Why can't I control my inherited whole-home humidifier?
Many units are wired to run whenever the furnace is on, but manufacturers and installers refuse to provide technical support or information to new homeowners. Without this access, owners cannot adjust their humidity levels and are forced to guess whether exposed wires belong to critical missing parts, like the outdoor temperature sensors required to prevent mold.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
- 1Tracing the wires from the solenoid valveDid this help you?
- 2Posting pictures of the furnace wiring online for adviceDid this help you?
- 3Buying and wiring a new manual humidistat on the return ductDid this help you?
- 4tracing wires from the control unit to the outside wallDid this help you?
- 5asking online forums to identify exposed wiringDid this help you?
- 6buying a cheap replacement sensorDid this help you?
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“The humidifier is currently run by the furnace and water is supplied when it is running but we have no way to control the level of humidity.”source ↗
“I tried calling Lennox, and they can’t provide technical support to me, a technician would have to call into technical support, the installer won’t release any information to be unless the previous homeowner gives the ok”source ↗
“I’ve been scared to use the humidifier because of potential mold issues, but I’m seeing now that the AprilAire unit is supposed to have an outdoor temperature sensor integrated to prevent excess moisture issues.”source ↗
“After way too much time digging around and tracing wires, I think this is my outdoor temperature sensor?”source ↗
“I believe the outside sensor part is supposed to be in a shrink-wrapped sleeve of sorts, right? Will just the two exposed wires still work?”source ↗
Where this came up
People with this problem also raised
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- 5Can I drain my dehumidifier into an unknown basement pipe?
- 2Why does a secondhand dishwasher need to be hardwired?