systemair 45
3.7 Heating and cooling coils
Caution
See also section 3.1 General instructions.
We suggest that the piping is made in such a way that in the case of maintenance or replacement of the
register, emptying the system and dismantling the piping is as easy as possible.
Filling of water piping:
• Partially open the transfer medium supply valve and wait for the blade register to uniformly warm up / cool down.
• Fully open the transfer medium supply valve.
• Vent the system.
• Start the fan.
Draining of water piping:
• Close the transfer medium supply valve.
• Slowly open the draining valve until the pressure is released from the heat exchanger, then fully open the draining
valve and the venting valve.
3.7.1 Frost protection
The protection of the heating coil against freezing is always carried out with a contact temperature sensor mounted on
thereturnpipeoftheheatinguidandwithautomaticregulation.Thecontactsensormustbesetto14°C.
As an option, a capillary thermostat with a capillary mounted in a frame over the entire cross-section of the air
conditioner can be installed. The thermostat must be set to 5°C.
As the temperature drops below the set value, the thermostat and automatic control system must carry out the
following operations:
• Stop the fan,
• closetheoutdoorairintakecontroldamper,
• fully open the heating medium valve and
• start the circulation pump.
Caution
In the case of air handling units that include a cooling coil, preheater and reheater, anti-frost protection at
thepreheaterissufcient.
In the event of a prolonged interruption of the power supply (or unit shut-down) or an interruption of the
heating medium supply, drain the heating coil to prevent it from freezing. In order to absolutely prevent
theriskoffreezing,drythetubebankbyblowingitwithcompressedairafterdraining.
If the automatic control of the air handling unit is supplied by Systemair, the anti-frost protection is
integratedintheunitinthefactory;ifthecontrolsystemisimplementedbythecustomeroranother
installer, arrangements for heating coil anti-frost protection are obligatory.
Thetype,connection,operationandmaintenanceofthecapillarythermostatarespeciedinthe
operating instructions for the electrical control cabinet, regardless of whether the air conditioning control
is manufactured by Systemair, or determined and manufactured by the customer.
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