As one of the largest online retailers for humidifier filters and parts, we receive calls from our customers about problems they’re having with their whole house humidifier. Leaking is a common problem with older humidifiers that haven’t been properly maintained. This article will discuss some possible causes of leaking and associated solutions.
Possible Causes:
1) Water Backing Up Drain Line – If the drain line doesn’t have a continuous slope to the drain, then it’s possible for the line to air lock. This causes a water backup inside the drain line. Removing dips and hills from the drain line and flushing it with water will help eliminate this problem. Replace drain line every year or as necessary in order to avoid this problem.
2) Clogged Humidifier Filter or Scale Control Insert – A clogged humidifier filter could cause the scale control insert to fill with residue and block the drain opening, which leads to a leaky humidifier. To prevent this problem you should clean your scale control insert and install a new humidifier filter. Click here for instructions if you’ve never changed your humidifier filter.

3) Solenoid Valve – Be sure the water flow through the solenoid valve is going in the correct direction. There should be an arrow designating the water flow direction on the valve body. If a piece of dirt or debris lodges between the valve plunger and seat on the solenoid, then the valve is unable to completely close. This causes the solenoid valve to leak. After shutting off the water supply at the saddle valve, disconnect electrical power and remove the solenoid valve. You should then gently flush the valve with water or try to blow out the blockage. This method is quite effective unless the valve seat has been permanently damaged. If this is the case, then it will be necessary to replace the valve.
4) Water Pressure – Water pressure above 125 pounds per square inch can also cause leakage. Check your water pressure and use a pressure reducer if necessary.
Avoid Leaky Humidifiers with Regular Preventative Maintenance
The best way to prevent these problems from occurring is by scheduling regular preventative maintenance. Contact a local HVAC technician and schedule annual tune-ups on all your heating and cooling systems. These tune-ups can help you save money by repairing worn or faulty parts before they cause costly damage.
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Note: The information above doesn’t apply to humidifiers with water reservoir systems or pumps.