ahu maintenance

8/6/2019 AHU Maintenance

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STING Compact Air Handling UnitMaintenance Instructions

September 2007


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Safety precautions

WARNINGAny open air inlet or outlet unit connec-tions must be fitted with a protectivescreen before the air handling unit iscommissioned.

All the electrotechnical and mechanicalsafety devices must also be installed

before the air handling unit can becommissioned

Before carrying out any work in the air handlingunit, make sure that the power supply to the unithas been isolated. Note that the electric airheater, if installed, has a separate power supplythat isnt isolated across the main switch of theair handling unit.

Take great care when opening the venting

connections for hot water to the air heater. Thereis risk of water hammer or escaping steam.

Switch off the main switch of the air handlingunit before you open the inspection doors tocarry out service work or an inspection. All thesafety devices shall be refitted at their properlocations before you restart the unit.

Open space (backing distance) must be provid-ed in front of the electric air heater and electricequipment cubicle in accordance with local elec-trical safety regulations. Use the control termi-

nal display when stopping the air handling unit.

The inspection doors of the air handling unit areequipped with lockable handles. See to it thatthe air handling unit inspection doors arelocked before you leave the unit and keep thekeys inaccessible to unauthorised personnel

The inspection doors of filter/fan sections mustnot be opened while the air handling unit isoperating. The fans generate considerable pres-sure above atmospheric on the doors.

Service intervalsThe service schedule lists the service work necessary forthe unit sections that may be included in the airhandling unit. The unit contains one or more of theseunit sections. Delete from the service schedule the unitsections, which are not included in your particular unit.The date and the initials of the person carrying out thework should be entered on every service occasion.The intervals between service are based on the assump-tion that the unit is in operation for about 2000 hours per12-month period in a normal comfort installation.If the supply or extract air has a high dust content, theunit should be serviced more frequently.

Safety precautions General maintenance instructions

Flkt Woods 4718 GB 07.10 2 Specifications are subject to alteration without notice

STING Air Handling Unit MAINTENANCE


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Service schedule



Applies from 20 .. .. .. t. o. m. 20 .. .. ..

Symbol Service work Date Service work Date Service work Date

Initials Initials Initials

3-monthly / 9-monthly service 6-monthly service 12-monthly service

Filter

Rotary

heat

exchanger

Fan

Casing

Check the pressure

drop and change the

filter, if necessary.

Carry out a visual

inspection. Check the

sealing strips.

Carry out visual

inspection

Carry out visual

inspection

Check the sealing

strips in the doors.

Clean the interior, if

needed.

Clean the impeller, fan

casing and unit

casing. Check the

bearings.

Check the pressure

drop and change the


Clean the rotor

Check the pressure

drop and change the


Clean the rotor.

Check the monitoring

and purging equip-

ment

3

9

3

9

3

9

Symbol Service work Date Service work Date Service work Date

Initials Initials Initials.

3-monthly / 9-monthly service 6-monthly service 12-monthly service

3

9

3

9

Damper Check the damper

performance.

Check the damper

performance.

Clean the damper.

Check the damper

performance.

Air heater

Air cooler

Carry out visual

inspection

Clean the finned coil

body and electric

heating rods.

Clean the finned coil

body, electric heating

rods, drip tray andcasing


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Changing the sealing strip in the inspectiondoorThe sealing strip for the inspection doors is available asa spare part and, if required, must be changed to ensurethat the unit is tight.

Spare partsThe spare parts and accessories for this air handling unitshould be ordered from your nearest Flkt Woods ABrepresentative.When ordering spares, specify the product codes listedin the Spare Parts Catalogue

To remove individual panels

To dismantle the inspection doorsThe doors can easily be dismantled by pulling out thepins, Item 3 in Fig. 3.

To adjust the hingesRelease the hinge items 1 and 2, and adjustthe gaps "A" so that they will be equallywide. Gap "B" should be max. 3 mm. Use aspacer of suitable thickness. Push Items 1and 2 together and tighten the screws. Ifthreads have been damaged, a

blind rivet nut can be usedto secure the screw. Checkthat the sealing stripsaround the inspection doorseal tightly, and that thedoor is easy to open andclose. Also check the opera-tion of the lock.

General maintenance instructions



Fig. 1

Screw

Plug

Screw

Screw

To dismantle the Handle

Handle

Screw

Bult

Rose

Locking tongueNut

Plastic washer

Lock with key

Fig. 2

Fig. 4. Horizontal unit.

Fig. 3

A

A

B = max. 3 mm

2

1

2

3

1

12


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FilterAs dust is gradually collected in the filter, the flowresistance of the filter will increase accordingly and thiswill cause a reduction in the air flow. The filter musttherefore be changed regularly, at intervals determined

by the dust concentration in the air.

The maximum permissible pressure drop increase forthe class F7 (EU 7) filters supplied with the STING airhandling units is 100 Pa.

Indication of when the filter should be changed can beprovided by the ETAZ-31 manometer or by an electric

impulse from the STYZ-28 filter monitor, for example.The manometer scale should preferably be providedwith a red marking at the final pressure drop at whichchanging of the filter is recommended.Aset of replacement filters should be available for everyinstallation. Replacement filters and spare parts can beordered from your nearest Flkt Woods representative.

Fitting new filters, sizes 10-35.

When fitting the filter cassettes, make sure that theirrear edge is properly seated in the sealing rail.Insert the filter as indicated by the arrow

Fitting new ultra compact filter, STING Topsizes 20-35.

Fitting new bag filters, sizes 40-85.

Press in the lever, 1, of the off-centre locking mechanism,2, to release the filter cassette. Withdraw the fouled filter.Wipe the surfaces inside the filter space clean. Checkthat the rubber sealing strips, 3, are undamaged beforeyou fit new filters. No sealing strip is necessary betweenthe cassettes. Carefully insert the new filter cassettes soas not to damage the filter bags.

Filter size

General maintenance instructions



Fig. 6

Fig. 5 1)

2)

3)

1)

Size Number of filter inserts Length of the

filter inserts

10 One 592 + 287 mm 300

20 One 392 x 792 360

30, 35 One 892 x 490 547 (360)*

40 Two 592 x 592 547

50 Two 592 x 592 + One 387 x 592 547

65 Three 592 x 592 + Three 287 x 592 547

80, 85 Eight 592 x 592 547

* The filter of an AHU with an air inlet on top is shorter than the filter of

an AHU with an end connection frame inlet.

Fig. 7Place the filter cassettes in the

rails.


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Supply air fan, right-hand unit/lower level:The rotor rotates downward.Applicable to sizes:1085 2085

Supply air fan, left-hand unit/upper level:The rotor shall rotate upward.Applicable to sizes:1085 2085 2035

Supply air fan, left-hand unit/lower level:The rotor shall rotate downwardApplicable to sizes 2085.

Supply air fan, right-hand unit/upper level:

The rotor shall rotate upward.Applicable to sizes:1085 2085 2035

Supply air fan, right-hand verticalunit/upperlevel:The rotor shall rotate right-hand.Applicable to sizes 1020.

Supply air fan, left-hand vertical unit/lower level:The rotor shall rotate left-hand.Applicable to sizes1020.

Rotary heat exchanger

The rotary heat exchanger is extremely important forthe performance and economy of the air handlingunit. It is therefore important to keep it clean and inproper working order.The rotor is normally self-cleaning due to the continu-ously reversing airflow through the rotor as it passesinto and out of the intermediate plane.The rotor is also equipped with a purging sector thatprevents the extract air from being carried over to thesupply air as the rotor rotates.It is important for the purging operation that the airpressure in the extract air section is lower (higher sub-atmospheric pressure) than the air pressure in thesupply air section. There should be 0-20 Pa greatersub-atmospheric pressure on the extract air side. Thisdirects the air leakage and the purging air flow towardthe extract air and extract air transfer to the supply aircan be avoided. Throttling plates located upstream ofthe extract air filter are utilised for adjusting the pres-sure differential between the upper and lower levelsinside the unit.The direction of rotation of the heat exchanger rotormust also be correct in relation to the location of thesupply air fan in the STING air handling unit.





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The performance of the rotor drive motor should bechecked at least once every 6 months. The drive trans-mission has been lubricated to last throughout itsuseful life.The rotor shaft bearings are permanently lubricated.Therefore, no subsequent lubrication is necessary.Check that to make sure that the drive belt isnt slip-ping or that it hasnt slipped off the rotor or pulley.

Face surfacesCheck that the rotor surfaces are not coated with dust.If necessary, clean by vacuum-cleaning or blowing

with compressed air from the clean side towards thedust-coated side. If vacuum-cleaning or blowing withcompressed air proves inadequate, (if the dust isgreasy), clean the rotor surfaces as follows:Spray a degreasing agent [products marked with aSWAN or BRA MILJVAL (Good Eco-Choice) arerecommended] by hand onto the dust coated-surfaceof the rotor, and then blow clean with compressed airfrom the opposite side.As an alternative, the rotor can be cleaned with low-pressure steam or flushed with water if facilities areavailable for collecting the water. When using a high-pressure nozzle to clean the rotor, the jet of water must

be aimed at right angles to the rotor structure. Thespray nozzle should preferably be held approx.50 mm from the rotor surface. Suitable pressure: upto 80 bar.

Sealing stripThe rotary heat exchanger is equipped with a sealingstrip around its periphery and against its intermediateplane for minimising air leakage between the supplyair and the extract air sides. Check to make sure thatthe sealing strip is not damaged along its entire length.Replace if necessary.

To change the drive beltDue to wear, it may be necessary to change the drive

belt.

The original belt has a welded joint. The replacementbelt is jointed together by means of the pin suppliedwith it. Make sure that the belt has the correct lengthaccording to the table below.




Caution! Never use acetone or othersimilarly aggressive liquids

Size Lenght, mm

10 2036

20 2720

30, 35 3222

40 3928

50 4880

65 5660

80, 85 7540


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FWG-Sting-G

B2007.0

9-4

718

Copyright2006FlktWoodsGroupCondesignInfocomAB+4

636308380

Flkt Woods AB, SE-551 84 Jnkping, Sweden

t+46 (0)36-19 30 00f +46 (0)36-19 36 20

w www.flaktwoods.com

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