I switched from three standalone humidifiers to an AprilAire 700 and it works so well that I haven’t had to run the standalone units anymore. It works really well and way less maintenance once you get it installed.
Steam is mainly about control and consistency. It actively generates vapor, so output isn’t tied to furnace runtime and it maintains target RH far more reliably in cold weather. Drip/bypass units like the Aprilaire 700 are cheaper to buy and run, but their effectiveness drops in cold conditions, they only work when the furnace is on, and evaporation leaves minerals behind—causing scale, frequent pad changes, and fine mineral dust entering the airstream, with the issue becoming worse as water hardness increases. Over long periods, inhaling fine particulates is associated with chronic airway irritation, can worsen asthma or other respiratory conditions, and may contribute to long-term lung function decline.
Steam still needs maintenance, but it keeps minerals contained in the canister. Cost-wise, bypass units are roughly $20–$40 per season, while steam is closer to $100–$200. In many cold, dry climates, bypass units struggle to get past ~30% RH, while steam remains reliable.
Definitely go with the Aprilaire 700 series for that setup - they're solid and handle that square footage well. Since your heat pump runs most of the time you'll want one that doesn't need crazy high temps to work properly and Aprilaire nails that
I have one and like it. I have a basic aprilaire bypass unit. If I had the space though I would have gone with the aprilaire 700. And if you have the circuit available and easy to wire, a steam unit is the most ideal.
Let's break it down.
The bypass and fan powered humidifiers need heat to get their published evaporation rate. Your furnace heat call is where you'll get that heat most of the time. If you install it with the automatic humidistat you get the option to run outside the heat call which is going to do a better job maintaining your humidity. Unfortunately you have a tankless water heater and the blower activation should be run with hot water. You can run with cold water but your evaporation rate will be significantly lower than rated.
The steam humidifier can provide up to 35 gallons of steam per day, it doesn't need a heat call to operate and it doesn't need hot water. It will use 3.8kWh during operation. So if it ran 8 hours a day for a month your bill would add almost 1000kW to your electric bill.
I would personally put in a model 600 with an automatic humidistat with blower activation.
And just for clarity:
Model 600 large bypass
Model 700 fan powered
Model 800 steam humidifier
Top Humidifiers on Reddit
1
LEVOIT
Superior 6000S Smart Evaporative Humidifier
75% positive of 83 users
Smart, large capacity; cleaning and whole-home coverage polarized.
4kVHS
