred-
Normal Mite                        up” the area and caused the allergen
                                   to become airborne. Due to its size and
                                   shape, the allergen remains airborne
                                   for only a short period of time. For
                                   this reason, air duct cleaning and
                                   air filtration devices are ineffective
                                   methods of combating the dust mite
                                   allergen. Vigorous vacuum cleaning
Desiccated Mite                    and use of acaricides can offer some
                                   short-term reduction in allergen levels.
According to studies conducted at Wright State University by Dr. Larry
Arlien, dust mite infestations will be eliminated if the relative humidity is
consistently maintained below 50 percent.

                                                                                The study was conducted in Dayton, Ohio. In that climate, there is
Molds are a fungi. They only require high humidity (70 percent or
                                                                                a summer demand for cooling. Indoor relative humidites below 50
higher) and an organic-based material on which to feed. It is no
                                                                                percent are common throughout much of the rest of the year. The
surprise that they are plentiful in humid climates. Cooler surfaces
                                                                                second chart shows the live dust mite counts for the same group
                                 create a perfect breeding area for
                                                                                of homes. A count of 100 mites per gram of dust is the accepted
                                 mold because the relative humidity
                                                                                threshold where a significant reaction to the allergen occurs. Even
                                 at their surface will be near 100%.
                                                                                the short period of time the air-conditioned house is above the 100
                                 The surface may even be wet with
                                                                                live mites per gram of dust threshold is sufficient to “dose” the house
                                                                                for a year, because the mite allergen remains potent for up to nine
                               The most common molds are the                    months. Recently this study has been repeated on a larger scale with
                               species Alternaria, Epicoccum,                   EPA funding. The results of this study further confirm the relationship
                               Penicillium, and Cladosporium.                   between humidity control and dust mite elimination.
                               Individuals may react to the mold’s
                               spores or to mycotoxins (a toxin)
                               released by the mold. Unlike the dust
                               mite allergen, mold spores remain
                               airborne for significant periods of
                               time and are always present, to some
                               degree, in outdoor air. Most mold
                               spores measure 5 to 10 microns
                               in size and can be filtered out of
                               the air with the proper efficiency
filter media. Mold growth can be eliminated in the home through
humidity control that maintains reduced relative humidity levels and
prevents cooler surfaces from becoming damp.                                                           Air Conditioned & Santa Fe/Ultra-Aire
How Santa Fe and Ultra-Aire                                                  natural ventilation. The actual increase in the overall rate and, in turn,
                                                                             the increase in utility costs is not normally significant.
Dehumidifiers Can Help
Therma-Stor LLC created the SANTA FE and the ULTRA-AIRE to have              How large an area can one unit handle?
the capacity to maintain relative humidities below the recommended           A single SANTA FE or ULTRA-AIRE will maintain relative humidity levels
maximum 50 percent level, even in structures with fresh air ventilation.     below 50 percent in air-conditioned structures up to 2,500 square feet,
The best way to combat the problem of humidity migrating through             even if there is more than one air conditioning system. In larger homes,
the roof, walls, and floor is to pressurize the building with dehumidified   the ULTRA-AIRE 150-H can control up to 3,500 square feet or multiple
air. This strategy involves bringing a measured amount of outdoor air        units can easily be employed.
into the structure and dehumidifying it before it enters the living areas.
An equal amount of drier indoor air will escape from the structure to        Why not buy two or more small residential dehumidifiers (for less
equalize the pressure. This ventilation strategy, provided by the Ultra-     money), instead of one SANTA FE or one ULTRA-AIRE?
Aire system, prevents humid outdoor air from infiltrating the structure      There are several reasons why one SANTA FE or one ULTRA-AIRE is
and offers the ventilation recommended by health experts. The Ultra-         better than two or more residential dehumidifiers. First and foremost,
Aire has been incorporated into numerous American Lung Association           two fifty pint residential dehumidifiers do not equal the water
Health Houses.                                                               removal capacity of one SANTA FE or one ULTRA-AIRE in a basement
                                                                             application. The Association of Home Appliance Manufacturers (AHAM)
                                                                             rating system used for dehumidifiers reflects the performance at 80°F
Frequently Asked Questions about                                             and 60% RH.
Santa Fe and Ultra-Aire Dehumidifiers
                                                                             It is a mistake to assume that equal performance at these
Why isn’t an air filter effective against dust mites and mold?
                                                                             conditions means equal performance in the cooler conditions
Air filters are only effective on particles suspended in the air. The dust
                                                                             present in basements. In fact, most residential dehumidifiers, even
mite allergen is relatively large and dense compared to other particles,
                                                                             those that contain a defrost feature, do not recommend operation
therefore, it does not stay airborne for a sufficient amount of time
                                                                             below 65°F and in some cases 70°F. The performance of typical
to travel a significant distance or through ductwork. Direct contact
                                                                             residential dehumidifiers at these temperatures is minimal, if they
with these allergens in their breeding grounds is how individuals are
                                                                             function at all. The SANTA FE and ULTRA-AIRE dehumidifiers are
exposed to them in the home. This is unaffected by air filtration devices.
                                                                             designed to operate in temperatures as low as 55°F and will still
                                                                             remove over 60 pints a day at 60°F and 60% RH. This is the caliber
How much will the SANTA FE or ULTRA-AIRE cost to operate?
                                                                             of performance required to reduce the relative humidity below
The cost to operate the SANTA FE or ULTRA-AIRE depends on the
                                                                             50% and eliminate mold growth. Plus, the cost of operating one
moisture load present. If there is a 65-pint load per day in the house,
                                                                             dehumidifier is less than operating two units.
it will cost approximately $20 per month to operate the SANTA FE or
ULTRA-AIRE to remove this amount of water. In comparison, it would           * Madison Gas and Electric, Dehumidifiers and Humidifiers; page 4. Based on $0.075
                                                                             per kWh, 24-hour operation at 80°F, 60% RH.
cost about $59 per month to remove the same amount of water using
                                                                             ** J ALLERGY CLIN IMMUNOL., Vol. 99, num. 1, part 2, pg S161. E Fernandez Caldas,
one 25-pint and one 40-pint residential dehumidifier.*                       WL Trudeau, DK Ledford, RF Lockey, Tampa, Florida.
Why is 50 percent relative humidity so critical?
The survival of adult dust mites is limited to 4 to 11 days in relative
humidities below 50 percent. Dust mites in the protonymph stage,                                         Indoor Air Pollution: An Introduction
however, can survive in this dormant larval stage for several months                                     for Health Professionals is a booklet
waiting for high humidity conditions to return.                                                          sponsored by the American Lung
                                                                                                         Association, the Environmental
What about running a smaller dehumidifier in just the bedroom?                                           Protection Agency, the American Medical
A recent study showed that providing dehumidification to a single                                        Association, and the Consumer Product
bedroom did not significantly reduce the humidity or the allergen levels                                 Safety Council. It outlines a variety of
present in the bedroom.** The humidity from the rest of the house will                                   sources of indoor air pollution and,
overwhelm the efforts to dehumidify a single room.                                                       for each, lists symptoms, diagnostic
                                                                               possibilities, remedial action, and comments.
How will the added heat affect my air conditioner?                             In the section entitled “Health Problems Caused By Animal Dander,
Because the moisture load has been removed from the air                        Molds, Dust Mites, Other Biologicals,” recommendations include:
conditioner, it is able to cool the air more efficiently. Homes that              • Provide adequate outdoor air ventilation to dilute human
maintain lower relative humidities are more comfortable and require                 source aerosols.”
less cooling. The tendency is to set the thermostat at 78 to 80                   • Keep relative humidity below 50 percent.
degrees rather than 72 degrees.
                                                                               In the “Comments” section, it is further stated:
Doesn’t adding fresh air ventilation increase                                     • A number of factors allow biological agents to grow and be
my air-conditioning costs?                                                          released into the air. Especially important is high relative
An increase in the amount of ventilation will increase the energy costs             humidity, which encourages house dust mite populations to
required to condition the fresh air to indoor levels. It is important to            increase and allows fungal growth on damp surfaces.”
understand that some ventilation is occurring all the time. This is called

             Santa Fe Free-Standing Dehumidifiers
             • Large capacity                                 Santa Fe Advance                                        Santa Fe HC | Our largest
                                                              Energy efficient and                                    capacity, free-standing
      • Low temp operation                                    low profile design. This                                dehumidifier. High powered
             – down to 56ºF                                   unit is sized for 2200                                  and strong. This unit is sized
                                           90 PINT            sq. ft. typical.                       135 PINT         for 3200 sq. ft. typical.
          • Optional ducting

              • Gravity drain
                                                              Santa Fe | Removes                                       Santa Fe RX | Extremely quiet
                                                              more water per unit                                      operation makes it an ideal choice
      • No buckets to empty
                                                              of electricity than                                      for offices, residences, schools, and
                                                              any other qualified                                      libraries. Our only unit with a built-in
 • Ideal for basement – attic                                 dehumidifier in the                                      condensate pump and 20 feet of
    – crawlspace applications                                 Energy Star® Program.                                    drain hose add extra convenience.
                                  100 PINT                    This unit is sized for         86 PINT                   With an optional secondary filter
               • Automatic                                    2500 sq. ft. typical.                                    housing, you may choose HEPA,
            humidity control                                                                                           carbon-plus pleated media, or
                                                                                         high efficient (95%) filters. The SF Rx is not ducting capable.
                                                                                         Requires 65º+ temps for optimum performance. This unit is
                                                                                         sized for 2200 sq. ft. typical.

 Ultra-Aire Whole House Ventilating Dehumidifiers
 • Designed to utilize existing
ductwork to distribute fresh,
filtered and dehumidified air
       throughout the house.

     • Pressurizes the home
       with dry air when the
optional fresh air ventilation                                            90 PINT                                                          135 PINT
          feature is selected.      UA-90H                                                    UA-135H
                                    Horizontal configuration. This unit is                    Horizontal configuration. This unit is
          • Optional fresh air      sized for 2200 sq. ft. typical.                           sized for 3200 sq. ft. typical.
   ventilation helps to dilute
      indoor pollutants and
      maintain high oxygen
            content in the air.
                                    Vertical configuration.                                                                                145 PINT
         • Optional 95% high        This unit is sized for
          efficiency filtration                                                               UA-150H
                                    2500 sq. ft. typical.
                                                                                              Horizontal configuration. This unit is
                                                                                              sized for 3500 sq. ft. typical.
              • High capacity                                             100 PINT

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