There's a knock whenever the humidifier comes on or shuts off. What is the cause?

Wednesday, March 7, 2012 by Aprilaire Team

Consumer question:

There's a knock whenever the humidifier comes on or shuts off. What is the cause?

Aprilaires' response:

Thank you for contacting us with regards to your model 700 Humidifier. The noise you hear is the humidifier's solenoid valve (water valve) opening or closing. Normally, this valve makes a slight 'click' noise when doing this, but water pressure and the build up of water scale inside the unit can increase this noise. As a test, try turning off the water to the humidifier and then use the humidistat to turn the humidifier on and off. Listen for changes in the noise. Typically, the noise is quieter without any water pressure, but pressure is required to feed the correct amount of water through the unit.
Speak to your contractor about possible remedies if the noise becomes excessive. Anything from cleaning the valve to adding sound-insulating foam rubber to the valve can help dampen the nosie. In some cases, replacing the copper tubing with steel-braided rubber tubing or installing a shock-arrestor can help dampen the noise by absorbing the impact the water makes when the valve closes.

 

 

Comments for There's a knock whenever the humidifier comes on or shuts off. What is the cause?

Friday, January 3, 2014 by jp:
my model 700 has started clicking on and off numerous times prior to startup ?? why

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