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NH-4 Fluid Heaters
17
Part 1602369-03
E
2020 Nordson Corporation
Repair
WARNING: Allow only qualified personnel to perform the following tasks.
Follow the safety instructions in this document and all other related
documentation.
WARNING: Remove power, relieve fluid and air pressure, and allow the
heater to cool down before performing any repairs. Failure to observe this
warning may cause serious injury to personnel and/or damage to
equipment.
Thermostat Replacement
When a thermostat fails in the on position, it causes the heat to rise above
the preset limit. The heat limiter senses the excess heat and opens the
electrical circuit to the heating cartridge. This prevents damage to the
heater, however, it does require replacement of the heat limiter. If either the
thermostat or the heat limiter has failed, always replace both.
Thermostat Removal
WARNING: Make sure no spray activity is in progress while the cover is
removed from the electrical enclosure. Failure to observe this warning may
cause serious injury to personnel and/or damage to equipment.
NOTE: Thermostats are coated with heat-conductive paste before
installation. The viscosity of this paste may make removal difficult. It may
be easier to remove the thermostat while the heater body is still warm.
See Figure 8.
1. Remove the six socket head screws (1) and six lock washers (2)
securing the cover (3) to the electrical enclosure (4).
2. Disconnect electrical lead 1 from the COMMON terminal on the
thermostat (5).
3. Disconnect electrical lead 2 from the NORM CLOSED terminal on the
thermostat.
4. Remove the screws (7) and lock washers (6) securing the thermostat (5)
to the electrical enclosure (4). Carefully remove the thermostat from the
heater.
Thermostat Installation
1. See Figure 8. Insert the heat conductive paste applicator (supplied with
the thermostat kit) into the fluid passage body bore stamped T (4) and
dispense all the paste into the bore.
2. Using a screw and lock washer, install the thermostat bracket support
into the electrical enclosure and tighten securely.