Service bulletin
Unlocking stuck water valve
TWH-G2-11
| 2400E, 2400EO, 250SX, 250SXO, 635ES, 635ESO
Introduction
If there is little or no
fl
ow coming out of the heater, the inlet
screen is clean and the unit is plumbed correctly, then the water
valve may be stuck closed. To cycle the water valve to the open
position, follow the steps below.
Tools needed:
Very
small
fl
at head screwdriver
Unlocking water valve
1. Turn the on/off button on the front of the heater to the off
position (to the left).
2. Locate the water valve inside the lower half of the heater where
the cold inlet water comes in. Locate the plug connection that
comes from the control board and plugs into a connection
coming from the water valve. This plug has 8 multi colored wires
coming into each connection.
3. Disconnect the multi colored wire connections coming from the
water valve.
4. On the connector coming from the control board and starting at
one side you will see a black wire, then a red wire, and then a
green wire (on older models, this wire was brown). Using a very
small screwdriver, push down on the silver tab to release and
disconnect the green wire (or brown for older models) from the
connector.
5. Leaving the green wire (or brown wire for older models) discon-
nected, plug the 2 connectors back together.
6. Turn the heater on (to the right). You should hear the water valve
opening up. Leave the heater on for 5-10 seconds and then shut
the heater off (to the left).
7. Unplug the wire connections and replace the green wire (brown
for older models) from where it was pulled out.
8. Plug the 2 connections back together and turn the heater on (to
the right) and the heater should be back in operation and the
water valve to its full open position.
9. Make sure inlet water is on, gas is on, and power is on and run a
hot water tap and the heater should be operating
fi
ne now.
10. If the problem persists, please contact Bosch technical support
at 800-642-3111 for further assistance.
