Humidity and Comfort
Humid air can make a room feel as though it is significantly hotter than it is due to the way in which the human body cools itself. During perspiration, the sweat evaporates off the skin, taking with it body heat.
In a humid environment, water evaporates at a much slower pace. As such, humid climates inhibit the human body's ability to regulate its temperature, and thus the perceived temperature of the air can be much higher.
Dehumidifiers work to remove humidity from the air in much the same way that an air conditioner works. They do, however, have an added step.
A dehumidifier takes in air and blows it across cold Freon coils, which "sweat" the humidity in the form of condensation and collect it in a pan to be disposed of. Dehumidifiers then blow the cold air across warm coils to raise the temperature of the air back up to room temperature before blowing it back out into the room.
The result is dryer, and somewhat warmer, air.
Dehumidifiers have a compressor, a condenser, an evaporator and a fan, all running whenever the dehumidifier is running. All of these components require electricity, and, as such, all generate heat in some way.
Most modern dehumidifiers are efficient and well insulated and thus do not throw off significant amounts of heat from their core components. Regardless, however, the simple act of running an electrical device in a room will, over time, increase the temperature.
Dehumidifiers for Temperature Changes
Overall, a dehumidifier is a poor choice as a device to change the indoor air temperature. Air conditioners dehumidify the air as they cool it, so if you are looking for a less humid and less warm house, air conditioners are the way to go.
As a heater, dehumidifiers are not an energy efficient choice either. They make use of numerous components not necessary if your sole aim is to warm a room and use more electricity than a simple space heater.