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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8439
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I would like to disable the automatic on/off sensor that

Customer Question

Hi, I would like to disable the automatic on/off sensor that comes with the humidifier and use an external control unit that plugs into the wall. The proplem is that the external unit will tell the humidifier to stop and will cut power to the unit. However, when power is cut to this unit and then turned back on, it resets the fan speed to 0 and desitred humidity level to 0 and will not function unless I manually turn it back up. I need the humidifier to be on all the time and allow the external control to tell it when to shut on and off. Is there a way I can do this?
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.


Those controls are integrated electronic circuits... bypassing the sensor will be a complex electronics task even if that is one of your skill sets.

Turning the entire humidifier ON and OFF... from a separate wall mounted humidistat is possible however.

Let me know what you think of either option.

Customer: replied 1 year ago.
Thanks Phil, I was thinking that I could just find the hot and ground wire that supply power to the humidifier and bypass all the other controls, using the plug in humidstat to control when it turns on and off. I guess I would lose the fan speed option if I did that, but I might be OK with that.You menitioned using a seperate wall mount humidistat to control it would be possible. How is that diferent from the plug in on I'm using now?Thanks,
Expert:  Phil replied 1 year ago.

Hello again,

A number of companies make line voltage humidistats. You would simply run the black wire that feeds the receptacle that the humidifier is plugged into through the humidistat.

From go from here without a time limit as needed.

Thanks for letting me work with you. When we are finished, if my answer has been polite, professional,and thorough, please click one of the ratings . If you still need help let me know!. Expert is not paid for assisting you until you rate answer. Feel free to follow up for30 days at no additional cost.

Customer: replied 1 year ago.
Thanks, ***** ***** was able to figure out how to get the unit to function as described with my plug in humidistat. I opened up the control unit on the humidifier and found the point on the circuit board where the 'Hot' wire was soldered. I then jumped it directly to one of the fan speed points on the same circuit board. This bypassed the internal humidistat and now when the power is supplied, the fan immediatly runs at medium speed until the power is cut off/on via the external humidistat.The internal humidistat was not very use able and had no ability to adapt to the environment to maintain a constant level of humidity. You had to guess what the humidity needs were at any given time by choosing one of 3 fan speeds and one of 4 levels of humidity saturation levels.
Expert:  Phil replied 1 year ago.

That is superb work on your end. Keep an eye on it to be sure there are no untoward consequences.


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