Servicing and maintenance of Kesair air-handling units

Keep your top-quality Kesair units in perfect condition by ensuring correct installation and their regular appropriate maintenance.

GENERAL INFORMATION ON MAINTENANCE

Regular inspection and maintenance of an air-conditioning system ensures the correct and economical operation of the units. Insufficient ventilation interferes with the normal functioning of the building’s structures and can lead to problems with indoor air quality – and even to prohibition of use of the building. Lack of ventilation or the system’s incorrect operation can damage the building’s structures.

Inspection and maintenance of the system always requires professional competence and experience in the operation of air-conditioning and automation systems. The inspection and maintenance procedures are performed twice a year; at the beginning and at the end of the heating season. Regular servicing and maintenance ensure that the units operate as designed and have a long service life.

THE OPERATION AND MAINTENANCE PLAN

The operation times and adjustments for an air-conditioning system are determined in accordance with the needs of the building’s users. The system’s operation plan is usually prepared early on, in the design phase of the building and its ventilation system. This plan presents the operation times and coverage areas of the various components of the air-conditioning system. Often, the operation plan takes the form of device-specific functional diagrams and descriptions. The operation plan forms the starting point for devising a maintenance plan. For the purpose of maintenance, the maintenance personnel must have instructions at their disposal with detailed specification of the procedures to be performed for the various devices. The instructions should be attached to the calendar. The procedures are compiled in the form of a table in which the annual servicing times for the devices are readily visible.

DEVICE AND MAINTENANCE CARDS

Kesair supply-air units are delivered with a pre-completed device card, which provides all the service-relevant data, such as the filtering classes of filters, fan specifications, and electrical values. All servicing and maintenance procedures performed on a device, with dates and acknowledgements, are marked on the maintenance card.

SERVICE INSTRUCTIONS

For the duration of servicing procedures for a supply-air unit, the unit must be stopped, and unintentional restarting during servicing must be prevented (e.g., via a safety switch). Special attention must be paid to opening and closing the hatches, so that the seals do not become damaged and unit tightness is not compromised. During servicing work, the various device parts and the fresh-air chamber are carefully vacuum-cleaned.

Louvred dampers

A louvred damper is placed in the fresh-air duct before the heater, and in the exhaust-air duct after the extraction fan. The dampers that are in contact with outdoor air are usually thermally insulated. A louvred damper is also used in the mixing-shunt section, in frost-prevention for the heat-exchanger plate, and in arrangement of the bypass function (summer mode). The purpose of a louvred damper is to restrict, prevent, and guide air flow in accordance with the required operation. This damper type consists of a frame and interconnected, sealed metal louvres, which turn in opposite directions. The louvred damper operates with a damper motor attached to a shaft. For the functioning of the louvred damper, the most crucial factors are the mobility of the louvres, the condition of the seals, and the operation of the damper motor.

Maintenance procedures (routine maintenance)

  • Clean the louvres and the seals
  • Check the condition of the louvres, seals, and bearings
  • Do not lubricate the plastic bearings of the shafts
  • Check the mobility of the louvres from one end of their complete travel to the other
  • Check the connections between the actuators and the shafts
  • Check that the damper closes properly when the unit is stopped (dampers in contact with outdoor air)
  • If the unit has an air-circulation damper, it should usually open when the unit is stopped

Maintenance procedures (function testing and troubleshooting)

The inspection must be performed by a professional who is familiar with the unit’s automation.

  • Check that the louvred dampers function correctly when one starts and stops the unit
  • Check that the louvred dampers operate in accordance with the adjustment diagram
  • Check that the louvred dampers operate correctly in cases of disturbance: frost-protection, fire-protection, and prevention of frosting up

We reserve the right to make changes without prior notification.

Air filters

Air filters are installed in the fresh-air duct before the heater, and in the exhaust-air duct before the heat-recovery unit. The purpose of these filters is to keep the heaters, heat-recovery units, fans, and ventilation ducts clean. When impurities in the air accumulate, they prevent correct and appropriate operation of the device components. Replacing the filters is a central maintenance procedure for an air-conditioning unit. When a filter becomes dirty, the pressure loss increases and the air flow decreases. When the pressure difference increases to its pre-set maximum value, the filter must be replaced. Ensure that used filters are not left in the machinery room and that there is always a complete set of spare filters available for every air-conditioning unit, for the next filter replacement.

Maintenance procedures (routine maintenance)

  • Before starting to replace the filters, make sure that you have a complete replacement-filter set available
  • Use a respirator mask when replacing the filters
  • Detach the dirty filters, and place them directly into a waste bag, closing the bag tightly
  • Vacuum-clean the filter frame and the filter element
  • Place the new filters in position, and check that they are seated correctly
  • Order a new set of replacement filters, and deliver the dirty filters to a waste-disposal sit

Maintenance procedures (function inspection and troubleshooting)

The inspection must be performed by a professional who is familiar with the unit’s automation.

  • • Test the operation of the filter guard and the issuing of the alert

Heaters, electric

An electric plate heater is placed at the pressure side of the fan. The heater is constructed of tubular resistance heaters, which do not require any specific maintenance. The heater has integrated protection against overheating; the heater requires manual resetting after this is triggered. There is an optional fire-protection thermostat in the supply duct and a time relay controlling the after-run of the automatics.
Triggering of the overheating protection or of the fire-protection thermostat is always a sign of malfunction in the system. The disturbance should be cleared before the air-handling unit is restarted.

Maintenance procedures (routine maintenance)

  • If the unit is equipped with an electric fin heater, vacuum the fin surfaces

Maintenance procedures (function inspection and troubleshooting)

The inspection must be performed by a professional who is familiar with the unit’s automation.

  • Check the operation of the overheating protection and the fire-protection thermostat, along with the set values for these
  • Check the operation of the after-run relay and the value set for it
  • Check the operation of the adjustment steps of the heating resistors
  • Check the constancy of the adjustment and that the value set for it is correct

Only a skilled professional is to replace a burnt-out heating resistor.

  • Detach the resistor fuses
  • Check the wiring connections of the resistors
  • Measure the resistor values, one at a time, in order to detect any discontinuity
  • Order a new replacement resistor, replace the damaged resistor, and reconnect the wiring
  • Close the service switch, and start the unit
  • Test the operation of the heating and the safety device

Heaters, water-circulation

The water-circulation heater is on the intake side of the fan, and the after-heater is placed on the pressure side. The heater is made from copper piping and aluminium fins. A heater installed in the fresh-air duct is always equipped with an ice-protection thermostat. The triggering of that thermostat is always a sign of a malfunction in the system. The disturbance should be cleared before the air-handling unit is restarted.

We reserve the right to make changes without prior notification.

Maintenance procedures (routine maintenance)

  • Clean the heater fins with a vacuum cleaner or compressed air
  • Check that there is no air in the heater
  • Check that the water-circulation pump is switched on
  • Check the condition of the thermostats, piping, and insulation
  • Check the temperature of both the water flowing to the heater and that returning from the heater

Maintenance procedures (function testing and troubleshooting)

The inspection must be performed by a professional who is familiar with the unit’s automation.

  • Check the operation of the ice-protection thermostat
  • Check the operation of the heating adjustment valve
  • Check the constancy of the adjustment and that the value set for it is correct
  • Check the operation and the value set for the return-water thermostat (with the unit not switched on)
  • Check the alarm function of the water-circulation pump

Fans, direct-drive

In air-handling units with a direct-drive fan, maintenance procedures are focused on cleaning. In particular, the cleanness of the propeller wheel must be ensured. Dirt adhering to the propeller wheel will create an imbalance in the wheel, which leads to faster wearing of the fan bearings.

Maintenance procedures (routine maintenance)

  • Before stopping the unit, listen to the fan sounds at all rotation speeds
  • Stop the air-handling unit, and prevent its restarting
  • Clean the propeller wheel by vacuuming (take special care not to move or detach the weights that were attached to the fan propeller wheel during balancing)
  • Check the fan visually
  • Listen to the sounds during starting

Maintenance procedures (function inspection and troubleshooting)

The inspection must be performed by a professional who is familiar with the unit’s automation.

  • Check that the fan operates at the speed indicated, and monitor the control operation for correct operation
  • Check that the fan’s operation times are correct
  • Check the issuing of the alarms (for protection against overheating and operating data)
  • Check the operation of the flow monitor

Fans, V-belt drive

In air-handling units equipped with a V-belt-driven fan, maintenance is focused on cleaning and on monitoring the condition of the motor, fan, and V-belt drive. Special attention must be paid to the tightness and condition of the V-belt, for ensuring correct operation.

Maintenance procedures (routine maintenance)

  • Before stopping the unit, listen to the fan sounds at all rotation speeds
  • Stop the air-handling unit, and prevent its restarting
  • Clean the propeller wheel and hood by vacuuming (take special care not to move or detach the weights that were attached to the fan propeller wheel during balancing)
  • Visually inspect the condition of the motor, fan, and V-belt drive
  • Check the vibration dampers in the installation base of the fan and motor
  • Check the flexible connectors of the fan
  • Check the condition, tightness, and alignment of the V-belt (refer to the instructions below)
  • If the belts are worn, replace them (the unit delivery includes spare belts)
  • After you have replaced the belts, order new ones
  • Listen to the sounds during starting

We reserve the right to make changes without prior notification.

Determining the V-belt tightness

  1. Check the device card for information on the V-belt drive
  2. Measure the length of the belt span (the free length of the belt), referring to the illustration below).
  3. Measure the perpendicular bending force, which should cause a 16-mm deflection per metre of belt span.
  4. Compare the force measured with the figures in the table below. When the force measurement is below the range indicated, the belts are slack. A new drive should be tightened to the upper end of the range indicated, because the belts stretch during the ‘breaking-in phase’.

Force required to deflect the belt 16 mm per metre of belt span

Belt profile Diameter of smallest wheel, mm Newtons, N Kiloponds, kp
SPZ 67-95
100-140
10-15
15-20
1,0-1,5
1,5-2,0
SPA 100-132
140-200
20-27
28-35
2,0-2,7
2,8-3,5
SPB 160-224
236-315
35-50
50-65
3,5-5,1
5,1-6,6
SPC 224-355
375-560
60-90
90-120
6,1-9,2
9,2-12,2

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The tightness of the drive belt must be checked when the unit has been in operation for approx. 30 minutes.

Alignment of the belts

For the belts to have a long service life, it is important that the motor and fan shafts be parallel and that the belt pulleys be exactly in line.

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Maintenance procedures (function inspection and troubleshooting)

The inspection must be performed by a professional who is familiar with the unit’s automation.

  • Check that the fan operates at the speed indicated, and monitor the control operation for correct operation
  • Check that the fan’s operation times are correct
  • Check the issuing of the alarms (for protection against overheating and operating data)
  • Check the operation of the flow monitor

Heat exchangers, cube

The maintenance of a plate heat exchanger includes cleaning the exchanger fins and checking the front-surface dampers or bypass dampers and the actuator.

Maintenance procedures (routine maintenance)

  • Check the condition of the front-surface and bypass dampers and the fastening of the damper motors
  • Check that the heat-exchanger surfaces are clean

Cleaning the cube

  • Use a vacuum cleaner, compressed air, a water hose, a stirrup pump, or a watering can
  • If you clean the cube with water, protect the damper motors by covering them with plastic
  • Then, use a water hose and a mist shower to clean the fin gaps from both the supply and the exhaust side
  • If washing with a cleaning solution, use a mild detergent
  • Monitor the discharge of water from the condensation-water basin and the operation of the water seal
  • Allow the condensation-water basin to empty completely
  • Remove the protective plastic covers, close the service hatches, and start the unit

NOTE: Prevent water from splashing onto the motors, filters, and seals.

Maintenance procedures (function inspection and troubleshooting)

The inspection must be performed by a professional who is familiar with the unit’s automation.

  • Check the pressure difference in the heat exchanger from the supply and exhaust side both
  • Check the efficiency of the heat exchanger (the temperature difference)
  • Inspect the automatics of the heat-recovery unit (adjustment and defrosting)

Heat exchangers, rotary

The maintenance of the rotary heat exchanger includes cleaning of the fluted fins of the rotor component and checking of the condition of the drive motor and the belt.

Maintenance procedures (routine maintenance)

  • Check the condition and tightness of the drive belt
  • Check the seal between the rotor and the casing
  • Check that the heat-exchanger surfaces are clean

Cleaning the rotor

– Clean the fin gaps, using a vacuum cleaner or compressed air

Maintenance procedures (function inspection and troubleshooting)

The inspection must be performed by a professional who is familiar with the unit’s automation. – Check the pressure difference in the heat exchanger, separately from both the supply and the exhaust side – Check the efficiency of the heat exchanger (the temperature difference) – Inspect the automatics of the heat-recovery unit (adjustment and defrosting)

Heat exchangers, heat-recovery heater

The structure of the heat-recovery heaters is equivalent to that of a water-circulation heater except that beneath a heater that recovers heat, there is always a condensation-water basin into which the water that has condensed on the fin surfaces flows. From this basin, the condensation water gets directed to the sewer via the water seal.

We reserve the right to make changes without prior notification.

Maintenance procedures (routine maintenance)

  • Clean the fins of the heat-recovery heaters, using a vacuum cleaner
  • Clean the condensation-water basin, and check the cleanness of the water seal and water outlet
  • Check the frost-resistance of the heat-exchanger fluid
  • Check the pressure and the relief valve of the fluid system
  • Check the operation of the expansion tank (the pre-pressure)
  • Vent the heaters
  • Check that the water-circulation pump is switched on
  • Check the temperature in the supply and return pipes
  • Check the operation of the regulating valve

Maintenance procedures (function inspection and troubleshooting)

The inspection must be performed by a professional who is familiar with the unit’s automation.

  • Check the efficiency of the heat-recovery heaters (the temperature difference)
  • Inspect the automatics of the heat-recovery heaters (adjustment and defrosting)

Cooling radiators, coolant-based

The structure of the cooling radiator is similar to that of a heater, but a cooling radiator always has a condensation-water basin under it in which the water that has condensed on the fin surfaces will be collected. From this basin, the condensation water gets directed to the sewer via the water seal.

Maintenance procedures (routine maintenance)

  • Clean the fins of the cooling radiator, using a vacuum cleaner
  • Clean the condensation-water basin, and check the cleanness of the water seal and water outlet
  • Check the fluid volume in the coolant-water system and the operation of the relief valve
  • Check the operation of the expansion tank (the pre-pressure)
  • Vent the cooling radiator
  • Check that the water-circulation pump is switched on
  • Check the temperature in the supply and return pipes
  • Check the operation of the regulating valve
  • Check the operation of the water-cooler and the amount of coolant
  • Clean the condenser

Maintenance procedures (function inspection and troubleshooting)

The inspection must be performed by a professional who is familiar with the unit’s automation.

  • Test the water-cooler’s automatics and the values set for it
  • Check the temperature of the cooling-water tank
  • Test the automatics of the cooling radiator and the values set for it

Cooling radiators, refrigerant-based

The cooling radiator operates on the principle of transfer of the heat from evaporation of the refrigerant in the radiator. Evaporation heat is passed into the outdoor air via the compressor and the condenser. The radiator is a finned radiator equipped with a condensation-water basin.

Maintenance procedures (routine maintenance)

  • Clean the fins of the cooling radiator, using a vacuum cleaner
  • Clean the condensation-water basin, and check the cleanness of the water seal and water outlet
  • Check that the cooling compressor runs and operates appropriately
  • From the sight glass, check that there is enough refrigerant in the pipe system
  • Clean the condenser

Maintenance procedures (function inspection and troubleshooting)

The inspection must be performed by a professional who is familiar with the unit’s automation.

  • Check the automatics of the cooling apparatus and the values set for it
  • Check the automatics of the cooling radiator and the values set for it

We reserve the right to make changes without prior notification.

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