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AN-135 Thermistor Probe Replacement Instructions
ULTRA-ZONE
HUMIDIFIERS
SUPPLEMENT TO THE ULTRA-ZONE ELECTRONIC STEAM POWER
HUMIDIFIERS MODEL # S2000 AND S2020
P/N 090376A0135 REV. C Copyright © 2002-2008, EWC Controls Inc., All Rights Reserved
To replace the Thermistor 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 re-installing the drain
valve assembly. Doing so will damage the drain valve and
void the warranty.
Now use a phillips screwdriver and loosen the four screws
securing the front cover and remove the front cover.
Use a 5/16” nut driver to loosen and remove the hex nut
which secures the water level probe to the printed circuit
board. Remove the ground screw at the upper right hand
corner of the printed circuit board. Remove the two small
phillips screws at the bottom corners of the printed circuit
board. The printed circuit board can now be laid flat and out
of the way. Be careful not to damage it! Locate the wires
from the Thermistor Probe and trace them to where they
connect to the printed circuit board. Pull the connector off of
the board.
Use two 7/16” combination wrenches, one as a backup on
the thermistor probe side, and the other wrench on the hex
nut. Loosen the hex nut on the Thermistor Probe assembly.
It will be a little tight due to the Loctite on the threads from
the factory. Loosen the nut all the way. Now cut both wire
leads in order to remove the nut and pull the thermistor
probe out of the tank. Discard the old Thermistor Probe and
the cut wire/connector.
Now remove the new Thermistor Probe and the other
accessories from the bag. Put the ”O” ring onto the threads
of the thermistor probe and all the way up to the base of the
Thermistor Probe. Feed the thermistor probe’s wire leads
through the hole in the tank and out the front. Position the
thermistor probe into the hole. Now feed one wire at a time
through the hex nut and thread the hex nut onto the
Thermistor Probe. Tighten the hex nut firmly.
Do not over tighten and damage the “O” ring.
Now insert each wire into the molded plastic connector until
it snaps in to place. Plug the connector back on to the
printed circuit board J2 pins.
Position the printed circuit board into place and secure with
the two small phillips screws at each bottom corner.
Make sure that no wires are pinched between the
transformer and the front plate. Adjust the wires as
necessary.
NOTE: Loose spade connectors can overheat and damage
the wires. Use pliers to re-tighten the spade connectors and
do not allow line and load wires to cross over each other.
Doing so will void your warranty.
Tighten the ground screw at the upper right hand corner.
Position the water level probe back into the hole on the printed
circuit board. Re-install the hex nut and tighten down firmly
while holding the water level probe leg straight down towards
the bottom of the tank. Loosen the hex nut and readjust if
necessary.
Now you can re-install the front cover. Make sure to line up
with the LED’s on the printed circuit board. Do not crush them
when pushing the front cover back on. You may have to
loosen the front cover screws a bit more. Press the front
cover back on all the way and tighten the four front cover
screws. Re-install the baffle plate and secure with the two
phillips screws.
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.
Re-connect the water, electrical and drain connections. Open
the water source valve and plug the steam humidifier into it’s
electrical outlet. Make sure the humidistat is calling for
humidity. Observe the operation of the unit and make sure
there are no water leaks.
REPAIRS SHOULD BE PERFORMED BY A QUALIFIED TECHNICIAN
THERMISTOR PROBE
“O” RING
CONNECTOR
HEX NUT
EWC Controls Inc. 385 Highway 33 Englishtown, NJ 07726 800-446-3110 FAX 732-446-5362 E-Mail- info@ewccontrols.com
P/N 090376A0135 REV. D 11/2011 Copyright © 2011, Field Controls Inc., All Rights Reserved
Field Controls Inc. 2630 Airport Road Kinston, NC 28504 PH: 252.522.3031 FAX: 252.522.0214
SUPPLEMENT TO THE ELECTRONIC STEAM POWER HUMIDIFIERS
MODEL # S2000 AND S2020