Why is my humidifier leaking and how do I fix it?

Your humidifier is leaking – don’t worry, we are here to help. Leaking is unfortunately a common problem that can happen in humidifiers, more typical in those that have not been properly maintained throughout the years. The following information applies to bypass and fan powered humidifiers, Aprilaire 400, 400A, 445, 445A, and 448 is not applicable to this article because it is drain-less and uses a pump or water reservoir system.

Common fixes for humidifier leaks

Water Backing Up Drain Line

Look at your drain line. Does it run on a slope to the drain? It should. If your drain line does not run on a downward slope it can form air bubbles inside, causing a water backup in the drain line which will then cause the water to seep out of the humidifier. 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.

Clogged Humidifier Filter or Scale Control Insert

Water panels (also known as an evaporator pad, water pad or humidifier filter, also referred to as “that thing that needs to be changed seasonally”) becomes clogged with mineral deposits, scale and other debris over time. Depending on how long you let the scale and debris build up it can end up physically blocking the drain opening resulting in a leak. Click here to find out which water panel you need for your system. – 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.

Solenoid Valve

Solenoid valve is the valve that allows water to enter into the humidifier. This is a very logical place to check if there is a leak. First things, you will want to make sure that you have the water flow set in the proper direction, following with the directional arrow printed on the valve. Another reason this may be leaking is from debris stuck between the valve’s plunger and the solenoid. The debris can keep the valve partially propped open causing the valve to leak once the water panel is saturated. To check the solenoid valve, shut the water off at the saddle valve and disconnect any power going to the unit, remove the solenoid and backwash with water under a light pressure. This should fix the problem unless the valve has been significantly damaged. In that case it will be necessary to replace the 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.

Water Pressure

The water pressure feeding into your unit should be no higher than 125 psi. Any higher than this can cause leaks.

Preventative measures to avoid humidifier leaks

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.