Specification document for Adveco Totem mCHP

1.0 PERFORMANCE OBJECTIVES..........................................................................................................................22.0 DESIGN PARAMETERS......................................................................................................................................22.1 RELEVANT STANDARDS....................................................................................................................................22.2 CHP DESIGN STANDARDS................................................................................................................................22.3 ENGINE EMISSIONS...........................................................................................................................................32.4 OPERATING PARAMETERS...............................................................................................................................33.0 SYSTEM DESCRIPTION......................................................................................................................................34.0 APPLIANCE SPECIFICATION............................................................................................................................44.1 ENGINE................................................................................................................................................................44.1.1 LUBRICATING SYSTEM......................................................................................................................................44.1.2 STARTING SYSTEM............................................................................................................................................54.1.3 ENGINE CONTROL UNIT....................................................................................................................................54.1.4 CATALYTIC CONVERTER...................................................................................................................................54.1.5 IGNITION SYSTEM..............................................................................................................................................54.1.6 AIR INLET............................................................................................................................................................54.1.7 GAS SUPPLY TRAIN...........................................................................................................................................54.2 HEAT RECOVERY SYSTEM...............................................................................................................................54.2.1 PRIMARY COOLING SYSTEM............................................................................................................................54.2.2 PRIMARY HEAT EXCHANGER...........................................................................................................................64.2.3 CONDENSING EXHAUST GAS HEAT EXCHANGER.........................................................................................64.3 ELECTRICAL GENERATION...............................................................................................................................64.3.1 ASYNCHRONOUS GENERATOR........................................................................................................................64.3.2 ELECTRICAL AND CONTROL WIRING..............................................................................................................64.4 FLUE SYSTEM.....................................................................................................................................................64.4.1 GENERAL............................................................................................................................................................64.4.2 FLUE MATERIAL..................................................................................................................................................74.4.3 APPLIANCE CONNECTION.................................................................................................................................74.4.4 FLUE SIZE...........................................................................................................................................................74.5 INTEGRATED CONTROL PANEL........................................................................................................................74.5.1 POWER CONTROLS...........................................................................................................................................74.5.2 OPERATIONAL CONTROLS...............................................................................................................................74.5.3 DIGITAL INTERFACE..........................................................................................................................................74.6 CHP ACOUSTIC ENCLOSURE...........................................................................................................................84.6.1 ENCLOSURE DIMENSIONS................................................................................................................................84.6.2 SERVICE AND MAINTENANCE..........................................................................................................................84.6.3 ACOUSTIC SHIELDING.......................................................................................................................................84.6.4 NOISE TRANSMISSION......................................................................................................................................85.0 CONTROL REQUIREMENTS..............................................................................................................................86.0 SCOPE OF WORKS............................................................................................................................................97.0 CHP APPLIANCE INSTALLATION.....................................................................................................................97.1 PLANT ROOM......................................................................................................................................................97.1.1 LOCATION...........................................................................................................................................................97.1.2 ACOUSTIC SHIELDING.......................................................................................................................................97.1.3 PREVENTION OF CONTAMINATION................................................................................................................107.1.4 VENTILATION....................................................................................................................................................107.2 MECHANICAL INSTALLATION..........................................................................................................................107.2.1 HEAT EXCHANGERS AND FITTINGS..............................................................................................................107.2.2 PIPEWORK........................................................................................................................................................107.2.3 THERMAL INSULATION....................................................................................................................................107.2.4 NATURAL GAS..................................................................................................................................................117.2.5 SILENCER(S) AND EXHAUST SYSTEM...........................................................................................................117.2.6 CONDENSATE DRAIN.......................................................................................................................................117.2.7 CLEANING AND FLUSHING..............................................................................................................................117.3 ELECTRICAL INSTALLATION...........................................................................................................................127.3.1 GENERAL..........................................................................................................................................................127.3.2 CHP INTERFACE PROTECTION CONTROL PANEL........................................................................................128.0 CHP UNIT CONTROL & OPERATION..............................................................................................................128.1 GENERAL..........................................................................................................................................................128.2 START PROCEDURES......................................................................................................................................128.3 RUN PROCEDURE............................................................................................................................................138.4 STOP PROCEDURES........................................................................................................................................138.5 CHP UNIT PROTECTION..................................................................................................................................138.6 CHP SYSTEM MONITORING............................................................................................................................149.0 TESTING AND COMMISSIONING.....................................................................................................................1410.0 OPERATION & MAINTENANCE MANUALS.....................................................................................................14

1.0 PERFORMANCE OBJECTIVES

The primary objective is to provide a Combined Heat & Power system whose heat and electrical outputs shall feed the site's heating and electricity distribution systems. The CHP system is designed to provide [INSERT PROJECT NAME] with both heat and electricity, with the object of long term savings in energy costs. Electricity will not be exported from the site during periods of low on site electricity usage therefore accurate selection will be required.

The CHP engine system shall be “heat lead” but shall contain the facility to be electrically lead by modulating the engine when generated capacity exceeds site demand. The CHP system shall consist of [1] [2] [3] [4] [DELETE AS APPROPRIATE] Adveco Totem CHP engine(s) to allow for maximum flexibility and overall efficiency

Ensure the system is capable of operating for a minimum of [INSERT RUN TIME] hours per day except when shut down for maintenance or repair. The CHP unit is not required to operate as an emergency generator.

2.0 DESIGN PARAMETERS

The CHP system design shall meet the minimum requirements of the following publications:

2.1 RELEVANT STANDARDS

Comply fully with the edition (including amendments) of each of the following, current at the time oftender: -

BS 7671 Requirements for electrical installations. The IEE Wiring Regulations

ENA ER G59/3 Recommendations for the connection of embedded generating plant to the Distribution Network Owner’s systems

ENA ER G83/2 Recommendations for the connection of embedded generating plant to the Distribution Network Owner’s systems

IEC 34-1 General requirements for rotating electrical machines

IGE/UP/2 Installation pipework on industrial and commercial premises

IGE/UP/3 Gas fuelled spark ignition and dual fuel engines

IGE/UP/10 Installation of Flued Appliances

Local Authority environmental requirements and planning conditions.

The Electricity Supply Regulations

2.2 CHP DESIGN STANDARDS

The CHP shall be designed and independently certified to the following standards:

EN 50465 European product standard for combined heating power systems using gas fuel.

IEC 61000-6-2 Electromagnetic compatibility (EMC) - Part 6-2: Generic standards - Immunity standard for industrial environments

IEC 61000-6-3 Electromagnetic compatibility (EMC) - Part 6-3: Generic standards - Emission standard for residential, commercial and light-industrial environments

EN 12601 Reciprocating internal combustion engine driven generating sets. Safety

EN 60204-1 Safety of machinery. Electrical equipment of machines. General requirements

EN ISO 13849-1 Safety of machinery. Safety-related parts of control systems. General principles for design

2009/142/EC Gas Appliance Directive

92/42/EEC Boiler Efficiency Directive

2014/30/EU Electromagnetic Compatibility (EMC) Directive

2006/42/EC Machinery Directive

2.3 ENGINE EMISSIONS

To reduce local levels of air pollution, the engine emissions shall not exceed the following values:

NOX Emissions – 0% O2 7.5 mg/kWh Gas InputNOX Emissions – 0% O2 8.8 mg/Nm3

NOX Emissions – 5% O2 6.7 mg/Nm3

CO Emissions – 0% O2 8.6 mg/Nm3

Emissions data shall be independently verified by a notified body and a test report shall be available for inspection by the engineer on request.

2.4 OPERATING PARAMETERS

The design is based on the following parameters:

Ref Description Unit Unit Unit1 Minimum CHP unit net electrical output at maximum continuous

rating (MCR) and at 0.96 power factor10 kW 20 kW 25 kW

2 Minimum CHP unit heat output to LTHW at maximum output (35°C return temperature)

25.0 kW 48.5 kW 57.6 kW

3 Minimum CHP unit heat output to LTHW at minimum output (35°C return temperature)

16.4 kW 30.9 kW 30.9 kW

4 Nominal CHP unit gas consumption. Gas supplier to confirm calorific value of gas supplied at time of commissioning.

3.29 m3/hr 6.27 m3/hr 7.56 m3/hr

5 Minimum net CHP electrical export efficiency (excluding consumption of CHP controls and primary pumps)

29.6% 31.2% 32.5%

6 Minimum net CHP unit overall efficiencies at maximum output (35°C return temperature)

104.3% 106.8% 107.4%

7 Minimum net CHP unit overall efficiencies at minimum output (35°C return temperature)

101.5% 105.0% 105.0%

8 Minimum gas pressure measured at the CHP unit inlet (Vendor's specification)

17.0 mbar 17.0 mbar 17.0 mbar

9 Minimum return water temperature 11°C 11°C 11°C10 Maximum return water temperature 72°C 72°C 72°C11 Maximum working pressure 10.0 bar 10.0 bar 10.0 bar12 Heat load pipe connections Rp 1 ¼” Rp 1 ¼” Rp 1 ¼”13 Nominal heat load flow rate 2500 l/hr 4000 l/hr 5000 l/hr14 LTHW Temperature rise 8.6 K 10.4 K 9.9 K15 CHP operating noise level at 1m (maximum) 56.7 dB(A) 61.1 dB(A) 61.1 dB(A)

3.0 SYSTEM DESCRIPTION

The CHP unit shall be constructed and rated for continuous operation, to provide an electrical output and thermal output in accordance with the schedule.

The CHP shall include a natural gas fuelled, water-cooled, 4 stroke, reciprocating type, spark ignition engine of proven design and from a reputable manufacturer with proven experience in gas engine and CHP applications. The engine design shall be tested for compliance with European emissions standard stage ‘Euro 6’ to ensure that the engine exhaust gases comply with current emissions regulations. The engine shall achieve continuous engine power output with an external ambient air temperature of 25°C, an air pressure of 101.3 kPa and a relative humidity of 60%.

Heat recovery shall be provided by a condensing exhaust-gas heat exchanger and engine cooling system plate heat exchanger located within the main appliance casing. The heat recovery system shall be installed and pressure tested as part of appliance manufacture.

To reduce engine wear, once ignition has been proven, the CHP shall operate at a low engine speed until such a time as the engine and associated components have reached the optimum working temperature. When the optimum engine temperature has been reached, the microprocessor control will increase engine speed and command the generator controls to synchronise.

During normal operation, the CHP return temperatures shall be monitored by the internal microprocessor control system and the CHP shall operate until the return temperature reaches the CHP ‘T-off’ temperature. To reduce excessive cycling and wear of the internal combustion engine, once the CHP stops the engine shall be shut down until the LTHW return temperature drops to the ‘T-On’ temperature. The volume of the buffer vessel and the value of ‘T-On’ shall be configured to promote operational cycle times in excess of 1 hour.

To extend operational hours and reduce engine wear due to cycling, the CHP control system shall be designed to reduce engine power output from 100% to 85% when the LTHW return temperature is within 5 K of the CHP’s ‘T-Off’ value. The CHP shall also contain the controls to allow the modulation of engine power output in relation to site electrical demand where electrical load has been shown to be less than the maximum output of the appliance.

An electrical control system shall act as interface protection between the CHP and the DNO supply. The interface protection shall include a G59/G83 compliant relay that will disconnect the CHP in the event of any deviation between the generated electricity and the DNO supplied electricity. As the CHP plant is not required to operate as a standby generator, the interface protection system shall automatically disconnect the CHP from the electrical system in the event of a failure of the DNO supply.

4.0 APPLIANCE SPECIFICATION

The CHP appliance shall meet the following specification:

4.1 ENGINE

The power source shall be an internal combustion engine with the following features:

4.1.1 LUBRICATING SYSTEM

The engine lubricating system shall be designed to automatically discard used engine oil after a period of 500 hours of engine operation. An automatic top up system shall then replenish the engine oil to the required level. The CHP shall include – within the appliance casing – reservoirs

for the storage of clean and used engine oil. The reservoirs shall be of sufficient capacity to meet the manufacturer’s recommended engine oil volume and recommended service interval.

4.1.2 STARTING SYSTEM

The engine shall be equipped with a 12V electric starter motor, starter solenoid and auxiliary start relays. A maintenance free 12V lead acid battery shall be contained within a ventilated compartment with an overheat monitoring system. All cables and clamps for connection to the starter motor shall be integral to the appliance wiring.

4.1.3 ENGINE CONTROL UNIT

An automotive electronic-type engine speed and load governor shall be used to increase the response frequency and give greater control over engine emissions. The Engine Control Unit (ECU) shall be connected to 2 lambda sensors, located on the engine exhaust manifold and downstream of the catalytic converter to allow real-time monitoring of exhaust gas ratios and adjustment of fuel/air mixture.

The ECU shall be located where it is protected from heat and vibration.

4.1.4 CATALYTIC CONVERTER

To reduce exhaust gas emissions, the CHP shall include within the appliance casing a ceramic type catalytic converter designed to operate under the high exhaust gas temperatures associated with the combustion of natural gas.

4.1.5 IGNITION SYSTEM

The engine shall be equipped with an electronic ignition system, ignition coil(s), ignition leads and suitable spark plugs with a life expectancy at least exceeding the maintenance interval. All components shall be situated to prevent damage from engine heat.

4.1.6 AIR INLET

A dry type air cleaner with easily removable filter element and restriction indicator shall be included as part of the engine package.

4.1.7 GAS SUPPLY TRAIN

The CHP gas supply train shall comply with current regulations and include a manual shutoff valve, 200-micron gas filter, safety shut-off valve, gas pressure sensor and low pressure alarm.

The CHP unit shall be capable of operating providing the gas pressure – measured at the gas connection point – is at least that specified in section 2.3.

4.2 HEAT RECOVERY SYSTEM

The CHP heat recovery system shall include the following features:

4.2.1 PRIMARY COOLING SYSTEM

The primary cooling system shall be designed to recover heat from the generator, internal combustion engine, engine oil [DELETE FOR 10 kW MODEL] and high-temperature exhaust gas heat exchanger.

The CHP shall regulate the engine water circuit temperature by a mechanically operated three-way thermostatic valve, to enable the engine to achieve its operating temperature in the shortest possible time and avoid any influence in temperature by a widely varying secondary water temperature.

The CHP shall incorporate within the appliance casing a sealed closed circuit system and include a glycol anti-freeze fill, electrically driven circulation pump, expansion tank, fill and drain connections, overpressure protection, water level sensor and water temperature sensor.

4.2.2 PRIMARY HEAT EXCHANGER

Heat exchange from the primary cooling system to the LTHW system shall be via an integral plate heat exchanger. The heat exchanger shall be selected by the manufacturer to ensure that heat transfer is sufficient under all operating conditions and installed within the appliance acoustic casing.

4.2.3 CONDENSING EXHAUST GAS HEAT EXCHANGER

The CHP shall include – within the appliance casing – a shell and tube type exhaust gas heat exchanger incorporated within the LTHW circuit and located within the engine exhaust system downstream of the catalytic converter.

The heat exchanger shall be sizer to lower the exhaust gas temperature to within 10 K of the LTHW return temperature. The heat exchanger shall be designed to operate in condensing mode when the LTHW return temperature is low enough.

The heat exchanger shall be installed with a fall towards the downstream connection to allow any condensate formed to freely drain and the condensate drain shall be fitted with a noise muffling water trap.

The heat exchanger shall be constructed from AISI 316 grade stainless steel.

4.3 ELECTRICAL GENERATION

The electrical generation system shall consist of the following features:

4.3.1 ASYNCHRONOUS GENERATOR

The CHP shall be equipped with an induction generator that is directly driven by the engine. The generator shall be a brushless, asynchronous, 2-bearing type, suitable for 400V, 50Hz, 3ph operation.

4.3.2 ELECTRICAL AND CONTROL WIRING

The CHP shall include all electrical components and cabling required for normal operation. The manufacturer shall ensure components are suitably heat resistant and electrically shielded where necessary. All wiring shall be installed to avoid contact with hot surfaces, securely clipped and run in positions which do not hinder access or where the wiring can be easily damaged. Wiring terminations shall be provided with numbered terminal strips that correspond to the unit wiring diagram.

All wiring must comply with BS 7671.

4.4 FLUE SYSTEM

The CHP flue system shall meet the following requirements:

4.4.1 GENERAL

The CHP shall be designed to operate with an exhaust temperature no greater than 100°C.

4.4.2 FLUE MATERIAL

The CHP shall be fitted with a flue system CE marked to EN14471 T120 H1. Where the CHP is to be installed with a flue other than the manufacturer’s recommended system, an equivalent level of construction shall be maintained.

4.4.3 APPLIANCE CONNECTION

The appliance manufacturer’s flue connection kit shall be used in all circumstances and includes the necessary components to connect to the appliance, a water trap for condensate drainage, a flexible connection to reduce vibration, an exhaust gas silencer, and an adapter for connection to the flue system.

4.4.4 FLUE SIZE

The CHP shall be connected to a flue system with an outside diameter of at least 110 mm.

4.5 INTEGRATED CONTROL PANEL

The CHP shall be designed to include an integrated control panel. The control panel shall include necessary control systems for synchronisation of the induction generator to Distribution Network Operator (DNO) supply as well as the following features:

4.5.1 POWER CONTROLS

The control panel shall include following power controls:

A generator synchronisation contactor. A charger for the engine starter battery. A contactor for the motor starter. A contactor for the engine water circulation pump. A contactor for the appliance cooling fan. A contactor for the secondary water circulation pump Fuses, auxiliary power relays, terminal strips and current transformers as necessary for

automatic control and protection.

All power connections shall be shrouded against accidental contact when live.

All minor wiring in shall be routed in slotted ducting. Terminate small wiring in shrouded terminal strips numbered as in the contract drawings.

4.5.2 OPERATIONAL CONTROLS

The control panel shall include following operational control connections:

Safety interlock connection. Thermostat enable connection. BMS enable connection. Generator output status connection. Engine alarm status connection. Engine service notification.

4.5.3 DIGITAL INTERFACE

The CHP shall be equipped with a touchscreen interface and a microprocessor based control system, its function to include:

Manual start and stop of the CHP system. Automatic start and stop of the CHP engine. Temperature monitoring. Safety system monitoring and protection. Data processing and storage; Communication to remote computers.

Remote communication is to be via an integrated GRPS module that will allow real-time monitoring of critical parameters.

4.6 CHP ACOUSTIC ENCLOSURE

The components that make up the CHP unit shall be assembled within an acoustic enclosure that meets the following requirements:

4.6.1 ENCLOSURE DIMENSIONS

Unless access is shown on the contract drawings to be sufficient, the CHP shall be sized to allow the appliance to pass through an 850mm accessible doorway and have a maximum height (including service clearance) of less than 2300mm

4.6.2 SERVICE AND MAINTENANCE

The acoustic enclosure shall be fully removable to allow access to all internal components for the purpose of service and maintenance.

4.6.3 ACOUSTIC SHIELDING

The acoustic enclosure shall ensure that the noise levels stated in Section 2.4 are not exceeded.

4.6.4 NOISE TRANSMISSION

The engine and generation sections of the CHP unit shall be installed on a suitably rigid steel base frame, through resilient mounts to limit vibration transmission. Additional resilient mounts shall be provided with the CHP to be used between the steel frame and building structure to further reduce the transmission of vibration.

5.0 CONTROL REQUIREMENTS

DHW PRIORITY – [DELETE AS APPROPRIATE ]

The heat rejected by the CHP unit is designed to be used by the building heating system to meet the building HWS requirement. The CHP shall feed – via a buffer vessel – an indirect ‘pre-heat’ vessel to ensure optimum efficiency and operational hours. The pre-heated water shall be piped in to secondary water afterheaters which will only function if the pre-heated feed is below the required stored water temperature.

Circulation between the CHP unit and buffer vessel is to be managed by the CHP control system and the secondary pump should be constantly available to ensure maximum run time of the

system. There shall be no temperature controls between the CHP and buffer vessel other than an over-temperature protection system.

Temperature controls shall be installed within the buffer vessel and pre-heat vessel and the HWS charging pump activated when the temperature within the buffer vessel exceeds the temperature in the pre-heat vessel by 6 K and the temperature of the stored water within the pre-heat vessel is below the required value.

Where additional heating circuits exist, a heating pump shall be installed and shall operate when the pre-heat vessel meets its required temperature and when the temperature recorded within the heating return pipework is 6 K below the value measured within the buffer vessel.

HEATING PRIORITY – [DELETE AS APPROPRIATE]

The CHP shall be connected to the LTHW system in a configuration that ensures the coolest water is fed in to the buffer vessel and CHP. It is generally expected that the coolest point will be on the system side of any low-loss header. The flow from the thermal store shall be fed in to the return to the LTHW boilers or low-loss header enabling the CHP to act as a pre-heat and reduce the overall load on the LTHW boilers.

Where a combined CHP and heating thermal store is used, the CHP connections shall be below those of the heating boiler to ensure the optimum operation of the CHP unit.

When the heating system return temperature rises above the CHP ‘T-Off’ temperature setpoint, as measured by the CHP unit's own temperature detector, the CHP shall shut down until the return temperature drops below the CHP ‘T-On’ temperature setpoint. To prevent wastage of energy, thermal discharge systems such as heat dumps shall not be installed within the LTHW system.

6.0 SCOPE OF WORKS

The scope of the works for the CHP installation is as follows:

1. CHP packaged unit(s), rated as specified in schedule [AMEND AS APPROPRIATE]2. All necessary pipework, fittings, pumps and controls3. Associated electrical equipment including control panels, wiring, cable ways4. Flue and silencer system.5. Ventilation ductwork & fans or louvres.6. Heat load and gas pipe work connections7. Testing, commissioning, demonstration and provision of operating and maintenance

manuals. The CHP plant shall achieve the output criteria detailed in Section 2.0

7.0 CHP APPLIANCE INSTALLATION

7.1 PLANT ROOM

7.1.1 LOCATION

Install the CHP in the locations indicated on the contract drawings. Locate the CHP on a flat level floor or plinth which is structurally capable of supporting

the weight of the unit and equipment attached to it. Allow sufficient space around the unit for maintenance and parts replacements. Provide

the following minimum clearances:o 800 mm to the left, right and front.o 600 mm to the rear.

o 800mm above.

7.1.2 ACOUSTIC SHIELDING

The CHP appliance casing shall be acoustically shielded and constructed to give a maximum noise level as specified in Section 2.4, at a distance of 1.0 m. Unless specifically required, no additional acoustic protection shall be installed.

Flexible connections shall be used on all external electrical and mechanical connections made to the unit including exhaust pipe work, water/cooling systems and fuel systems to permit free movement of the CHP unit on its resilient mounts.

7.1.3 PREVENTION OF CONTAMINATION

Provide drip tray(s) under every part of the CHP unit where drips of fluid may possibly occur. Ensure all provided trays can be easily removable for emptying.

7.1.4 VENTILATION

Provide the plant area with ventilation louvres or mechanical ventilation at high and low level to supply an adequate volume of air for combustion and for cooling the CHP unit at full output. The ventilation requirement for the CHP shall be calculated in accordance with the manufacturer’s requirements and shall be in addition to the requirements of all other gas-fired plant.

Ensure that any mechanical ventilation system is interlocked and any gas firing equipment is shut down on air flow failure.

7.2 MECHANICAL INSTALLATION

7.2.1 HEAT EXCHANGERS AND FITTINGS

The CHP shall be supplied with all necessary heat exchangers and pipework within the appliance casing.

7.2.2 PIPEWORK

Pipework between the CHP and thermal storage vessel shall be selected to ensure that the minimum flowrate detailed in Section 2.3 can be maintained.

Provide a pipe work system with a minimum working pressure of 1.0 bar including an expansion vessel, safety valve and strainer for each CHP unit circuit. Provide a mesh strainer and dirt pocket in the inlet to the CHP.

Install flexible sections between the CHP and circulation pipework to reduce vibration transmission.

Isolating valves, circulating pumps, and safety valves shall be installed where appropriate. Automatic air vents shall be installed at pipework high points where appropriate.

Provide suitably sized isolating valves and connections to the thermal storage system.

Install an overheat thermostat in the CHP flow pipework for over-temperature protection.

7.2.3 THERMAL INSULATION

Thermally insulate all interconnecting pipe work in accordance with the [AMEND AS APPROPRIATE] sections of this specification.

7.2.4 NATURAL GAS

Ensure that the whole of the gas installation complies with the Institution of Gas Engineers and Managers publications IGE/UP/2, IGE/UP/3, and with the standards prescribed in the [AMEND AS APPROPRIATE] sections of this specification.

Arrange with the gas supplier and gas distribution company to supply the appliance with gas at the pressure and flow rates specified in Section 2.4.

Provide gas pipe work, including all valves and fittings which are sized so that the gas pressure and flow rate available at the CHP unit comply with the values specified in Section 2.4 when all gas fired equipment on site is operational, including transient pressure drops when burners fire.

Provide gas pressure test points and purge points adjacent to the gas supply connection to the CHP unit and at other positions to be agreed with the engineer. Allow for up to four test points.

Provide a manual isolation valve in the site pipe work adjacent to the CHP unit gas connection. The valve should be located upstream of the mandatory flexible gas connection.

7.2.5 SILENCER(S) AND EXHAUST SYSTEM

Ensure that the CHP unit exhaust system complies with Institution of Gas Engineers and Managers publication IGE/UP/3 and local Environmental Health Department requirements (engineer to specify particular requirements).

Provide stainless steel resonance and absorption type exhaust silencers to comply with the unit and site noise control requirements.

Provide a flue system complying with Section 4.4. Make the exhaust flue as short as possible consistent with compliance with Environmental Health Department requirements. Preference should, where possible, be given to vertical termination and where this is not feasible, consideration should be given to noise levels adjacent to the terminal location. Additional silencers should be used where necessary.

Do not combine the CHP unit exhaust system with those of other plant unless approval from the CHP manufacturer is received and the flue system is designed by a flue system specialist.

Support the silencer(s) and exhaust system with adequate hangers and brackets. Protect the flue within the building from contact with any flammable materials. Provide an efficient weathering collar where the flue passes through any roof or external wall. Suitably terminate the flue to minimise the risk of water ingress, or blockage by birds or other foreign matter.

Provide adequate condensation water traps with drains, made from polypropylene or other suitable material and connected with suitable terminations to the site drains. Install exhaust system components so that condensate is reliably collected and prevented from running back into the engine.

7.2.6 CONDENSATE DRAIN

A condensate drain pipe and condensate water trap made from polypropylene plastic with a temperature rating in excess of 120°C shall be provided and discharged to a suitable termination point.

7.2.7 CLEANING AND FLUSHING

Ensure all CHP pipework and fittings are chemically cleaned and flushed through to the same standard as the building heating system, as described in the [AMEND AS APPROPRIATE] sections of this specification.

7.3 ELECTRICAL INSTALLATION

7.3.1 GENERAL

Provide electrical power and control wiring systems which comply with BS 7671, as shown on the contract drawings, and as specified elsewhere in this specification, as follows:

1. A suitably sized lockable 6 pole isolator should be installed to ensure isolation of main and auxiliary supplies to the appliance. The isolator should be mounted on the wall adjacent to the CHP Interface Protection Panel location, but clear of the panel door when open.

2. 3-core XLPE/SWA/LSF cable connection between the CHP control panel and interface protection panel and between the interface protection panel and the site LV distribution connection point, via a lockable isolator

3. A separate CHP unit protective earth cable which is not connected to the CHP unit neutral

4. BMS interface wiring to identified terminals in the CHP control panel and interface protection panel

5. Provide heat resistant electrical components and cabling materials. Install the wiring to avoid contact with hot surfaces, securely clipped and run in positions, which do not hinder access or where they can be easily damaged.

7.3.2 CHP INTERFACE PROTECTION CONTROL PANEL

Provide a CHP interface protection control panel for each CHP comprising a sheet steel enclosure, with lockable front access door, protected to IP54 and finished and painted in the maker's standard colour. Provide a prominent notice to warn of the danger of opening the panel door without isolating supplies.

A suitably sized 4 pole isolator should be installed between the electrical distribution panel and the CHP interface protection panel. The isolator should be mounted on the wall adjacent to the CHP Interface Protection Panel location, but clear of the panel door when open.

Ensure that the control panel contains an interface protection relay that complies with the requirements of the Distribution Network Operator.

8.0 CHP UNIT CONTROL & OPERATION

8.1 GENERAL

Ensure that the CHP system controls and protection comply with ENA publications G59/3 or G83/2, together with the requirements of the local electricity distribution company.

8.2 START PROCEDURES

The CHP shall start automatically provided:

All safety circuit contacts are in a ‘closed circuit’ condition. All external control contacts are in a ‘closed circuit’ condition.

The microprocessor based time control system (if activated) requires operation. A temperature at the inlet to the appliance is below the programmed value.

The system shall attempt to start three times with an automatic report to the remote monitoring system main computer and fault indication on the unit display panel should the third attempt fail.

To reduce engine wear, once ignition has been proven, the CHP shall operate at a low engine speed until such a time as the engine and associated components have reached the optimum working temperature. When the optimum engine temperature has been reached, the microprocessor control will increase engine speed and command the generator controls to synchronise.

8.3 RUN PROCEDURE

During normal operation, the CHP return temperatures shall be monitored by the internal microprocessor control system and the CHP shall operate until the return temperature reaches the CHP ‘T-off’ temperature. To reduce excessive cycling and wear of the internal combustion engine, once the CHP stops the engine shall be shut down until the LTHW return temperature drops to the ‘T-On’ temperature. The volume of the buffer vessel and the value of ‘T-On’ shall be configured to promote operational cycle times in excess of 1 hour.

To extend operational hours and reduce engine wear due to cycling, the CHP control system shall be designed to reduce engine power output from 100% to 85% when the LTHW return temperature is within 5 K of the CHP’s ‘T-Off’ value. The CHP shall also contain the controls to allow the modulation of engine power output in relation to site electrical demand where electrical load has been shown to be less than the maximum output of the appliance.

8.4 STOP PROCEDURES

The unit shall stop if there is:

An external stop command or A temperature stop command The microprocessor time control period expires (if activated)

When commanded to stop, the machine shall reduce the unit output to 50% load in a controlled manner and then open the generator contactor and allow the unit to run at idle speed until cool.

When the emergency stop button is depressed or if there is a failure, the CHP shall stop immediately and report the reason for the uncontrolled stop to the remote monitoring system main computer and communicate the fault on the unit display panel.

In the case of mains fluctuations beyond the prescribed voltage and frequency limits the interface protection shall immediately disconnect the electrical supply from the CHP by opening the connection contactor within the interface protection enclosure. The CHP shall open its synchonisation contactor within 5 seconds preventing reconnection to the DNO supply and allowing the interface protection control system to reset. The CHP shall carry out its standard shut down procedure and shall not restart until the cause of the intervention has been investigated.

If a failure of the DNO supply is detected, the interface protection system shall open the connection control contact and cause an immediate shut down of the CHP unit. The CHP shall remain stopped until the unit is manually reset by a push-button located on the CHP control panel.

8.5 CHP UNIT PROTECTION

Incorporate the following protection into the CHP unit control system:

Electricity mains:

Voltage too high/low Frequency too high/low Phase failure

Generator:

Voltage too high/low Frequency too high/low Current asymmetry Thermal overload Short circuit Reverse power

Engine:

Lubrication oil temperature too high Lubrication oil pressure too low Lubrication oil level in sump too low Engine water level too low Engine water temperature too high External water in/out temperature too high Exhaust gas temperature too high Acoustic enclosure temperature too high Gas pressure too high/low Under/over speed~ start failure Starter battery voltage too high/low (warning)

8.6 CHP SYSTEM MONITORING

Provide equipment to enable a full energy balance of the CHP unit to be measured and recorded:

Gas consumption meter Heat meter (by Sontex or equal)

Provide a web-based interface to monitor system parameters and give a means of displaying and setting user adjustable parameters including:

Setting of time & date, Start & stop parameters Reset of non-critical error conditions.

Provide the means to transmit operating and fault data to the CHP unit supplier’s service centre via a GPRS modem system.

9.0 TESTING AND COMMISSIONING

The mechanical and electrical systems shall be commissioned by the appliance manufacturer or their approved representative in accordance with the manufacturer’s approved procedures.

10.0 OPERATION & MAINTENANCE MANUALS

Provide two copies of the operation and maintenance manual.

Include all necessary operating instructions, warnings and advice with regard to the CHP unit, controls, switchgear and all ancillary equipment, including the following details:

1. CHP unit description and specification2. Operating instructions3. Component data sheets4. Commissioning method statement5. Maintenance instructions6. Fault finding guidance7. Schematic diagrams, circuit diagrams and general arrangement drawings8. Personnel and equipment safety warnings.