Air Conditioning Systems [Maintenance of]

Descriptions

Contract requirementsAll maintenance and repairs will be carried out in accordance with the original equipment manufacturers recommendations. Replacement consumables and parts must be supplied and fitted in accord with original manufacturer specifications. Refurbished parts are not acceptable unless approved by the customer.All services, parts and consumables supplied against this agreement shall comply with relevant legislation, British Standards, Department of Health policy guidelines and Health and Safety requirements.Provisions of all materials, equipment, access to approve spare parts and provision of suitably trained personnel, who shall be regularly updated on new equipment requirements necessary to ensure maintenance is carried out to the manufacturers recommended specification, is the sole responsibility of the supplier.The equipment covered by this contract will be unique to the site at which it is located and the contract requirement, range, age and amount of equipment located at each site, will vary.Periodic servicing and inspectionPreambleWork must only be performed by competent persons. The following refer briefly to more common requirements; the list is not intended to be complete.Fix a warning notice at each plant room entrance indicating that maintenance work is being undertaken.When working on electrical equipment, control panels, fix barrier warning tape sectioning off the area against unauthorised entry.Before working on electrical equipment, a ‘permit to work’ signed by an authorised NHS Estate Officer must be obtained.Equipment must be disconnected from the power supply by operating the switch or starter and also the isolator and locking off; as a further precaution an authorised NHS Estate Officer may withdraw supply fuses.When inspecting rotating equipment whilst it is moving or subject to automatic start be especially careful of ‘nip-points’ such as belts and pulleys.Do not ‘short out’ control safety circuits with wire hooked onto the terminals or by temporary shorting bridge or by any other method including disabling computer control without first obtaining a permit from an authorised NHS Estate Officer.Use only hand and small power tools suitable for and operated from an 110v electrical supply or are battery operated.Never carry out work where there is any element of danger if it is reasonably practical to eliminate that risk.Ensure safe working conditions, to give adequate protection and safe access where necessary, proper scaffolds, guard rails, toe boards, etc and ladders, must be provided and used.Where appropriate to the task in hand, protective equipment (ie screens, goggles, respirators, safety belts, protective clothing etc) must be used.Ensure adequate lighting is provided, permanent or temporary.Do not lift, move or carry loads that are liable to cause personal injury. Use lifting tackle or other suitable lifting gear.All work areas must be kept as clean and tidy as possible consistent with use. Dirt and refuse must not be allowed to accumulate.Ensure adequate ventilation is provided at all work areas. Special precautions must be taken where steam, smoke, refrigerants, asbestos or other unhealthy or dangerous contaminants are present in confined spaces.Before undertaking any welding, brazing or such like, a ‘Hot Permit to work’ must be obtained from an authorised NHS Estate Officer.Observe all fire precautions. All Trust sites operate a ‘No Smoking Policy’ that must be observed.Ensure a clear means of escape from work areas. Escape routes maintained must be kept free of obstructions at all times.Take note of all fire fighting equipment and become familiar with Trust Fire procedures. This information shall be made available to contractors by each NHS Trust.Do not touch or insert objects onto any items of stationary rotating equipment as it may be remotely controlled and could therefore automatically start without warning.Use correct grease, lubricants ie only brands and grades as recommended by the equipment manufacturer. Ensure adequate lubrication, but avoid excess, wipe off any spillage on equipment and thoroughly clean floor if spillage has occurred.Always replace drive guards correctly if removed.Under no circumstances should any attempt be made to remove a component or cover on a unit which forms part of a refrigeration circuit before making certain that no pressure is present on the refrigerant side of item.Readings relevant to refrigeration systems are not to differ significantly from those on previous log sheets or commissioning data, unless changes can be attributed to changes in cooling load or in ambient conditions. Where a reading is out of tolerance, determine the cause and maintain repair or adjust the offending item. Note details of remedial action taken and record final settings obtained.Use only instruments for taking measurements, which have been certified as being checked and calibrated against instruments of known accuracy.Cassette and split type cooling systemsa)Inspect installation externally and record all observations. Note external/internal ambient conditions.b)Check unit for correct operation and note any unusual vibration, noise or odour.ci)Check casings, ductwork, louvres, fixings, anti-vibration mounts, flexible connections, insulation, louvres for signs of corrosion and deterioration.di)Check drip trays, eliminator plates and drain lines.dii)Clean out drip trays and drain lines and ensure condensate runs away freely, ensure pipework is properly supported. Disinfect drip trays and condensate drain lines. Top up trap seals if fitted.e)Check all 1.e.d.s and lamps. Replace faulty lamps/1.e.d.s.f)Advise authorised NHS Estate Officer of any further work required for the plant to operate satisfactorily to the next service maintenance visit.Unitary cooling unitsDutiesCarry out duties as listed under section 3.0 Cassette and Split Type Cooling Systems.Air cooled packaged chillersa)Inspect installation externally and record all observations. Note external/internal ambient conditions.b)Check unit for correct operation and note any unusual vibration, noise or odour.ci)Check casings, ductwork, louvers, fixings, anti-vibration mounts, flexible connections, insulation, louvers for signs of corrosion and deterioration.cii)Tighten all fixings, bolts, supports and fasteners etc. Change damaged flexible joints and anti vibration mounts.di)Check refrigerant pipework, that can be accessed (ie do not remove ceiling tiles) for signs of leaks using a halide lamp or electronic leak detector. If leak detector becomes saturated, locate approximate position and then pin point position by using soapy water applied by brush.dii)If a leak is present contact an authorised NHS Estate Officer immediately and provide him with the opportunity to witness failure, evacuate the refrigerant; this will also be necessary if non condensable gas, air or moisture is present – by the use of a vacuum pump. This activity is to be chargeable.Ensure no internal pressure is in the unit, all pressure must be removed without venting into the atmosphere. Connect service hoses of gauge manifold to check joint of gas and liquid piping. Connect vacuum pump to change hose and repeat evacuation procedure as per manufacturers recommendation. Cautionary note: Do not use refrigerant pressure to expel air. Do not use compressor for evacuation. Do not operate compressor in vacuum condition.Within 24 hours provide the authorised NHS Estate Officer with a quote to repair/replace damaged section of system and recharge system with refrigerant. Await this instruction to proceed and if given, record weight of refrigerant used. On completion check for gas leakage using a leakage detector and if satisfactory, operate the unit; record high side and low side pressures and temperature difference between suction air and outlet air.e)Examine any data supplied by the equipment manufacturer.f)(i)Check oil level in sump or crankcase.(ii)Check oil differential pressure (ie oil gauge pressure minus crankcase or oil sump pressure). When the oil pressure gauge is of the differential type, the direct reading is to be recorded.(iii)Check that oil sump heater or crankcase oil heater (if fitted) functions when the compressor is not running.(iv)Check temperature of lubricating oil leaving oil cooler.(v)Check that crankcase oil cooler (if fitted) functions when the compressor is running.(vi)Inspect cooling water control valve on oil cooler.(vii)Check date of last oil change.(viii)With compressor at rest, check shaft gland seal for refrigerant and/or oil leakage visually and using a halide-test lamp (open type compressors only).(ix)Check that cylinder unloading mechanism, if fitted on reciprocating type compressors, loads and unloads cylinders in the sequence and at the correct setting.(x)Check operation logbook, if in use, for evidence of high compressor refrigerant discharge temperature.g)Ensure oil level in crankcase or sump is as stipulated by manufacturer.h)Ensure high oil level is not due to the presence of two liquids or vigorous foaming in the sight glass.i)Ensure oil differential pressure is above the minimum stipulated by manufacturer. Note compressors must be at rest when checking crankcase or sump heaters. Change cartridge type filter if necessary.j)Check crankcase/sump heaters for tightness in their mountings.k)Check compressor discharge temperature does not exceed value stipulated by manufacturer.l)In event of semi-hermetic motor/compressor suffering a burn out advise an authorised NHS Estate Officer immediately.m)For reciprocating compressors, ensure the maximum temperature attained by the crankcase oil, with compressor running and oil cooler in operation, does not exceed that stipulated by manufacturer.n)For reciprocating compressors top up lubricating oil to correct level using only oil as stipulated by manufacturer.o)For reciprocating compressors if the following items are found to be defective, then within 24 hours provide an authorised NHS Estates Officer with a quote to replace: heater, thermostatic expansion valve or solenoid valve serving an oil cooler, replace time expired oils, defective shaft gland seal, faulty unloading mechanism or reset control equipment and damaged compressor delivery valves.p)For screw compressors change cartridge type oil filter if differential oil pressure is low and if unsuccessful investigate defects in oil pump or oil pressure relief valve.q)For screw compressors clean oil cooler where excessive oil exit temperature is indicated.r)For screw compressors if the following items are found to be defective, then within 24 hours provide the authorised NHS Estate Officer with a quote to replace: water control valve, oil return valve, heater element, strainer/filter (if in good condition – clean and replace), fibrous oil separation element and shaft gland seal.s)Delivery oil separator as follows: Examine data provided by equipment manufacturer, inspect and check correct operation of automatic oil return valve, service or repair oil valve as necessary.Inspect oil strainer or filter. Clean dirty filter.)Liquid line sight glass.(i)Check and ensure optic glass is not cracked. Replace if damaged.(ii)Ensure all stop valves preceding sight glass are fully open.(iii)Ensure strainer, built into sight glass unit, is clean, clean if necessary.(iv)Check for refrigerant leaks around the assembly using a halide lamp. Repair as necessary. (Subject to agreeing).u)Filter Drier Unit.If moisture is found to be present renew sealed type filter/drier unit or renew the cartridge of a serviceable type unit.v)Solenoid Valve.(i)Check and ensure correct operation of solenoid valve. Service valve if necessary, renew leaking valve seat(ii)Check and ensure integral strainer is clean. Clean strainer as necessary.(iii)Check all pilot holes and pipework. Clean obstructed pilot holes and pipework.w)TEV(i)Check security of thermal sensing bulb on suction pipe from evaporator or cooler. Tighten fastenings and make sure no corrosion is present.(ii)Check position of thermal sensing element. Ensure compliance with manufacturer’s data.(iii)Check temperature of refrigerant gas passing a thermal element and compare with manufacturers data. Reset using adjustment mechanism if necessary.(iv)Check condition of inlet filter. Clean as necessary.x)E V Float Operated Expansion Valve.(i)Check manufacturer’s data.(ii)Check for modulation action observed through sight glass on float chamber of the expansion valve. If no sight glass fitted, inspect level of refrigerant in evaporator using level gauge or sight glass.If fluctuation present under steady load then investigate bearings of butterfly valve spindle for smooth operation, investigate needle valve for smooth sliding action in seat, check float does not contain refrigeration liquid, or is leaking. If foregoing checks do not reveal a fault, advise an authorised NHS Estate Officer immediately.y)Hot Gas By Pass(i)Check Manufacturer’s data.(ii)Observe a suction pressure gauge and ensure pressure remains at specified value while plant load varies. Adjust valve maintaining an incorrect suction pressure. Repair or renew a faulty valve.(iv)Check refrigerant gas superheat temperature at compressor suction. If outside limits, adjust liquid injection valve (where fitted). Check refrigerant temperature at compressor discharge when plant load is low.(v)If hot gas entry point is into the suction pipe, observe position of thermal element of main expansion valve relative to entry point. Move terminal sensing element affected by hot gas by-pass further down stream of hot gas entry point.z)Evaporator Pressure Regulating Valve.(i)Check, by means of pressure gauge upstream of evaporator pressure regulating valve, the pressure is maintained at or above value specified. Adjust an incorrectly set valve otherwise repair or renew as necessary. (Advise and submit quotation within 24 hours if renewal is necessary).aa)Suction Pressure Regulating Valve(i)Check manufacturer’s data.(ii)Observe suction pressure gauge immediately after compressor starts on a high duty condition and check that suction pressure does not rise above specified value. Adjust incorrectly set valve. Otherwise repair or renew faulty valve. Advise and submit a quotation within 24 hours if renewal is necessary.bb)Condenser Fans(i)Inspect condenser fan impellers and motors for correct operation and sequencing.cc)Evaporator(i)Check for leaks. If leak present carry out duties given in 5.1 dii).(ii)Check insulation for damage and deterioration. Repair as necessary.(iii)Check operation of electrical trace heating and controls.dd)Control Panel(i)Check control panel and all electrics for safety.(ii)Check all door seals of control panel. Repair as necessary.(iii)Check all safety interlocks such as flow switches etc.ee)Wipe down unit and leave in operating condition.ff)Advise of any further work required for the plant to operate satisfactorily for the next service maintenance visit.Cold Rooms and Mortuary Body Storesa)Inspect installations externally and record all observations.b)Carry out duties items as listed under Section 5.0 (Air Cooled Packaged Chiller).c)Examine all modular cold rooms panels and components for damage and deterioration paying attention to sealants and the like. Repair as required any minor damage and reseal as necessary – use only food grade materials.d)Check correct functioning of all controls, interlocks and alarms.e)Examine condition of evaporator coil block. Clean dirty and fouled coiled block. (There should be no evidence of frost or ice).f)Examine drain tray and pipe. Clean out drain tray and ensure pipes are clear and unobstructed.g)Check operation of trace heating to drain pipes.h)Examine evaporator casing. Tighten all nuts bolts and fasteners. Treat for corrosion.i)Examine and where necessary adjust and lubricate: Sealing gaskets, door locks, hinges, handles, sliding drawers and the like, door alignment and security of fastenings.j)Advise of any further work required for the plant to operate satisfactorily to the next service visit.DX coils/condenser unitsa)Inspect installation externally and record all observations. Note external/internal ambient conditions.b)Carry out all duties as listed under Section 5.0 (Air Cooled Packaged Chillers)c)Advise an authorised NHS Estate Officer if any further work required for the plant to operate satisfactorily to the next service maintenance visit.Air handling units DX coil and chilled water coilsa)Inspect installation externally and record all observations. Note external/internal ambient conditions.b)Check unit for correct operation and note any unusual vibration, noise or odour.ci)Check casings, ductwork, louvers, fixings, anti-vibration mounts, flexible connections, insulation, louvers for signs of corrosion and deterioration.cii)Tighten all fixings, bolts, supports and fasteners etc. Change damaged flexible joints and anti vibration mounts. Reinstate damaged insulation paying particular attention to the preservation of any vapour barrier and labelling. Clean down and repaint or renew any corroded component. All deteriorated metal is to be wire brushed, given one coat primer and two finishing top coats.c)Check condenser fan impeller, shaft and bearings. Clean fan impeller and motor. Lubricate bearings. Tighten loose keys or fastenings and rebalance if required.ei)Check drip trays, eliminator plates and drain lines.eii)Clean out drip trays and drain lines and ensure condensate runs away freely, ensure pipework is properly supported. Disinfect drip trays and condensate drain lines. Top up trap seals if fitted.fi)Check refrigerant pipework, that can be assessed (ie do not remove ceiling tiles) evaporator and condenser for signs of leaks using halide lamp or electronic leak detector. If leak detector becomes saturated, locate approximate position and then pin point position by using soapy water applied by brush.fii)If a leak is present, contact an authorised NHS Estate Officer immediately and provide him with the opportunity to witness the failure, it will be necessary to evacuate the refrigerant, this will also be necessary if non condensable gas, air or moisture is present – by the use of a vacuum pump. This activity is to be chargeable. Ensure no internal pressure is in the unit, if pressurised then relieve through a check joint. Connect service hoses of gauge manifold to check joint of gas and liquid piping. Connect vacuum pump to change hose and repeat evacuation procedure as per manufacturers recommendation. Cautionary note: Do not use refrigerant pressure to expel air. Do not use compressor for evacuation. Do not operate compressor in vacuum condition. Within 24 hours provide the customer with a quote to repair/replace damaged section of system and recharge system with refrigerant. Await his instruction to proceed and if given, record weight of refrigerant used. On completion check for gas leakage using a leakage detector and if satisfactory, operate the unit; record high side and low side pressures and temperature difference between suction air and outlet air.g)Inspect and clean DX coil fins in AHU.h)Inspect and clean debris from condenser unit intake louvres.i)Check all motors and complete system for electrical safety.j)Check all LED’s and lamps.k)Replace faulty lamps/LED’s.l)Run unit and check for correct operation.n)On chilled water Systems check: Chilled water coil for leaks, correct operation of control valves, ensure control valve linkage is free to travel, adjust and calibrate thermostats, sensors for proper control, check and adjust chilled water pumps belts and pulleys for correct tension and speed, bleed off air from chilled water coil, advise of any damage/deterioration to insulation on chilled water pipework and clean out eliminator plates and drip trays to chilled water coils if fitted and advise of internal condition of AHU.n)Advise authorised NHS Estate Officer of any further work required for the plant to operate satisfactorily for the next service maintenance visit.Upright refrigerator units and cold display unitsa)Check cabinet and external controls and record observations.b)Examine and where necessary adjust and lubricate: Door locks, hinges, handles, sliding drawers and the like, door alignment, security of fastenings and sealing gaskets.c)Check thermal insulation for damage.d)Examine the condenser and check security of fixings, coil is clean and in good condition without damaged fins or pipes. Remove dust and debris and ensure good air movement across the coil.e)Check means of collecting and disposing of defrost water. Clean out drain tubes.f)Visually check for electrical safety.g)Check operation of all alarms, thermostats, pressure switches, contactors and overload devices are making good electrical contact and that all lamps are functioning.h)Inspect open drive compressors for correct alignment and proper belt tension and condition.i)Check guards are in place and secure.j)Advise an authorised NHS Estate Officer of any further work required.Fgas RegulationsOperators (ie owners) of stationary refrigeration, air-conditioning and heat pump systems containing F Gases have a legal obligation to keep certain system records under EC F Gas Regulation 843/2006 article 3 and supporting Regulation EC 1516/2007.This applies to all systems with more than 3 kg of HFC refrigerant (or 6kg if hermetically sealed and labelled. The obligation came into force on 4th July 2007.Within this contract the servicing and inspection of cold rooms, glass freezers, split package air conditioning and large central chiller plant shall be carried out in total conformity with the Fgas Regulations which came into force on the 4th July 2007.The obligations of the Fgas regulations are categorised as follows, -<3 kg>3 but < 30 kg>30 kg but < 300kg>300 kgThe successful tenderer shall carry out the contract in line with the obligations of The User as laid out within the Fgas Regulations and maintain the requisite records on behalf of the Trust within the cost of the contract. This record shall be fully reported electronically on an annual basis and shall be available for inspection at all times.The successful contractor shall be registered and fully compliant with REFCOM, utilizing certified operatives, correct equipment and maintaining a refrigerant tracking audit system.