Fan humidifiers are not designed to run without furnace on heat or A/C mode because fan is not powerful enough to push air trough whole ducting. The fan humidifiers have control units connected to blower motor control so they turn on the same time and turn off together.

My 2 cents: 1) In the bypass humidifier - the water vapors are formed right at the water panel - this is better just because the vapors are distributed uniformly while evaporation occurs as the water is dispersed across the panel as opposed to the fan based one, where the water drips are transferred in the supply line, then evaporated. one point for bypass 2)They both should be installed at the supply, it relies on hot air to evaporate. Disadvantage here for the bypass is that the water goes through the furnace blower first, before getting in the house. As for the fan based humidifier the humidity skips the furnace - goes directly in the house. Less humidity loss and a more efficient way to introduce humidity in the system. Not sure how much is lost/how much it affects the filter and the blower. I would say 1 point for the fan based here 3)You mentioned the fan based being able to run without heat/fan from furnace? I would never do that - the water evaporated this way is minimal if any - I believe it would be a major waste of energy/water. I think these missing arguments are critical for this video

You shouldn't run your humidifier with out the blower motor running to circulate the moisture. Your going to rust out your duct work and cause mold growth...

Great video! Thank you for taking the time to put it together. One additional cost to consider of the bypass styling, the power to move air is supplied from the blower fan of the furnace. There is a parasitic loss of efficiency of the system when linking the output to the input of furnace. Just figured it is worth noting the efficiency loss of the bypass will likely nullify the cost increase of running the second fan. Another big advantage of the fan powered humidifiers installed in a basement is that the air in the basement is usually the air with the highest state of humidity in a home, so it will help circulate that into the rest of the home rather than the basement being a "catch basin" for higher humidity air.

Airflow on your bypass diagram is reverse. Air flows from supply side into humidifier then return side.

thank you for your clear and concise depiction of the differences between the two styles. this is exactly what i was looking for. now i know i definitely need a fan powered humidifier. u rock

I got a bypass because there was no room on the outflow side to put a fan-powered humidifier. Been working fine now for 7 years.

Thanks for no crappy muzak, liked and subscribed, very informative.

Question: Am I correct that the Fan Powered Unit delivers moist air through to all the supply vents, while the Bypass delivers to only one supply vent?

Would you recommend the fan powered humidifier if you don’t have room to install it on the supply and now you have to install it on the return. Even with hot water, my concern would be that the fan powered units throw out a lot of moisture (compared by bypass units), so it's not great to install on the return air side because you can get moisture collecting on the furnace filter, motor, circuits, and burner as it makes its way to the supply side. Thoughts?

I just installed a bypass one because the fan powered humidifiers required a larger footprint on the duct and I didn't have quite enough room.

thanks for the great video. Its a nice overview for people like me to decide which one to get. thanks

Wouldn’t use a fan powers humidifier if the ahu or furnace is located in the garage,attic or crawlspace as they use air from outside of the conditioned space in these examples.

Thanks a bunch😊😊

What about a steam humidifier like the aprilaire 800

What about the cost to own? How much power per year does the fan power consume and then add to your energy cost?

Thank you. Great explanation. I have a 2 mode heating system. That blows heat when the temperature drops and just blows air to recirculate intermittently. Will a by-pass work well with this type of system?

Preformance?

😬 can I install an exhaust fan on the bypass unit and drill holes to pull air :D just a thought

On the bypass you show air going into the unit when in fact it comes out because the blower motor is running. It than goes into the cold air return, past the heat exchanger and into the cold air return.

I personally would not put a nest thermostat on even my worst enemy's home.

You didn't address water waste, outdoor temp sensors or which control Manual or automatic is employed. A lot more to consider .

How about fan power type reliability/maintenance issue?

👍 thank you

It is performance....preformance?

James, how can I fabricate a fan for Aprilair 500?

Thanks great video

Double cost for fan power humidifier.

Excellent video!

Will Nest work for both these types of humidifiers?

how good are these with heat pumps?

The fan model makes your house cold when running