01—How to Troubleshoot Common Humidistat Problems

A man looks at a humidistat
  • 3-6 hours
  • Advanced
  • 200-1,000
What You'll Need
Pipe fittings
New transformer (possibly)
New humidistat (possibly)

A humidistat is used to measure humidity levels in your home or office. These devices can be part of the home heating and air conditioning system or portable humidistats can be used. The device will detect and measure the humidity levels, and cycle on and off when certain levels are reached. This can come in handy for those who have gas heat, as this can cause uncomfortable dryness. If your humidistat is not working as it should, here's how you can test it to find and solve the problem.

Step 1 - Check Voltage

Humidistat Controls on Amazon

Find the control panel for the humidistat. In most cases, this is found in the same area as your temperature controls for the heating system. Test the voltage using an ohm-meter. If there is 0 voltage reflected as you turn the knob on the humidistat, then the panel needs to be replaced.

Step 2 - Check the Settings

It's not uncommon for people to have the humidistat on a setting that isn't ideal, and then assume the unit isn't working. As a general rule of thumb, the humidistat should be set at 40 percent of the outdoor temperature. If you have a dehumidifier attached then you can set it at 65 percent of the outdoor temperature. Setting it too low will cause your house to become very cold, and setting it too high will not allow the house to maintain a comfortable humidity level.

Step 3 - Check the Water Lines

Whole house humidifiers are connected to your water supply. If there is a leak in the supply, or the connections have failed, the unit won't work. The humidifier should be hooked up to the closest cold water line relative to the humidifier. Follow the line until you find the connection. Check to ensure all the pipes are secure, and there is no water leaking. Use a wrench to tighten any loose connections. If you have a small leak, you can usually replace the fittings to solve this problem.

Step 4 - Check the Transformer

The transformer is a unit behind the humidistat that will reduce the voltage to the humidifier. The transformer is connected to the closest receptacle. Turn the power off at the breaker, and check to ensure the wiring is intact and the transformer is plugged in. If the wiring looks frayed, or otherwise damaged, you can replace either the entire transformer or just the wiring.

Step 5 - Contact a Professional

If you've gone through everything and the humidistat is still not working, it may be time to replace it or contact a professional to fix it. A new humidistat can be found for less than $100 at most home improvement stores, so if you are handy, it can be installed yourself relatively cheaply.

Not all humidistats are connected to a whole house humidifier. Some work in conjunction with your air conditioner. For these units, an authorized repair person should be contacted to ensure the system is running as it should.

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