ULTRA-ZONE
HUMIDIFIERS
AN-134 Water Level Probe Replacement Instructions
REPAIRS SHOULD BE PERFORMED BY A QUALIFIED TECHNICIAN
To replace the water level probe in the “S” series steam
humidifier, you must unplug and shut down your steam
humidifier and allow it to cool. The water tank must be drained, the water supply, drain lines and electrical wiring must be disconnected and the unit removed from the duct. Pull straight up on the Green terminal block to disconnect It from the unit.
Place the unit on a flat working surface.
Using a phillips screwdriver, remove the two screws that hold the baffle plate to the tank. Lift the baffle slightly back to clear the water level probe and then straight up and out of the tank.
Unplug the automatic drain valve assembly from the side of the front cover. Snip the plastic wire tie that secures the drain valve wires to the main power cord. Now use an adjustable wrench at the brass “T” adapter to unscrew the entire drain valve assembly. DO NOT use the drain valve itself as leverage when removing or
Now use a phillips screwdriver and loosen the four screws securing the front cover and remove the front cover. You can now see the entire Water Level Probe.
Use a 5/16” nut driver to loosen the hex nut which secures the water level probe to the printed circuit board. Then pull the water level probe out of the plastic insulator just far enough to remove the second hex nut. Now you can gently pull the water level probe out and through the plastic insulator. Be careful not to damage the plastic insulator! Place a small dab of grease or Vaseline on the water level probe, to ease the water level probe out. Do the same on the new water level probe when
If the plastic insulator gets damaged, replace it. Otherwise, save the new plastic insulator for future use.
If the plastic insulator is damaged or, you want to replace it anyway, you must loosen and remove the ground screw at the top of the printed circuit board. This allows some play between the circuit board and the plastic insulator. Use pliers and pull the old plastic insulator out. Place a bead of clear RTV silicon around the square portion of the plastic insulator (between the sealing flanges). Position the plastic insulator at the square hole in the humidifier and using pliers and a side to side motion, gently pull the plastic insulator through the hole until the outside flange pops completely through.
Insert the new water level probe into the plastic insulator using a dab of grease to ease it in. Wrap the small cable tie around the plastic insulator and pull tight. Cut off the excess length. Screw one hex nut onto the water level probe until about 1/4” of the threads are exposed.
Push the water level probe up to and through the hole in the circuit board.
Now you can
Apply Teflon tape to the threads of the “T” adapter on the automatic drain valve. Screw the entire drain valve assembly back onto the drain fitting and tighten with an adjustable wrench. DO NOT use the solenoid valve itself as leverage to turn and tighten the assembly. Doing so will damage the valve. Tighten and position the drain assembly to the original position. Plug the drain valve molded connector back in on the side of the front cover until it snaps into place. Secure the drain valve wires with the short cable tie.
Review the entire project to be sure that nothing has been overlooked.
Now insert the unit back into the duct and secure it.
PLASTIC INSULATOR
WATER LEVEL PROBE
P/N 090376A0134P/N 090376A0134REV. B CopyrightREV© 2002. C
EWC Controls Inc.Field385ControlsHighwayInc33. 2630EnglishtAirportwn,RoadNJ 
