Humidistats are used in a number of devices including dehumidifiers, humidifiers, and microwave ovens. Dehumidification can be accomplished with small residential dehumidifiers or using the building's air conditioning system. Their products include window, thru-the-wall, portable and ductless air conditioners, as well as dehumidifiers. Other products sold under the Coldspot brand included freezers, dehumidifiers, and window air conditioning units. They can also be used as dryers or dehumidifiers with modified attachments or mountings. There are two types of dehumidifiers - condensate dehumidifiers and desiccant dehumidifiers. Electric refrigeration dehumidifiers are the most common type of dehumidifiers. This involved sealing the armament, machinery and boilers against damp and installing dehumidifiers throughout. Spray dehumidifiers mix sprays of chilled water and air to capture atmospheric moisture. Ice buildup may be a problem, similar to problems with refrigeration dehumidifiers. If condensate water is handled automatically, most dehumidifiers require very little maintenance. It is also used in domestic and industrial chemical air dehumidifiers. Dehumidifiers extract water from air that passes through the unit. They can also be used to extract water from the air in dehumidifiers. The energy efficiency of dehumidifiers can vary widely.