The Humidifier Solenoid Valve

Written on: March 25, 2022 by J. Paige Freeland

Solutions to common frustrations

A common frustration among homeowners who have installed and used a whole-house humidifier in their HVAC system is a malfunctioning solenoid valve. A solenoid valve is a control unit that uses electricity to automate the opening and closing of an orifice in the valve body. It allows, prevents or redirects the flow of water, gas or other medium. It comprises three main parts: the solenoid body, the electromagnetically-inductive coil and internal components (stem, plunger and spring).

Solenoid valves are used in washing machines, dishwashers, ice makers, refrigerators, vending machines, sprinklers and many other systems requiring water flow. As such, a whole-house humidifier utilizes a solenoid valve to control the amount of water flowing to the humidifier, specifically an electromagnetic two-way (inlet and outlet ports) solenoid valve.

Why do they fail?
There are several reasons a solenoid valve may stop working properly. The most common is that dirt or other contaminants become lodged in the valve seat, preventing the solenoid from opening or closing properly. A simple cleaning may be all that is needed.

Improper voltages, electrical malfunction or loss of power can also cause:

• Improper opening or closing,
• Corrosion,
• Burnt-out coils and/or
• Freezing in the open, closed or partially-opened position it was last operating in.

To solve these issues, check manufacturer-recommendations to make sure voltage to the humidifier and valve is correct.

Excessive fluid pressure differentials between the inlet and outlet sides of a valve can also cause internal valve components to buzz or clack during operation. To solve these problems, check fluid pressure and make adjustments as necessary.

A leaky valve usually means that the solenoid is stuck in the open or partially open position. This can be caused by a number of issues, but inevitably it creates leakage of liquid. Causes include degraded Orings, a plunger valve that does not close completely, cracks in the plunger valve seat or internal dirt particle buildup. The solution is to replace the solenoid valve.

Clean vs. replace
When debris collects in the valve seat of the solenoid valve body, it can simply be cleaned and returned to the humidifier. Corrosion can be removed by soaking the valve in vinegar and water. As with any mechanical apparatus, proper and proactive maintenance and care of a solenoid valve can extend product life and ensure predictable operation. On average, a solenoid valve should last between one and three years.

Does water supply matter?
Water supply can matter. Water with high sediment levels can clog a solenoid valve; installing a filter in the water supply line prior to the solenoid valve will reduce the number of particles reaching the valve. Where there’s water, there’s maintenance, even for a decorative fountain, a bathtub with jets, a faucet aerator or a humidifier. A humidifier provides a valuable service in providing healthier indoor air quality. Maintaining it will ensure it will do so for years to come. ICM