OM-DHS 17
Maintenance
2. Jacket Vacuum/Removing Air from Jacket
When the kettle is cold, a positive pressure reading on the pressure/vacuum
gauge or a reading near 0 indicates that there is air in the jacket. Air in the
jacket acts as an insulator, and slows kettle heating.
To remove air:
a. Start the unit. (Be sure there is water or product in the kettle when heat-
ing).
b. When the pressure/vacuum gauge reaches a positive pressure reading
of 5 PSI, release the trapped air and steam by pulling up the safety valve
ring for about 5 seconds. Repeat this step three or four times. Then let
the pull ring snap back into the closed position.
c. If there is little discharge (mostly air), and the pressure gauge drops back
to 0 PSI, allow the pressure to build back to 5 PSI and repeat the proce-
dure.
d. Once steam has been vented from the jacket as described in b, above,
remove the hot water from the kettle and replace it with cold. This will
condense steam in the kettle jacket, and the pressure gauge should
show a reading of 20 to 30 inches mercury (Hg) below 0. If it does not, or
if the vacuum is leaking down, contact a Groen authorized service agency
to correct the problem.
3. Jacket Filling and Water Treatment
The jacket was charged at the factory with the proper amount of treated water.
You may need to restore this water, either because it was lost as venting
steam or by draining. If you are replacing water lost as steam, use distilled
water. If you are replacing treated water that ran out of the jacket, prepare
more treated water as directed in “Water Treatment Procedure,” below.
a. Allow the kettle to cool completely. The procedure will be easier with the
kettle under vacuum ( pressure gauge reading below 0).
b. Remove the pipe plug from the jacket fill assembly. Pour in the distilled or
treated water. Using a funnel will help you in this process. Hold the pres-
sure relief valve open while you pour, to let air escape from the jacket.
Continue adding water until the water level rises to the center of the
round sight glass.
c. Position a funnel in the opening and fill it with properly treated water.
d. Air that gets into the jacket during the filling operation must be removed,
because it will make heating less efficient. Follow the procedure in
Jacket Vacuum/Removing Air From Jacket above, to restore a negative
pressure reading.
Safety Valve
Pressure Gauge
Test the safety valve at least twice monthly
Check Valve
Pipe Plug
