1500 watt heater. Enough?

myredracer wrote:

There is a tremendous amount of moisture released into the interior air from human bodies, cooking, showering and from pets. One human body alone on average release 5 cups per day into the air. No difference with electric heat or a furnace, there's a LOT of moisture that needs to be expelled somehow. An electric heater doesn't remove moisture. Remember, the warmer the air is, the more moisture it will hold so as an electric heater warms the space, the higher the RH will be (unless moisture is getting exhausted out).

The relative humidity goes down at the temperature goes up, assuming the actual amount of moisture in the air remains the same, because the air can hold more moisture. The fixed amount of moisture is thus a lower percentage of the amount the air can hold before it starts condensing. Obviously things that add moisture to the air like cooking and showering and breathing and sweating do increase the relative humidity, assuming no change in the ambient temperature.

The main problem in the winter is the lack of air exchange, which means the moisture builds up in a small space (like an RV). With a larger space like many houses, the problem is the opposite; there's sufficient air exchange that heating the replacement air causes a low relative humidity, and normal activities don't generate enough moisture to raise it to a reasonable level, so some form of additional humidification is helpful.