Page 40
9.9 Heater element replacement
Removal
»
Remove and open steam cylinder as
described in the „Removing and
cleaning the steam cylinder“ section
(section 9.4).
»
Open cylinder clamping belt (6) and
lift-off cover (7) with heater elements
(8).
»
Separate thermo switch capillary
tube from heater element(s) by deta-
ching the retainer clips.
»
Remove wiring of the heater ele-
ment(s) in question from connector
terminals (mark positions for reclam-
ping).
»
Unscrew heater element fixing
nut(s) from cylinder cover.
»
Pull heater element/s downward out
of steam cylinder cover.
»
Remove grounding ring cable lug.
»
Clean the sealing surface on the
underside of the cover around the
area where the new heater element
will be installed.
Reinstallation
»
Install replacement heater ele-
ment(s) (with new sealing) while
considering the correct sequence of
all of the mounting parts. Ensure
proper grounding and tighten nut(s).
»
Insert heater element wires into the
terminals of the wiring connector fol-
lowing the markings made when dis-
sembling. Polarity is not an issue.
»
Refit thermo switch capillary tube to
heater element(s) using retainer
clips.
»
Reassemble steam cylinder and
reinstall in humidifier housing as
described in the „Removing and
cleaning the steam cylinder“ section.
9.10 Releasing the thermical
safety devices
9.10.1 Variety of thermal protection
devices in use
For overheat protection, the steam humidifier
is equipped with one or two thermo switches,
depending on the power output rating. They
are mounted on the steam cylinder cover.
The thermo switch/es is/are coupled to the
heater element/s by means of a capillary
tube. Each of thermo switch controls 1 to 3
heater elements. Thus, with 6 heater element
units, each one of the thermo switches is
assigned to a group of 3 heater elements.
For additional safety in case of one of the
thermo switches beeing defective, a Klixon
thermo switch is screwed to the cylinder
cover.
The mounting positions of a single thermo
switch and the Klixon are shown in the next
section in an exemplary representation.
Supplementary to the thermal protection
devices in conjunction with the steam cylin-
der, the solid state relay/s is/are protected by
bimetal switches to avoid damage introduced
by inadequate ventilation due to e.g. vent
holes that are obstructed.
From an electrical point of view, the thermo
switch/es on the cylinder cover, the bimetal
switch/es on the soid state relay/s as well as
the Klixon thermo switch mounted on the cyl-
inder cover are all wired in series. If one of
the devices mentioned triggers due to an
overheat situaton, the main contactor K1
switches off and controls enters the „120“
error state (i.e. „Thermo switch“). Steam pro-
duction is then interrupted. A unit restart is
required which is, however, only possible
after the bimetal switch/es has/have cooled
down and/or the thermo switch/es and/or the
Klixon thermo switch (see sections 9.10.2
and 9.10.3) were unlocked.
