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Operation and Maintenance
Envistar Top 04-21
DSET.190501.01.EN
Continuous product development may give rise to specification changes without notice.
6.6 Air Heater electric (Code ETAB-EV, ETKB-EV, ETAB-SV)
• ETAB-EV for unit assembly
• ETAB-SV for unit assembly reversible heat pump
• ETKB-EV for duct mounting
Air heater electric (ETAB-EV, ETAB-SV)
Air heater electric size 04-12 (ETKB-EV)
The heating coil consists of “unsheathed” electric heating rods. A substantial
accumulation of dust or other impurities on the heating rods will cause them to
overheat. This could shorten their service life. This might also entail an odour of
burnt dust and, in the worse case, the risk of fire. Overheated electric heating
rods may become deformed or loosen from their suspension fasteners and heat
the air unevenly.
Inspection
Check that the electric heating rods are correctly positioned and that they are
not deformed in any way.
Cleaning
Vacuum and/or wipe all surfaces with a cloth.
Function
1. Simulate reduced required output by temporarily lowering the temperature
setting (setpoint), so that all the electric output steps (contactors) switch out.
2. Then sharply increase the setpoint setting and check that the electric output
steps switch in.
3. Restore the temperature setting.
4. Stop the air handling unit (NB: Do not break the circuit with the safety
switch). All the electric output steps should switch out (i.e. the contactors in
the OFF position). Stopping the unit may be delayed approx. 2–5 minutes to
allow the fans to cool the heat energy stored in the air heater.
The electric heater is equipped with dual temperature limiters. The one that re-
sets itself automatically should be set to 70°C.
The overheat protection with manual reset interrupts operation when the heater
reaches approx. 120°C and is located on the cover panel on the side of the
heater.
Determine the cause of overheating and take corrective action be-
fore you reset the protection device.
Please note that the risk of overheating increases as the air flow through the unit
decreases. The air speed should not be lower than 1.5 m/s.