Download CROWDYS HILL SCHOOL REDEVELOPMENT

CROWDYS HILL SCHOOL
REDEVELOPMENT – NEW PRIMARY SCHOOL
MECHANICAL SPECIFICATION
Contents
1.0 Outline of Works
2.0 Water Services
3.0 Heating
4.0 Gas Service
.
5.0 Ventilation
6.0 Fire Sprinkler System
7.0 Thermal Insulation
8.0 Commissioning
9.0 Mechanical Services Pricing Breakdown
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1.0 Outline of Works
1.1 Introduction
The nature of the works is to design and provide a new mechanical services installation
to Crowdys Hill School, Swindon.
The mechanical services work will provide a safe and durable mechanical system of a
high standard taking account of the architecture and level of finishes within the project.
The work shall meet all current statutory requirements and recognised United Kingdom
Regulations.
All workmanship and materials used must be of the highest quality and attention to detail
must be paramount within this building.
1.2 Scope of Works
The mechanical services installation includes the design, supply, works testing, delivery,
off-loading, storage, installation, site testing, commissioning, and setting to work the
mechanical services described in this specification.
The completeness of the installation shall comprise the equipment listed in this
specification and all other components necessary for the correct operation in accordance
with the design intent.
A high standard of finish is intended to the property both internally and externally. The
services will be required to reflect this in all aspects.
The mechanical services installation shall comprise the following works:
1) Incoming gas and main cold water services.
2) Ventilation systems serving toilets and ancillary areas.
3) Heating system providing heating to all areas.
4) Hot water services.
5) Mains fed cold water services taken from the incoming cold water main supply.
6) Thermal insulation to all mechanical services.
7) A control system including all control elements and associated electrical and control
wiring.
8) The production of record drawings based on a site measure. Record drawings are to
be produced as hard copy.
9) The commissioning testing and setting to work of all mechanical services systems and
plant and documentation of same.
10) Minor items of builders work such as small holes in non-structural walls, ceilings and
chases etc. together with making good of same to the required fire rating.
1.3 Design Criteria
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The design criteria for which the systems shall be designed and to which they should be
installed and commissioned are as follows:
1.3.1 External Design Criteria
Summer: 28oC DB 20oC WB
Winter: -3oC DB 100% RH
1.3.2 Internal Design Criteria
Classrooms: 21oC
Toilets: 20oC
All other spaces: 18oC
Maximum pipe velocity: 1.5m/s
Maximum pipe pressure: drop 300Pa/m
The following water flow rates shall be provided at the hot and cold services outlets;
WC’s: N/A 0.10l/s
Wash Basins: 0.15l/s 0.15l/s
Showers: 0.1l/s combined hot and cold
Sinks: 0.20l/s 0.20l/s
Minimum pressure at each outlet: 0.5 bar
Hot water storage temperature: 60oC
Hot water circulation temperature: 55oC
Hot water outlets in all areas that are accessible to pupils shall be fitted with thermostatic
mixing valves to limit the hot water temperature to 43 oC.
All areas are provided with natural ventilation via openable windows or rooflights.
The following areas are to be provided with mechanical ventilation:
Toilets: 6 air changes per hour
1.4 Standards
The mechanical services installations shall be designed and shall be installed to comply
with all current statutory instructions and regulations. These shall include but not be
limited to:
Building Regulations 2000 and all subsequent amendments
Building Regulations 2000 – Part L2A Conservation of fuel and power
Requirements of the Building Control Officer and District Surveyor
British Gas Board regulations
BS6700: Specification for the design, installation testing and maintenance of services
supplying water for domestic use within buildings and their curtilages.
Public Health Act 1936 and 1961
Water Authority Bye-Laws
Health and Safety at Work Etc. Act
CDM regulations
Local Authority requirements
Related British Standard Specifications for equipment and workmanship
Related British Standard Codes of Practice for materials, equipment and workmanship
Chartered Institute of Building Services Engineers design guides
Chartered Institute of Building Services Engineers commissioning codes
Manufacturers stipulations and recommendations for installation, testing and
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Commissioning
1.5 Design Responsibility
The mechanical services systems shall be designed by the Contractor who will have
responsibility for the correctness of the information they produce.
The Contractor shall arrange services to provide the optimum layout for the installation
and future maintainability of the systems.
1.6 Health and Safety at Work Act
The Contractor shall appoint an authorised person who shall be responsible for the
control of electrical danger associated with the appropriate parts of the electrical
installation for the duration of the contract period.
Authorised person shall be as defined in the Electricity at Work Regulations 1989 issued
by the Health and Safety Commission.
The appropriate parts of the electrical installation shall be as follows:
1) All electrical services within the areas affected by the works.
2) Any distribution board or motor control centre providing supplies to these areas.
3) Any item of switchgear controlling/protecting the sub-main circuits to the distribution
boards mentioned above.
3) The Contract Programme as indicated in the tender documents.
At no time shall any supplies to the existing school be isolated without the approval of
the Contract Administrator.
At no time shall the Contractor or his sub-contractors work on any electrical circuits in
which both the phase and neutral poles have not been isolated. The Contractor shall
ensure that the supply is isolated by either physically removing the links or fuses or by
locking devices in the “OFF” position using a unique/dedicated locking mechanism.
Substantial warning notices shall be securely fixed to the isolating device clearly labelled
“DO NOT OPERATE THIS DEVICE, THIS SUPPLY IS THE RESPONSIBILITY OF
(Contractor’s name, address and telephone number where the authorised person can be
contacted 24 hours per day)”
Before commencing any work all poles shall be tested to ensure that they are electrically
“dead”. The Contractor shall be responsible for providing warning notices at all areas of
work.
1.7 Incoming Services
New incoming gas and water services are to be provided to the new development.
The new supplies will be negotiated by the Contractor with the local supply authorities,
who will install the new supply meters.
Incoming services will be extended from the supply authority meters.
1.8 Builders Work
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Major items of builder work associated with the mechanical works shall be undertaken by
the Contractor to details provided by the Mechanical Sub-contractor. Such items shall
include:
1) All concrete plinths and bases in plant rooms
2) All openings in structural walls of the building
3) Trimming of floor structure to provide services routes for both vertical and horizontal
ductwork, pipework and drainage.
1.9 Electrical Works
The installation of the electrical power distribution system and lighting installation
including all mechanical wiring but excluding control wiring shall be undertaken by the
Electrical Sub-contractor.
This work shall include the supply and installation of power cabling from the main
distribution board.
1.10 Temporary Electricity for the Works
Temporary electricity supplies to hand held appliances shall be 110V 50 Hz supplied by
a transformer with the secondary winding centre tapped to earth.
The Contractor shall allow for power utilised on site during the installation and testing of
the works.
1.11 Asbestos
Materials containing asbestos shall not be used nor incorporated into the works.
1.12 Fire Sealing
The Contractor shall undertake fire sealing of openings formed for services to pass
through the fire compartment barriers.
Fire sealing shall only be applied to completed and tested services. Fire dampers are to
be as indicated and shall be provided with frames to be built into the structure by the
Contractor.
1.13 Maintenance
The Contractor shall include for maintaining the completed mechanical installations for a
period of 12 months from the date of practical completion.
The maintenance works shall include an allowance for all consumable materials such as
filters, chemicals for water treatment, lubricants etc. These may be estimated separately
on a quantity basis.
1.14 Handover Procedures
The Contractor shall include for the issue of all specified drawings, operating and
maintenance manuals, short form operating instructions, chemicals, spares and
consumable items.
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The spare filters called for shall be handed over new and unused. In addition, filters used
during testing and commissioning shall be replaced immediately prior to handover such
that the plant is handed over in a fully operational condition.
In addition to the above the whole of the mechanical services installation shall be
demonstrated to the Site Manager. The Contractor shall allow sufficient time for
instruction by a competent person.
1.15 Post Handover Attendance
The Contractor shall rectify all defects arising after completion and shall attend to the
maintenance requirements of the mechanical services.
The Contractor shall allow sufficient time in additional attendance by a competent
commissioning engineer to modify system settings as directed by the Contract
Administrator. The purpose of such attendance is to fine tune the systems as operational
experience is gained and the need to alter air balances, flow rates, temperatures etc. is
established. All record documentation must subsequently be amended.
1.16 Contractual Authorities
Client
Swindon Borough Council
Property Services
2nd Floor Wat Tyler West
Beckhampton Street
Swindon Borough Council SN1 2JUH
Tel: 01793 463619
Contractor
To be confirmed
1.17 Co-ordination of Installations
The Contractor shall liaise with the Mechanical Sub-contractor to ensure the works are
carried out in a proper co-ordinated manner. Claims for removal of completed works to
allow access for other Sub-contractors will not be considered.
It shall be the Mechanical Sub-contractors responsibility to bring the Contractors
attention, prior to installation, any instance where he believes installation difficulties or
coordination problems may exist.
1.18 Record Drawings
Record drawings of the installation, based on the installation drawings, shall be prepared
and submitted to the contract administrator. They shall be complete in all respects and
shall accurately locate and reference all components of the systems to enable them to
be properly maintained, serviced, repaired and allow component replacement.
The record drawings, once approved, shall be incorporated into the operating and
maintenance manuals as described below.
1.19 Operating and Maintenance Manuals
The Contractor shall include three operating and maintenance manuals for the
mechanical services installed under the contract.
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The manuals shall fully describe the services installed in the building, including detailed
information about the controls system. The manual shall include details of all items of
plant installed including manufacturer’s data sheets and manufacturer’s operating and
maintenance instructions. The manual shall also include a schedule of routine planned
preventative maintenance for the building to ensure that the plant is operating at its most
energy efficient at all times.
1.20 Building Log Book
In addition to the comprehensive operating instructions detailed in section 1.19, the
Contractor shall also provide one bound A4 copy of the building log book as required by
the Approved document L2A of the Building Regulations. The building log book shall be
written in the format and following the advice given in TM31:2006 Building log book
toolkit published by the Chartered Institute of Building Services Engineers (CIBSE).
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2.0 Water Services
2.1 Extent
The water services shall be provided as described in this specification.
The new water services shall comply with the requirements of BS 6700 and all
components of the water systems shall be WRC approved and listed in the “Water
Fittings and Materials Directory”.
The water services consist of:1) Application for and management of new metered cold water supply
2) Mains cold water to all cold water outlets
3) Mains fed hot water to classroom toilets via local electric heaters
4) Mains fed hot water to hall block via gas fired water heater
5) All final connections to outlets using WRC approved flexible pipes.
All water pipework not exposed to view is to be insulated in accordance with this
specification.
2.2 Mains Cold Water Service
The Contractor shall be responsible for obtaining a quotation, placing an order and
managing Thames Water in the installation of the new cold water supply.
From the supply authority meter run a new MDPE cold water main to supply the school.
Each point of entry is to be fitted with a stopcock and drain cock.
From the entry point run a system of copper pipework to serve all cold water outlets and
the hot water heaters. Generally pipework is to run in the ceiling void of the toilets and
the corridor of the hall block, dropping to low level to serve the outlets.
All cold water outlets are to be fitted with water flow regulating devices to provide the
flow rates identified under design criteria.
The Contractor shall include for chemical cleaning and sterilisation of the installation on
completion of the works.
All necessary plant, equipment, pipework, pipework ancillaries, insulation, controls,
testing, flushing, commissioning, supports and operating and maintenance manuals shall
be provided to form a complete installation.
2.3 Domestic Hot Water Service
Hot water to the hall block is to be provided by an unvented gas fired water heater
located in the plantroom.
Provide a system of copper pipework to distribute the hot water to the outlets identified.
Generally the pipework shall be installed in the ceiling void above the corridor.
The hot water system is to be provided with a return pipe to provide circulation of the hot
water and maintain a minimum temperature in the hot water system of 55oC.
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All hot water circuits are to be provided with a regulating valve to allow the system to be
balanced correctly.
Mains fed domestic hot water is to be provided to the toilets in the classroom blocks by
an electric water heater, located at high level above the basins.
All water heaters are to be provided with expansion vessels, pressure relief valves etc. to
form a complete safe installation. Pressure relief valves are to discharge via a tundish
into a safe location.
All hot water outlets in areas accessible to pupils shall be fitted with a thermostatic
mixing valve to limit the hot water temperature to 43oC.
Provide an oversink water boiler to provide hot water for making tea, coffee etc. in the
staff room.
All hot water outlets are to be fitted with water flow regulating devices to provide the flow
rates identified under design criteria.
The Contractor shall include for chemical cleaning and sterilisation of the installation on
completion of the works.
All necessary plant, equipment, pipework, pipework ancillaries, insulation, controls,
testing, flushing, commissioning, supports and operating and maintenance manuals shall
be provided to form a complete installation.
2.4 Gas fired water heater
Provide and install in the plantroom one Ecosheild high efficiency gas fired condensing
storage water heater as manufactured by Lochinvar Ltd model number SHW85-435CE.
The water heater shall have a recovery rate of 1379 litres per hour @ 50 oC DT.
The water heater shall be manufactured to ISO 9001 standards and shall be CE
approved and supplied to site preassembled.
The water heater shall be floor mounted condensing type supplied with all necessary
electronic temperature and safety controls. The burners shall be low Nox (<59mg/kWhr).
The water heater shall be fitted with an un-vented system in accordance with approved
document G3, BS6700 and the manufacturer’s recommendations for direct mains feed
system installations. Safety equipment is to include but not be limited to pressure
reducing valve, non-return valve, 25 litre expansion vessel, Pressure relief valve and
temperature/pressure relief valve.
The discharge from the temperature/pressure relief valves is to discharge to a safe place
via a tundish.
2.5 Electric water heaters
Provide and install at high level in the toilets a multipoint electric water heater to provide
hot water to the outlets.
The water heater shall have a storage capacity of 15 litres and be fitted with a 3kW
electric immersion heater complete with integral adjustable thermostatic control.
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The water heaters are to comprise a replaceable heavy gauge copper inner container,
designed for 6 bar working pressure. The outer casing is to comprise a white plastic top
moulding with steel base and centre section finished in white stove enamel.
The water heater is to include a factory fitted pressure relief valve set to open at 7 bar or
a 90oC resettable over temperature cut out.
Electric water heaters are to be as manufactured by Heatrae Sadia or equal approved.
2.6 HWS Secondary circulation pump
Provide and install in the plantroom a secondary circulation and distribution c/w
regulating valves to provide a minimum return water temperature of 55 oC and specified
outlet temperatures within 50 seconds.
HWS circulating pump shall be bronze single head type suitable for potable water,
manufactured and supplied by Grundfos pumps ‘A’ energy rated or equal. The pump
shall be provided and installed adjacent to the water heater and complete with isolating
valves and flexible connections.
Installation of each pump shall be strictly in accordance with the manufacturers
recommendations and particular care shall be taken to ensure that no undue vibration is
transmitted to the associated structure or pipework.
The pump motors shall be rated IP54, high efficiency EFF1 and motor windings shall be
limited to 80oC rise at maximum output.
2.7 Pipework and Fittings
Externally buried cold water pipework shall be WRAS approved, blue medium density
polyethylene (MDPE) pipe and fittings for installation below ground, for working
pressures up to 15 bar and temperatures up to 40oC. Pipes shall be manufactured and
tested to BS6572 for pipework up to and including 63mm and WRC specification WIS
4.32.03 for pipework 90mm and above.
Above ground pipework shall be installed in copper tubing to BS 1057:2006 with capillary
and compression fittings and joints to BS EN1257, to the general requirements of this
specification.
Capillary fittings shall be utilised in all service voids, shafts and ceilings. Compression
fittings shall be used for valves and for connection to sanitary fittings, plant and
equipment. All overflows, flushing pipes and discharge pipes to drain shall be installed
with compression fittings. Capillary joints shall be made using solder complying with BS
EN ISO 9353. Lead based solder shall NOT be used.
2.8 Pipework Supports
Pipework shall be supported by two piece brass clips at spacings no greater than those
stated in the British Standard.
2.9 Valves
Incoming main cold water supplies shall be provided with isolation at the point of entry
using a stopcock to BS1010.
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All isolating valves shall be WRC approved. They shall be spherical ball valves, quarter
turn with lever handles for sizes 54mm and below. Valves shall be manufactured by
Hattersley fig 100 or equal.
The Contractor shall ensure that all water distribution pipework includes sufficient valves
for isolation and drain valves.
All drain cocks shall be as manufactured by Hattersley or equal fig 371.
Isolating valves to individual draw-off points shall be of the combined isolating valve and
flow regulator type as manufactured by Robert Pearson or equal.
Thermostatic mixing valves shall be approved by the TMV scheme and meet the
requirements for a type 3 valve. Valves shall be supplied with flat faced union couplings,
isolating valves, strainers and integral removable check valves factory pre-set to 43oC
but with simple adjustment and locking system for each on site application.
Valves shall have a nickel plated DZR copper alloy body and connections suitable for
both 22mm and 15mm pipework and encapsulated in a white plastic cover. WRAS
approved product as manufactured by Horne Ltd or equal.
2.10 Hydraulic Testing
Upon completion, but before the pipe service becomes obstructed by other trades or
other services and before insulation is applied, the water services systems shall be
thoroughly flushed through and subjected to a pressure test of the greater of one and a
half times the normal working pressure or 7 bar. The test shall be applied for a period of
two hours, witnessed by the contract administrator and certificates issued in triplicate.
Testing shall be carried out to the requirements of BS 6700:1987.
If necessary testing shall be carried out in sections and shall be a continuous exercise
executed by the Contractor during the progress of the works, to provide the installation
and quality of materials are in accordance with the specification.
Where sections of the work are to be built in or covered over, the tests are for the benefit
of the contractor to ensure that delays in construction works do not occur due to the
taking down or removal of any wall, partition, ceiling or floor which may be required to
enable remedial works to be undertaken to any section of a system failing during system
testing and commissioning.
The Contractor shall ensure during hydraulic testing that all items of equipment are
isolated from the system.
2.11 Disinfection
On completion of the water services installation and after all testing is complete, the
entire installation shall be thoroughly and efficiently disinfested in accordance with
BS6700:1987.
The Contractor shall arrange for the sterilisation to be carried out by a specialist firm and
notify the Local Water Authority, Contract Administrator and Site Manager as to when
the sterilisation is to be undertaken.
Sterilisation is to be undertaken by Aldous and Stamp Ltd or equal and approved.
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The sterilisation procedure shall be carried out in the following manner:
1) Warning notices shall be displayed at every outlet on the system and at all relevant
valves.
2) The entire mains water system and drinking water system shall be sterilised by
injection. Whilst the sterilant is being injected, all services and outlets shall be run
until the chlorine level at each of these is above 50ppm. This is to be carried out
without risk of contamination to the Statutory Authority’s main.
3) All cylinders and hot water distribution services (including pumped services where
applicable) shall be run until the chlorine level in and at each of these is above
50ppm. The Contractor shall be responsible for maintaining the system in this
condition and ensuring that no water is drawn from it by others.
4) After a contact period of not less than three hours, tests for the residual chlorine shall
be carried out at random points on each system. If any of these points reveal that the
chlorine level has dropped 20ppm, the sterilisation programme shall be repeated until
satisfactory levels are obtained.
5) The entire system shall be left undisturbed for a total of 24 hours. Upon the
successful completion of the sterilisation, the entire installation shall be thoroughly
flushed until the chlorine level throughout the each system, and at each outlet, is
below 0.3ppm. The warning notices may then be removed.
2.12 Bacteriological Testing
The Contractor shall arrange for samples of water to be taken for bacteriological analysis
after flushing is complete.
The techniques for sampling and examination to ensure proficiency of laboratory practice
and comparability of results and the interpretation of these results shall be as
recommended in H.M.Government Report ‘The Bacteriological Examination of Drinking
Water Supplies 1982’.
The samples shall be obtained from a suitable test point from each of the services
detailed below, where applicable:
1) Mains water service entering the property.
2) Extremity of the mains water distribution service.
3) Extremity of the hot water distribution service.
The biological examination of each and every sample must show the waters to be free
from contamination and of a potable quality before the sterilisation programme may be
regarded as effective.
Upon receipt of satisfactory results the systems may be regarded as fully operational. No
further or additional work, including draining down, shall be carried out on the systems
without the prior consent of the Contract Administrator as this may result in a rechlorination being called for.
The Contractor shall obtain from the specialists appropriate reports and certificates
relating to the sterilisation programme and bacteriological examinations, and forward
these to the contract administrator to ensure a potable water system is available.
The Contractor shall allow for all costs relating to sterilisation and bacteriological
analysis.
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2.13 Commissioning of the Hot Water System
The hot water systems shall be regulated and balanced to by establishing correct
circulation temperatures so that no part of the circulating water drops below 50 oC.
Lockshield valves shall be provided throughout the system as is necessary to ensure
circulation throughout all branches of the pipework system.
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3.0 Heating
3.1 Extent
The building has been designed to allow construction on a modular basis and the
heating system has been divided up to reflect this approach.
Each boiler is to be provided with a gas supply, cold water make up connection, safety
valve and expansion vessel to form a complete safe installation.
The flue from the boiler in the plantroom will rise directly through the roof of the
plantroom. The flues from the other boilers will rise into the ceiling void and run to a
suitable safe position and rise through the flat roof to discharge to outside. All flues will
be fitted with a suitable flashing and cowl.
The boilers are to be controlled by a local 7 day programmable timeswitch with two on
and two off periods per day, the timeswitch is also to allow setting of holiday periods.
The timeswitch is to include an override button to allow the heating to be switched on or
off and to remain in that condition until its next operation or until the override is operated
again.
The spaces in the building are to be heated using underfloor heating.
The underfloor heating will be controlled by tamperproof thermostats within the spaces to
be controlled.
All necessary plant, equipment, pipework, pipework ancillaries, insulation, controls,
testing, flushing, commissioning, supports and operating and maintenance manuals shall
be provided to form a complete installation.
3.2 Boilers
Each boiler shall be manufactured to ISO 9001 standards and shall be CE approved and
supplied to site preassembled.
Boilers shall be wall mounted condensing type supplied with all necessary electronic
temperature and safety controls. The boiler burners shall be ultra-low Nox (<45mg/kWhr)
fully modulating (20-100%) output. The boiler burners shall be controlled to ensure that
the gas/air ratio is at a level where the maximum efficiency and minimum emissions are
achieved, and shall have a minimum 92% gross efficiency.
Boilers shall be as manufactured by Broag Remeha from their Quinta range sized as
follows:
1) Classroom + Toilets Quinta 45 – nominal output 8.0 – 40.0 kW @ 80/60oC
2) Classroom block Quinta 30 – nominal output 5.6 – 28.0 kW @ 80/60oC
Each boiler shall be provided with a 20mm safety valve and a 50 litre expansion vessel.
Expansion vessels shall be constructed of mild steel generally in accordance with
BS4814 and BS5169.
Condensate drains shall be run in plastic pipework and run to discharge in a suitable,
safe location.
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3.3 Circulating pumps
LTHW circulating pumps shall be single head type, manufactured and supplied by
Grundfos pumps A energy rated or equal.
Pumps shall be provided and installed adjacent to the boiler and complete with isolating
valves and flexible connections.
Installation of each pump shall be strictly in accordance with the manufacturers
recommendations and particular care shall be taken to ensure that no undue vibration is
transmitted to the associated structure or pipework.
The pump motors shall be rated IP54, high efficiency EFF1 and motor windings shall be
limited to 80oC rise at maximum output.
3.6 Underfloor heating
Underfloor heating is to be provided to maintain the design temperature stated earlier in
this specification. The underfloor heating is to be cast into a concrete screed provided by
the Contractor.
The underfloor heating system is to be designed, supplied and installed by an underfloor
heating specialist company that is a member of the Underfloor Heating Manufacturers
Association (UHMA).
The manifold serving the underfloor heating system is to be a blending composite
manifold suitable for flow and return water temperatures from the boiler of 80/60 oC. The
manifold is to incorporate isolating valves, pumps, circuit flow rate adjusters and a full
by-pass valve to form a complete installation.
Upon completion the underfloor heating system is to be pressure tested and remain
under pressure whilst the screed is laid to ensure that any damage to the pipework is
identified immediately.
The underfloor heating installation is to be undertaken by Warmafloor GB Ltd or equal.
3.7 Pipework and Fittings
Pipework shall be installed in copper tubing to BS 1057:2006 with capillary and
compression fittings and joints to BS EN1257, to the general requirements of this
specification.
Capillary fittings shall be utilised in all service voids, shafts and ceilings. Compression
fittings shall be used for valves and for connection to sanitary fittings, plant and
equipment. All overflows, flushing pipes and discharge pipes to drain shall be installed
with compression fittings. Capillary joints shall be made using solder complying with BS
EN ISO 9353.
Capillary fittings shall be utilised in all service voids, shafts and ceilings. Compression
fittings shall be used for valves and for connection to plant and equipment. All overflows,
flushing pipes and discharge pipes to drain shall be installed with compression fittings.
Lead based solder shall NOT be used.
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3.8 Pipework Supports
Pipework shall be supported by two piece brass clips at spacings no greater than those
stated in the British Standard.
3.9 Valves
Isolating valves shall be full bore spherical ball valves, quarter turn with lever handles for
sizes 54mm and below. Ball valves shall have DZR, chrome plated body with PTFE
seats and stem seals. Valves shall be manufactured by Hattersley fig 100 or equal.
Double regulating valves shall be oblique pattern and have non rising spindle and setting
shall be by limitation of the spindle lift with pre-set value displayed on the hand wheel.
Valves shall have locking and marking facilities for the pre-setting.
Valves shall be as manufactured by Hattersley fig 1432.
In addition commissioning stations shall be provided on all branches of the heating
system to allow the installation to be fully balanced on completion of the installation.
Commissioing stations shall comprise a double regulating valve fitted with a metering
station Hattersly fig 2432.
Non-return valves shall be Hattersley Fig 47.
Drain cocks shall be Hattersley Fig 371 in occupied areas and Fig 81Hu in the plantroom
to enable draining of the system by hosepipe. Drain valves shall be fitted at all low
points.
Air bottles and vents shall be used throughout the system at all high points.
3.10 Pipeline Equipment
Expansion shall be accommodated by the natural flexibility of the pipework and devices
are not required.
Test points shall be Binder type with protective covers for both pressure and temperature
sensing.
3.11 Flushing and Chemical Treatment
Following hydraulic testing, the heating system shall be thoroughly flushed through to the
satisfaction of the Contract Administrator.
All control valves etc. shall be isolated and the flushing valves opened. Strainer baskets
shall be removed and all sediment run to waste.
The heating system shall be chemically treated with Fernox corrosion and scale
preventor or equal and approved. The chemicals shall be compatible with the component
materials of the system.
Commissioning and balancing may take place once the flushing and chemical treatment
is complete.
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3.12 Testing
The pipework systems shall be hydraulically tested to 7 bar for a period of 1 hour,
witnessed and certified by the Contract Administrator.
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4.0 Gas Service
4.1 Extent
A new gas meter will be provided in a new GRP meter enclosure. The meter and
enclosure will be provided by the local supply authority.
From the new meter, run an MDPE gas main buried under the entrance path to the
property, the gas main will be run in a common services trench which will include the
electricity supply, telephone supply and water main in part of the route. The new gas
main will enter the building at the plantroom and classroom toilets.
All buried gas pipework is to be provided with a marker tape to indicate the presence of
the gas main. The marker tape is to include a tracer wire to allow the location to be
identified using electronic survey equipment.
The gas main will adapt to steel outside the building and rise up to enter the building at
low level in each location. From the entry point the gas supply will run to serve the
boilers as identified.
The gas supply to the plantroom will supply the heating boiler and the gas fired water
heater.
The gas supply is to be provided with an emergency isolation valve at the point of entry
to the plantroom. The isolation valve is to be operated by either an emergency knock off
button located adjacent to the door to the plantroom or by heat detectors located above
the boiler and gas water heater.
Provide gas isolating valves to all items of equipment.
All necessary plant, equipment, pipework, pipework ancillaries, insulation, controls,
testing, purging, commissioning, supports and operating and maintenance manuals shall
be provided to form a complete installation.
4.2 Pipework and Fittings
Externally buried gas pipework shall be IGE approved, yellow medium density
polyethylene (MDPE) pipes and fittings for installation below ground, for working
pressures up to 4 bar and temperatures up to 40oC.
The below ground pipework is to be provided with a tracer tape to indicate the position of
the pipework to prevent accidental damage.
Joints on PE to PE shall be shall be electro-fusion or butt fusion type, branch saddles or
tapping tees shall be electro-fusion, flanged joints to mate with valves, etc. shall be
pupped butt fusion with galvanised MS backing rings drilled to BS4504 gaskets as
recommended by the manufacturer.
At the point of entry to the building the gas pipe shall adapt to heavy grade steel to BS
EN 10255:2004 1.0m from the building. The steel pipe shall rise from below ground
against the external wall with a Tee piece and purge point before entering the building
with a sleeve built into the wall. The steel pipe shall be fabricated and then painted with
two coats of good quality oxide paint and one coat of quality ‘gas’ ochre yellow gloss.
Steel pipework to be buried shall be completely wrapped in denso tape or equal,
Mechanical Specification – Crowdys Hill School
18
inclusive of adaptor flanges and flange bolts to the MDPE. The denso tape shall be
taken to a minimum 40mm above finished ground level.
Pipework above ground shall be installed in mild steel pipe to BSEN 10255:2004
medium grade supplied with screwed ends.
Screwed fittings shall be malleable cast iron beaded fittings manufactured to BS 1256
screwed to BS21 and suitable jointing materials to suit the pipe contents.
4.3 Pipework Supports
Pipework shall be supported by two piece brass clips at spacings no greater than those
stated in the British Standard.
4.4 Valves
Gas cocks shall be bronze taper plug with malleable iron handles as Hattersley Newman
Hender.
4.5 Painting
All exposed pipework in the building is to be finished in the relevant BS colour coding.
4.6 Pressure Test
The whole of the gas installation shall be pressure tested in accordance with the latest
regulations and codes of practice to twice the system working pressure.
On completion of the pressure test, the installation shall be purged in accordance with
BS CP 31 part 3 and the recommendations of “Purging procedures for Non-domestic gas
installations – British gas publication – report No IM/2”, Institution of Gas Engineers and
Managers (IGE/UP1 and 1a).
Mechanical Specification – Crowdys Hill School
19
5.0 Ventilation
5.1 Extent
Extract ventilation is to be provided to the toilet areas.
In the toilet areas, generally the extract fans are ceiling mounted with the extract duct
running through the ceiling void and discharging to outside via a grille mounted on the
underside of the fascia boards around the flat roofed blocks. In the hall block the fans
discharge to outside via grilles in the end gable wall of the building.
The disabled WCs are served by a wall mounted fan.
All toilet extract fans are operated by PIR detectors.
Extract ductwork shall be Galvanised sheet steel (GSS) ductwork fabricated to comply
with the recommendations of BS5720 and the Heating and Ventilating Contractors
Association specification DW144.
All necessary plant, equipment, ductwork, ductwork ancillaries, insulation, controls,
testing, flushing, commissioning, supports and operating and maintenance manuals shall
be provided to form a complete installation.
5.2 Extract fans
Supply and install a Lo Carbon fan with integral magnetronic shutter (IMC) and
removable grille as manufactured by
Vent Axia Ltd
Fleming Way
Crawley
West Sussex
RH10 9YX
The fan case and grille shall be made from ABS plastic and have an axial impeller. The
fan should be double insulated to meet IEE Wiring Regulations and meet the Building
Regulations Document F and the requirements of this specification.
The electronically controlled motor is to be fitted with long life ball bearings to provide an
expected 50,000 hour running life and a Standard Thermal Overload Protection (STOP).
The motor should be insulated to Class III (-25oC to +40oC) and is to conform to BS EN
60335-2-80.
Operation of the fan is to be provided by PIR presence detector with a 20 minute
(adjustable) overrun timer.
The extract fan is to be ceiling or wall mounted complete with all necessary mounting
and ductwork kits to form a complete installation.
5.3 Discharge grilles
Provide and install on the discharge from the toilet extract systems a wall or fascia
mounted grille.
Mechanical Specification – Crowdys Hill School
20
5.4 GSS Ductwork and Fittings
All ductwork systems shall be constructed from hot dipped galvanised steel to BSEN
10142 grade DX51D + Z coating type Z275. Ductwork shall be medium pressure class B
with minimum sheet thicknesses being in accordance with table 3 of DW144.
Ductwork fittings shall be constructed in accordance with DW144.
The ductwork installation shall satisfy the air leakage requirements of Table 1 of DW144
and shall be subject to 100% testing.
Sealants and gaskets used in the manufacture and installation of sheet metal ductwork
shall comply with section 8.2 of DW144.
5.5 Ductwork Support
All ductwork shall be adequately supported. Ductwork shall be supported within 600mm
of either side of ach 90o bend and not more than 600mm from the end of each run of
ductwork.
Where there is the possibility of noise or vibration, care shall be taken to isolate the duct
from the building.
Mechanical Specification – Crowdys Hill School
21
6.0 Fire Sprinkler System
7.1 General
A fire sprinkler system is to be designed and installed by a specialist sub-contractor.
Mechanical Specification – Crowdys Hill School
22
7.0 Thermal Insulation
7.1 Extent
The Contractor shall insulate all pipework not exposed to view to prevent excessive heat
loss.
7.2 General
Materials containing asbestos shall not be used.
All insulating material, unless specified as including an air gap shall be in close contact
with the surface to which it is applied and all joints shall be sealed after, ensuring that the
edges of sectional material where employed are in close contact with one another over
the entire insulated surface.
All insulating materials shall be “non-combustible” to BS 476: part 4, but may have a
surface finish not thicker than 0.8mm resulting in a class O “Spread of flame” to BS 476.
All insulation materials shall be non-corrosive to ferrous and non-ferrous metals. They
shall be water repellent, sterile, free from odour and offer no sustenance to vermin.
The materials shall be resistant to settlement and easily cut and fitted to shape during
installation and shall be resistant to damage or alternatively provided with suitable and
adequate protection.
Attention is drawn to the health hazards to personnel handling insulation materials.
Adequate precautions shall be taken against any hazard to health involved in the use of
any solvent, cleaner or material, in connection with the installation of the insulation.
Insulation which is incorrectly applied or damaged must be replaced. The specified
thickness shall be maintained and a neat and attractive finish shall be provided to suit
the location.
Insulation shall only be applied after satisfactory pressure and leakage tests have been
made and approved by the contract administrator.
7.3 Heating Pipework
Heating pipework shall be insulated with Armstrong Class O Armaflex AF insulation with
a natural black finish with a minimum thickness of 19mm.
7.4 Water Services
Water services pipework shall be insulated with Armstrong Class O Armaflex AF
insulation with a natural black finish with a minimum thickness of 19mm.
Mechanical Specification – Crowdys Hill School
23
8.0 Commissioning
8.1 Extent
The Contractor shall make full allowance for carrying out the balancing, testing and
putting to work all the installations described in this specification.
It is essential to ensure that the installations operate in conformity with the requirements
called for in this before practical completion is deemed to be achieved.
The Contract Administrator shall witness and sign off all testing and commissioning and
shall have access at all reasonable times to such parts of the works, and of the
Mechanical Sub-contractors works and specialist’s works, as may be necessary for the
purpose of inspecting, examining and testing the materials, workmanship and
performance of plant.
The Contractor shall give the Contract Administrator three days written notice of his
intention to carry out any test and shall have carried out all necessary adjustments prior
to commencing such test.
The Contractor shall allow for testing and commissioning the installation in sections in
order to conform to the Electrical Sub-contractor’s programme for power being available,
or other constraints.
The Contractor shall include for all labour, materials, stores, apparatus and properly
calibrated and certified instruments for carrying out testing and commissioning in
accordance with the specification.
The Contractor shall include balancing, testing and measuring of the installations
necessary to evaluate the design performance to be carried out in strict accordance with
the CIBSE Codes of Practice for commissioning The Codes of Practice are:
Series A Air distribution Systems, High and Low Velocity
Series B Boiler Plant
Series C Control Systems
Series W Water Distribution Systems
The above mentioned codes may be obtained from the Chartered Institute of Building
Services Engineers, Delta House, 222 Balham High Road, London. SW12 9BS
The instruments used during the commissioning and testing shall have been recalibrated by the manufacturer immediately prior to carrying out any measurement on
site.
Manufacturers of plant who put forward their own test figures for inclusion shall also
state, in writing, the type of instruments used to obtain the figures quoted.
8.2 Heating water Systems
The whole of the pipework installations shall be hydraulically tested in accordance with
section 5 of this specification.
Any equipment fitted, not suitable for the test pressure shall be adequately protected or
isolated from the system during the test.
Mechanical Specification – Crowdys Hill School
24
The Contractor shall include for balancing all systems, control valves etc. to ensure that
the circuit, plant or equipment is operating with the correct performance, temperature,
pressure and flow rate in accordance with the performance schedule and system design.
The boilers shall be commissioned by the manufacturers engineer to confirm that it has
been properly commissioned.
8.3 Water Services
The whole of the new water service pipework installation shall be flushed sterilised and
commissioned in accordance with section 2.3. The Contractor shall be responsible for
arranging for the Water Authority to witness tests, should they require to do so.
8.4 Ductwork Systems
The Contractor shall include for all air systems irrespective of pressure classification to
be commissioned and tested in accordance with CIBSE Code of Practice series A.
8.5 Control Systems
The control systems and associated motor control centres shall be commissioned by the
control specialist to CIBSE Code C.
8.6 Commissioning Data Sheets
Commissioning data sheets shall be produced by the Contractor during commissioning,
indicating the design conditions, site test readings and observations for all plant
equipment and systems.
Upon completion of final balancing and commissioning of the systems the Contractor
shall submit his test results in duplicate to the Contract Administrator for approval, prior
to witnessing.
The site test measurements shall not be approved by the Contract Administrator until
they concur with the design conditions.
Upon approval by the Contract Administrator of the test results, and observations that
the systems are fully commissioned, the installation can only then be considered for
acceptance as achieving “Practical Completion” ready for handover.
The approved Commissioning Data Sheet shall then be incorporated into the Operating
and Maintenance Instructions by the Contractor.
Mechanical Specification – Crowdys Hill School
25
9.0 Mechanical Services Pricing Breakdown
Description
Water Services
Hall Block
Classroom Block 1 and link
Classroom Block 2 and link
Heating
Hall Block
Classroom Block 1 and link
Classroom Block 2 and link
Gas Service
Hall Block
Classroom Block 1 and link
Classroom Block 2 and link
Ventilation
Hall Block
Classroom Block 1 and link
Classroom Block 2 and link
Fire Sprinkler System
Hall Block
Classroom Block 1 and link
Classroom Block 2 and link
Thermal Insulation
Hall Block
Classroom Block 1 and link
Classroom Block 2 and link
Commissioning
Hall Block
Classroom Block 1 and link
Classroom Block 2 and link
Price
£
£
£
----------------£
£
£
----------------£
£
£
----------------£
£
£
----------------£
£
£
----------------£
£
£
----------------£
£
£
-----------------
Provisional Sums
Contingency
TOTAL
Mechanical Specification – Crowdys Hill School
£2000.00
£
-----------------
26