Q&A: The Ideal Indoor Humidity Level In The Winter
Q: I have the humidifier set to the highest setting of 45 percent but the highest the humidity level I can get in the house is a reading of 35 percent. The house feels dry and I would like to increase the humidity in the house but I am unsure how to do this?
A: That's completely normal and expected. And actually with the current outdoor temperature, you should not set nor expect to reach more than 35%. Here's why. Below, please see the chart by the manufacturer. The outdoor temperature is in F. Currently it is close to -6C, 21F and in fact feeling much closer to 10F and based on this outdoor temperature, it is never recommended to go any higher than about 35%.
Going any higher than the above table numbers is strictly not recommended due to high chance of condensation on the windows, which will then be grounds for formation of mold and bacteria. Basically any humidifier is designed not to reach higher than the above numbers, based on outdoor temperature. And please keep in mind that with the reduction in outdoor temperature, it gets much drier (since with the drop in temperature, its capability also in holding more moisture also drops) and also the indoor humidity drops further due to longer furnace performance - further drying the drier air. Manufacturers design the output of humidifiers, having this and the above table numbers in mind and no homeowner should want nor expect to go above the above table numbers.
Please keep in mind that there is always a dilemma between having the perfect indoor humidity vs. not breathing mold and please keep in mind that going above the table numbers, makes breathing mold inevitable. Basically, as you know condensation happens due to dropping of temperature in the water vapour in the air. With the colder outdoor air, windows also get much colder which increases the chance of condensation on the windows. And with formation of condensation, you will inevitably have formation of mold and bacteria, which thrive in any dampness.