Wednesday, February 6, 2019

Energy efficient humidifier

Recently my humidifier stopped working despite relatively frequent maintenance (OK I could have done better).  They all require frequent cleaning and rinsing out with vinegar.  I bought it in a hurry a year ago because I was having sinus infections due to the very dry winter air in Maine and this was relatively inexpensive and off-the-shelf at my local pharmacy.  But I liked being able to stick my face in the warm mist to soothe my sinuses and I could add scent to it which was pleasant.  In retrospect I should have done more research and made a smarter choice to get a more energy efficient unit.

So this time I took my time and studied up on humidifiers and how efficient they are.  I found a very helpful blog post: "How Much Energy Does My Humidifier Use?" that really clarified things.  It verified what I already knew intuitively as an engineer.  Basically there are 3 types of humidifier:

1. Warm mist units that boil water to create steam.  This is the type that I had and it used over 250 Watts.  Not very efficient!  Actually this type are the least energy efficient.  Vicks make several models that I often see in the local pharmacy.

2. Evaporative units blow air across a wet wicking material using a fan that consumes around 50 Watts.  I had one like this years ago and had issues with it.  First the fan was quite loud - even on low.  

And second I had to replace the wick material every few months as they built up mineral deposits and mold.  Also, I did not like the idea of creating waste.  The wicks cost around $7-10 each and were not available in-store when I needed them.

3. Ultrasonic humidifiers use an ultrasonic device that agitates water so it creates water vapor directly, then a small fan pushes it out into the room.  These units are very quiet and relatively affordable - starting at around $45, but you can spend a lot more.  They use a lot less energy.  At 20-30 Watts they are the most efficient type of humidifier.

So I settled on a model I like:

This model TT-AH001 is made by TaoTronics, and has good Amazon reviews.  I did some energy tests and found these readings:
Standby 2W
Low 16W
Medium 20W
High 24W
I also like the control features - they have geek appeal.  Not many humidifiers in this price range have a built-in humidistats and this one let's you set the humidity in 5% increments and displays it in 1% resolution.  It has 3 speeds, none of which make any noticeable sound, I just hear the occasional burble as air comes up into the tank like you would hear from a water cooler.  It has a timer so you can set it to run a certain number of hours.  I only use it at night, so I just turn it on as I go to bed, and set the humidity to 40 and run time for 8 hours.  It works perfectly and maintains an accurate humidity.  And to cap it all off there's a blue LED night light "feature" that I never use, but the geeky designers just had to throw that in!

I also looked specifically for a model that has a flat top for the water tank.  Very few of them do, and it is really helpful to be able to set it upside down in the sink for filling where it will be stable while filling it.  I mean seriously, how are you supposed to fill this one (shown at left)?

As a product designer, I am shocked by the poor ergonomics of most humidifier tanks that have useless "sexy" curves that simply fall over when you place the tank upside down in the sink - requiring you to hold it while filling a gallon or more.  Some of them have dark plastic water tanks that don't let you see the water level which is really dumb!  This is another reason I chose the model I'm using, I can clearly see the water level.

What is impressive about all ultrasonic units is that they start generating cool mist almost immediately.  No waiting for the water to boil and the mist is quite visible so you know it's working.

I'm filling my tank with filtered water and find that it uses 1/4 to 1/2 tank every night in my small bedroom.  So I can go 2-4 days before needing to re-fill the tank.

I'm looking forward to a reduced electric bill next month.  I only pay for electricity for about 4-5 months of the year due to my solar panels, and it really bugs me to have to pay the utility company.

See my next blog post for a detailed evaluation of the power consumption of my humidifier.   

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