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Frequently asked questions about dehumidifiers.

A line of Santa Fe Dehumidifiers.
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Why isn’t an air filter effective against dust mites and mold?

Air filters are only effective on particles suspended in the air. The dust mite allergen is relatively large and dense compared to other particles, therefore, it does not stay airborne for a sufficient amount of time to travel a significant distance or through ductwork. Direct contact with these allergens in their breeding grounds is how individuals are exposed to them in the home. This is unaffected by air filtration devices.

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, however, can survive in this dormant larval stage for several months waiting for high humidity conditions to return.

What about running a smaller dehumidifier in just the bedroom?

A recent study showed that providing dehumidification to a single bedroom did not significantly reduce the humidity or the allergen levels present in the bedroom. The humidity from the rest of the house will overwhelm the efforts to dehumidify a single room.

How will the added heat affect my air conditioner?

Because the moisture load has been removed from the air conditioner, it is able to cool the air more efficiently. Homes that maintain lower relative humidities are more comfortable and require less cooling. The tendency is to set the thermostat at 78 to 80 degrees rather than 72 degrees.

Doesn’t adding fresh air ventilation increase my air-conditioning costs?

An increase in the amount of ventilation will increase the energy costs required to condition the fresh air to indoor levels. It is important to understand that some ventilation is occurring all the time. This is called natural ventilation. The actual increase in the overall rate and, in turn, the increase in utility costs is normally not significant.

How large an area can one unit handle?

A single Santa Fe dehumidifier will maintain relative humidity levels below 50 percent in air-conditioned structures up to 2,500 square feet, even if there is more than one air conditioning system. In larger homes, the Santa Fe XT155H can control up to 3,500 square feet or multiple units can easily be employed.

Why not buy two or more small residential dehumidifiers (for less money), instead of one Santa Fe?

There are several reasons why one Santa Fe dehumidifier is better than two or more residential dehumidifiers. First and foremost, two fifty pint residential dehumidifiers do not equal the water removal capacity of one Santa Fe dehumidifier in a basement application. The Association of Home Appliance Manufacturers (AHAM) rating system used for dehumidifiers reflects the performance at 80°F and 60% RH.

It is a mistake to assume that equal performance at these conditions means equal performance in the cooler conditions present in basements. In fact, most residential dehumidifiers, even those that contain a defrost feature, do not recommend operation below 65°F and in some cases 70°F. The performance of typical residential dehumidifiers at these temperatures is minimal if they function at all. Santa Fe dehumidifiers are designed to operate in temperatures as low as 56°F and will still remove over 60 pints a day at 60°F and 60% RH. This is the caliber of performance required to reduce the relative humidity below 50% and eliminate mold growth. Plus, the cost of operating one dehumidifier is less than operating two units.

Cost Comparison

Should you buy two standard appliance-grade dehumidifiers or one high-capacity dehumidifier to handle extremely wet conditions?

Purchase Price
Monthly Operating Cost
One 40-pint Unit $350.00 $36.00
One 25-pint Unit $250.00 $23.00
TOTAL $600.00 $59.00
One High-Capacity
Purchase Price
Monthly Operating Cost
One 100-pint Unit* $1,150.00 $20.00

In this example, you save $39.00 per month in operating costs by purchasing the high-capacity unit. After 11 months of operation, the electricity savings will pay for the higher purchase price of the high-capacity unit. From then on, you save money for each month of operation.

Comparison is based on 7.5 cents kWh, 24-hour operation, and 80°F 60% relative humidity.

To find out more about pricing for Therma-Stor dehumidifiers please call 1-800-533-7533 or contact us.

SOURCE: “Dehumidifiers and Humidifiers” published by MG&E, Madison, WI.