Relative humidity control?

I’ve never seen a relative humidity control before. What should this bee hooked to? The sellers stated they had no idea what is did if anything or what its hooked to.

This house had cadet heaters and base board heaters installed for heat in case it matters each with their own thermostats on the wall

I couldn’t get into the attic due to almost no clearance.

I am sure there are all types of configurations. Google is your friend.


I see that the units should be hooked to the ductwork this house has never had a furnace, no additional vents or intakes

I’ve seen humidity units on a furnace but never anything on a home with no form or furnace

So no ductwork at all? Because they just need an air handler (not a furnace) or they may be stand alone with no AC system, but they still need the ductwork.

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No furnace and no ducting that I could find, unless someone in the past blocked on some form of intake in the ceiling and I could not get to that point in the attic. I literally crawled on hands and knees on the trusses to try to see if something existed in the attic but felt VERY unsafe so i stopped.

Labeling in panel looks to be original with no obvious end use

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It could be a humidistat with contactors that close on the humidity drop or a dehumidistat with contacts that close on humidity rise. The contacts are probably rated for low or high voltage so literally anything could be connected to it, humidifier, dehumidifier, bath fan…

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Old humidistat/dehumidifier Controller. 20-80% R.H. Bathroom fan.

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