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Operation and Maintenance
Envistar Top 04-21
DSET.220501.07.en
Continuous product development may give rise to specification changes without notice.
6.5 Counter-flow exchanger (code TXMM)
The purpose of the counter-flow exchanger is to recover heat
from the extract air and transfer this heat to the supply air in
order to minimise energy use.
Faults in counter-flow exchanger functionality reduce recovery
efficiency and increase energy consumption. The projected
supply air temperature will not be reached when outdoor tem-
peratures are low.
Possible reasons for reduced recovery efficiency could be the
fouling of the heat-exchanging surfaces (fins) or that the by-
pass damper is not closing completely.
A reduction of the extract air flow, e.g. due to fouling of the
extract air filter, entails reduced heat recovery efficiency.
Inspection
WARNING!
Risk of serious personal injury and/or damage to air handling
unit.
Read and understand the entire chapter "1.5 General safety
messages" before working on, servicing, or inspecting the air
handling unit.
1. Shut down the unit via the service switch in the control equipment, safety
switch in the 0 position.
2. Wait until the fans have stopped, then open the inspection door.
3. Inspect the fins for fouling.
4. Perform a visual inspection of the automatic defrosting dampers and dam-
per motors.
5. Check that the bypass damper is tightly shut when defrosting is not taking
place.
6. Check the waste oulet and water trap function. A water trap without a non-
return value should be filled with water.
