Tankless water heater and humidifier automatic model can they dance?

Consumer question:

I got this new humidifier and also I replaced to a tankless water heater. I wanted to use the humidifier in automatic mode and connected it to the hot water pipe. Since the flow is so low, the heater doesn’t kick in to warm the water. Condensation occurs on the plastic tube inside the humidifier and drips down on the floor. What are my options in using the humidifier as desired (auto mode)?

Aprilaires’ response:

Thank you for contacting us with regards to your model 600A Humidifier. Automatic mode refers to how the humidifier uses outdoor temperature to recalculate your humidity set point. As temperature drops, humidity settings should be lowered to compensate. The danger of leaving the humidity set point high as outdoor temperature falls is that your windows could start to collect that excess moisture in the form of fog or frost.
It’s not clear what you meant by condensation. In this application, liquid water is converted to vapor, but for that water to re-condense, it needs to come into contact with a very cold surface. There is a drain line coming from the humidifier, but that needs to be properly attached to a drainage system. There will be a constant trickle of water running out of the unit as it operates.
Please let us know if you have any further questions.

8 thoughts on “Tankless water heater and humidifier automatic model can they dance?

  1. Patrick Simon

    I also have a tankless water heater setup with my 600M. The humidifier fails to reach my desired %humidity level despite running non-stop. My suspicion is that the unit is getting cold water because the flow demanded by the humidifier is too little to trigger the water heater. How can I get more moisture out of my humidifier if it only gets cold water most of the time?

  2. Z

    I also have this SAME problem. I have a tankless system and the flow rate is so low that it never gets hot water from the tankless. I was goign to investigater buying an insinkerator instant hot water system to be the feed for the Aprilaire. Thoughts ?????

  3. Reginald

    hi, we are planning to replace our existing humidifier with an aprilaire but we are in the same situation, we have water tankless heater and afraid that the humidifier will not get hot water as it will not trigger the tankless.

    anyone found a solution? we would like to run the humidifier all year round (not just winter season) as it’s really dry here in Calgary and running in using just the blower will really help in putting moisture in the house.

    Hopefully there’s a solution for the tankless water heater and humidifier

  4. Sam

    Is there an issue with this situation? We are having a whole house humidifier installed today but do have a tankless water heater. Does it work with less than hot water?

  5. Dana

    A fan-type humidifier works best with hot water. It disperses water vapor into the air better than when it’s cold. If the furnace is running it may be fine, but when the fan is running without it the efficiency drops significantly.

    I have the same issue: a tankless water heater and a fan-operated humidifier. It sounds like a steam humidifier is the most logical solution. A steam humidifier generally is more efficient and a greater ability to cope with dryer conditions or a larger home.

  6. Steve

    I installed a 700A with a tankless, not even knowing that it wouldn’t work. Because it’s been such a cold season this year, hot water is taking longer, I installed a Laing recirc pump for the tankless. To my surprise my 700 now gets hot water because of the recirc pump. The pump was $$$ but helped me in two different situations.

  7. Kevin

    Hello Steve,
    Thank you for your feedback on the 700 humidifier. Our experience is that you do not get enough capacity with a tankless hot water heater to warrant using with the installation of the 600 or 700 humidifier. We have not tested for this application, but we are delighted to hear that you are getting the results you are from the pump.

    Thank you for giving us the opportunity to be of assistance.


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