Post on 06-Feb-2018
Energy management
systems control panel
construction
Standard control specification
Users guide to Allen Martin heating
controls
Resources directorate
Energy management systems control panel construction
Standard control specification
2
Issue/
Revision No
Date Originator Purpose for Issue/
Nature of Change
0 05/0//05 R C Smith First issue
A 07/08/07 T N Thomas Regular Updates
B 14/06/10 T N THOMAS Regular Updates
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GENERAL DETAILS
Preamble
It is intended that this specification shall be read in conjunction with the Standard Technical Specification (ELECTRICAL INSTALLATION SERVICES)
and the Standard Technical Specification (MECHANICAL INSTALLATION SERVICES).
Certain sections of this specification may not relate to the drawings
supplied and accordingly should be disregarded.
Regulations
The installation shall be designed, installed, tested and commissioned in accordance with:
� The Health and Safety at Work Act together with all relevant
approved Codes of Practice and Memorandum of Guidance
� The most recent issue of BS 7671 together with all relevant
approved Codes of Practice and Guidance Notes
� The latest requirements of the Building Regulations
� The Electricity at Work Regulations together with all relevant
approved Codes of Practice and Memorandum of Guidance
� The Electricity Safety, Quality and Continuity Regulations
� Construction (Design and Management) Regulations
� Control of Substances Hazardous to Health – COSHH
� The Control of Asbestos Regulations 2006 including future
amendments and editions
The above shall not be seen as definite list of relevant standards and
regulations and, unless stated otherwise, the whole of the works shall comply with the requirements of all relevant British Standards and
European Harmonised standards and documents pertinent to the works. Relevant standards and regulations shall be those that are in force three
months prior to the return of tender or commencement of work unless stated otherwise in the particular specification documents.
Definitions
For the purpose of this document, terms and definitions shall be as those of the most recent edition of BS 7671 Part 2.
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British Standards
Where a British Standard or Code of Practice issued by the British Standards Institute is current at the date of tender and appropriate to the
case, the contract shall require that goods, materials and works shall be in conformity.
General Operating Conditions
This specification is written as general guidance to the methods of panel manufacture.
It is not intended as a definitive method, as all systems are slightly different and will have different control methods.
The requirements and standards for equipment and wiring within the control panel will however apply for all projects.
The electrical equipment shall be such that its installation, operation and
maintenance shall comply with the above legislation and any subsequent relevant legislation.
CONTROL PANEL
Construction
As far as practicable, all controls, indicator lamps and instruments shall be grouped and mounted together in a floor or wall-mounted panel.
The control panel shall be constructed within a suitably sized powder coated steel enclosure, with a cream/grey finish (Bowthorpe Hellerman –
Himel type or equivalent). The enclosure shall incorporate removable gland plates at both top and bottom.
The control panel shall be constructed to give a protection rating of not less than IP55 and shall be so constructed as to prevent the ready ingress
of dust. The joints of plates and doors shall be suitably packed, using neoprene or equal (not rubber).
Mechanical ventilation shall be provided where it is likely that the operating temperature within the panel will be greater than those limits
set by the equipment manufacturer. That ventilation system shall maintain the panel temperature to within the manufacturers limits regardless of the panel environment.
Panels shall be supplied with hinged and lockable access doors at the front
of the panel. Two keys shall be provided which shall be common to all locks on all panels.
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All equipment within the enclosure shall be mounted on a removable back plate such that if required, the complete system can be removed from the
enclosure to aid installation.
Access doors or covers shall be so arranged that access cannot be made until an isolating device, interlocking with each door or cover, is opened and all equipment accessible through that door or cover is isolated. A
purpose made device or suitable isolator shall be provided to enable a competent engineer to override the interlock when the door has been
opened. Panels secured to the floor shall be provided with metal plinths of a
suitable size and strength i.e. ‘Unistrut’ or equivalent. This plinth must be earthed in accordance with BS7671 and BS 7430. Where mounting is on
raised builders work bases, metal plinths are not required, but in all cases fixing holes and detachable lifting eyes shall be provided.
Control panels shall, as far as is practicable, be manufactured, equipped, wired and tested before delivery to site.
Indicating lamps, instruments and controls shall be, as far, as is
practicable, from the same manufacturer and of the same style to provide uniformity of appearance and to facilitate maintenance. Externally visible equipment shall be flush mounted, with minimum projection and fixed
securely to the front panel.
Internal equipment shall be secured to the back plate using a suitable DIN type rail. Fixings shall incorporate shake-proof washers or other vibration resistant fastenings.
The control panel shall be designed and built by an approved control
specialist and shall comply in general with the details given by the Energy Management Unit and the project documentation supplied.
The control specialist shall supply working drawings and fully numbered interconnection diagrams to enable an electrical contractor to make all
connections between the control panel, plant and sensors.
This shall be deemed to include all valves, pumps, sensors, remote relays and all other forms of ancillary equipment associated with the controls package.
The electrical contractor shall be responsible for all connections external
to the control panel and for this reason, the panel shall be constructed such that all connections for both low voltage mains wiring and extra low voltage control, monitoring and data and monitoring wiring are made to a
single DIN rail terminal strip located at the top or alternatively the bottom of the enclosure.
The DIN rail terminal strip shall be arranged such that low voltage mains wiring and extra low voltage control, monitoring and data connections are
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segregated and suitably labelled. Mains voltage and low voltage cables must be segregated by a fixed barrier in accordance with IEE Regulations.
All terminals shall be numbered using appropriate slip on numbers, in
accordance with the panel wiring diagram. Note - the Users Guide to Wiring Allen-Martin Heating Controls
contains drawings for connections to all common equipment.
A label shall be fitted inside each control panel, adjacent to the main isolator indicating:
� Supply voltage � Control voltage
� Current rating � Date of manufacture
After installation the electrical contractor shall ensure that all swarf, dust and cable debris is removed from the panel.
Particular care shall be exercised when working around the energy control
system. The electrical contractor shall be responsible for and damage resulting
from this cleaning.
Control equipment The building management control equipment shall be from the Allen-Martin range of controllers unless specified otherwise by Cornwall Council.
The BMS controller shall be contained within the control panel. It shall be fed from a 5A rated un-switched spur taken from the live side of the
incoming isolator such that the supply to the controller is not isolated when the panel supply is switched off.
A durable yellow notice with black text to this affect shall be located adjacent to the isolator. This label shall be engraved traffolyte type and
affixed with mechanical fixings, not adhesive.
A single data socket shall be located within the panel for connection to the building intranet system.
A single socket outlet shall be fitted within the panel for the connection of a power supply for dialup modem communications when used.
A space shall be set aside for the subsequent mounting of a suitable power supply and modem unit. Both shall be fixed via proprietary
mechanical fixings.
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No interface whatsoever shall be made with the BMS module. All connections shall be via the incoming terminal strip.
All wiring within the control panel shall be identified at each end with a
number unique to that cable. Numbers shall only change due to a control device.
All wiring within the control panel shall be terminated using ferrule type crimp lugs constructed in accordance with the manufacturer’s instructions.
All panel wiring shall be single core, flexible plain annealed copper conductor, heat resistant PVC insulation. Panel wire to BS6231 type CK
and UL/CSA approved. 600/1000 volts grade.
Wiring within the control panel shall be contained within slotted trunking with close fitting lids. Trunking shall be Critchley betaduct or approved equivalent.
Internal wiring shall be colour coded to BS7671 for LV cables
ELV cables shall be coloured as follows:
24V a.c. White 24v (0V) Black 15V + ve Orange
15V –ve Grey Analogue input Purple
Analogue output Brown with marker Digital output Brown Digital input Pink
MCB’s shall be used in preference to BS88 fuses and these shall be type C
M9 to BS 60898 for all motor circuits. They shall be selected from the Merlin Gerin Multi 9 range.
All protective devices shall be so sized and co-ordinated that they provide shock and overload protection to BS7671.
Contactors shall be DIN rail mounted and from the Telemechanique range. Overload protection is required for all circuits. The full load current of all
circuits shall be recorded on the as fitted drawings and established to provide the correct setting of the overcurrent element.
Relays shall be DIN rail mounted and from the Omron/Shrack plug in range.
Panel indicator lights shall be from the Telemechanique high output LED
range. All indicator lamps shall be coloured for their mode according to BS EN 60073:1993, IEC 60073:1991.
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Running Green Tripped Red
Healthy White Fault Red
Warning Orange/Amber Abnormal Blue
Switches shall be from the Telemechanique range such that they match the selected indicators.
Volt Free Contacts (v.f.c.) shall be provided for all items of plant to enable alarm/status signal to be sent to the BMS.
The control panel shall be fitted with a key operated (tumbler type)
maintenance override switch. The switch shall be fitted on the front of the panel. Operating the switch shall run all plant and open all 240V operated valves and solenoids.
It shall not be possible to open to open any other valves by using the
plant maintenance override switch.
A red indicator lamp shall be fitted adjacent to the override switch and shall be illuminated when the switch is operated.
The switch shall be labelled “Plant maintenance override ON/OFF” The indicator shall be labelled “Override ON”.
Pressure switches
Two pressure switches shall be fitted on the cold feed to the system, these shall be the high and low limit switches. The set points shall be agreed
with a representative of Cornwall Council/Principal Mechanical Services Engineer at the commissioning stage.
Activation of either of these pressure switches shall cause the plant to be shut down immediately and display a “Pressure Fault” on the main control
panel. The control specialist shall also allow for the provision of “Closed when Healthy” signal to open under these fault conditions and initiate a fault alarm on the BMS. The fault condition will latch and will require local
or remote manual resetting.
Commissioning The contractor is to allow for the programming of all testing and
commissioning works to suit the programme of works.
This is to include inspecting, testing and commissioning of all works by any sub contractors and specialist contractors works arranged by the contractor.
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Commissioning shall mean the advancement of the systems from static completion to working order, to the specification, and relevant works to
achieve compliance with Part L of the building regulations and functionality to the complete satisfaction of Cornwall Council’s approved
representative/s. All shall be conducted without prejudice to the need to comply with all
Health and Safety requirements.
Commissioning works shall include, but not be limited to, the following: • Demonstrate the correct operation of all items of equipment
necessary to provide a working building energy control system • Demonstrate the correct operation of all alarm systems and provide
instruction to appointed site personnel involved in daily use and maintenance of the system
• Demonstrate the correct operation of all specialist plant and
equipment supplied and installed as part of the contract/works • Demonstrate the correct procedures for fault finding and reporting
in the event of mechanical or electrical faults within the installed works
The specialist contractor shall appoint an engineer to commission the complete system. The whole or part of the process shall be witnessed by
a representative of Cornwall Council/Principal Mechanical Services Engineer. The data link shall not be accessed until that representative is
present. Failure to comply could result in damage to either the new or existing
equipment.
The processor shall not be energised. As fitted control drawings shall be supplied immediately upon completion
of the project.
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HEATING/HWS CONTROLS
GENERAL TECHNICAL
SPECIFICATION
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General Technical Specification
Heating/HWS Controls
Preface
This technical specification is written as general guidance to the methods of control and the required standards for new and retrofit heating/hws
control systems. It shall be read in conjunction with the STANDARD CONTROL SPECIFICATION.
It is not intended as a definitive method statement, as all systems are slightly different and will have different control requirements. It should
therefore be read in conjunction with the relevant project documentation.
The requirements and standards for equipment and wiring within the control panels will however apply for all projects.
Heating System Operation (General)
The Allen Martin Series of Controllers are fully microprocessor controlled Building Management Systems which can be used to control heating and
ventilation plant. The controllers have a self learn facility which will determine the optimum warm up time of the building from the inside and
outside sensors fitted in various locations within the building. The controller will start the pump(s), fire the boiler(s), open the valve to
each zone (where applicable) and energise the supply to heat emitters (e.g. fan convectors - where applicable) to heat each zone as required.
When each heating zone is up to temperature, the controller may close or modulate the valve to that particular zone.
In the case of mixed flow (variable temperature) circuits with modulating
valves, the pumps shall continue to run to provide circulation. For constant temperature circuits fitted with 2 port isolating valves, the
pumps shall be stopped as soon as the valve closes by the use of an auxiliary switch within the valve actuator.
When all heating zones are up to temperature and switched off by the controller, the boiler shall be shut down.
Primary loop pumps (where applicable) or selected zone heating pumps
(dependant upon the type of installation) shall continue to run on for a predetermined time to dissipate excess heat within the boiler.
In general, the boiler and loop pumps (where applicable) shall be interlocked such that if the loop pump trips, the boiler will be shut down.
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If a pressurisation unit is fitted to the system, high and low pressure switches shall be fitted to the cold feed line. Operation of either switch
will indicate an abnormal system pressure condition and shall cause all plant to be shut down. This may be achieved by wiring the main control
circuit through the pressure switch system. Pressure fault indication shall be made available to the BMS in the form of
a volt free normally closed contact.
Compensation/optimisation of the system shall be achieved by the use of immersion type flow and return sensors within the system pipe work.
The type and number of such sensors will be dependant upon the requirements and degree of control required for each project.
Control of air handling plant shall be achieved in the same way except that the sensors shall be of a type suitable for installation within ducts.
The control panel shall be fitted with a plant over ride timer. This will
operate the plant so that the engineer can test pumps etc. This timer should be of a run back type so that the plant can not be left on.
Control Panel/Outstation
The control panel/outstation shall be designed and built by a control specialist and shall comply in general with the details given on the one
line schematic drawing provided with the project documentation and within this specification.
The control specialist shall issue working drawings and fully numbered interconnection diagrams to enable an electrical contractor to make all
interconnections between the control panel, plant and sensors.
This shall be deemed to include all valves, pumps, sensors, remote relays and all other items of ancillary equipment associated with the controls package.
All terminals shall be numbered in accordance with the panel wiring
diagram. No plant or sensors shall be directly connected to the mother board or
modules thus bypassing the main terminal strip.
All wiring within the control panel/outstation shall be easily identifiable by the use of wire and terminal numbers. All cables shall be marked at both
ends within the panel. All cables to be tri rated to BS 6231. Outgoing wiring from the terminal strip shall be fitted with terminal
numbers at the panel and remote ends such that they can be easily identified during testing and commissioning.
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Wiring within the control panel to be contained within suitable trunking with access slots (e.g. Critchley Betaduct).
Volt free contacts shall be provided for all items of plant to enable
alarm/status signals to be sent to the BMS. E.g. each zone pump will have volt free contacts for both running and
tripped states.
Alarms and trips shall be closed contacts that open on trip, running contacts will open when running.
Panel Installation
The electrical contractor shall be responsible for the fixing and connection of the control panel and shall ensure that the control system is protected
during installation.
The electrical contractor shall remove all gland plates and panel entries for drilling and slotting for cable entries. He shall not drill gland plates with the control equipment in place unless suitable precautions have been
taken to prevent the ingress of swarf and filings into the contactors/relays etc.
The contractor shall ensure that the trunking/conduit connection to the panel is of sufficient width such that only the removable gland plate needs
to be perforated.
Any stray swarf or filings found within the panel after installation shall be cleaned out with a vacuum cleaner.
Any damage to equipment within the panel which can be attributed to the ingress or swarf and filings shall be rectified at
the expense of the installer.
Pump Control
Zone heating and HWS pumps within the boiler house area shall be controlled by the BMS via the control panel.
Remote pumps shall be controlled from the BMS by the use of extra low voltage relays in the remote location, which will switch the
pump/associated equipment. Supplies to remote equipment shall be derived from a local distribution board and suitably labelled.
If 2 port valves are used (where applicable), pumps shall be prevented from running until the two port valves are full open by the use of valve
end switches. Under no circumstances should a pump be made to operate against a closed valve.
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Under normal operating conditions, the BMS will control the valve and the pump will only start when the end of travel switch within the valve
actuator operates as the valve approaches the full open position.
The controls specialist shall be made aware if there are valve end switches and their required function.
The end switches are usually supplied as a separate item and will require fitting into the valve actuator at installation and adjusting to the required
end of travel tolerance. End switches shall not be used for direct control of signals or supply. End
switches shall operate slave relays in the control panel only.
Switches shall be provided on the control panel for each pump. These switches shall be Off/Auto only. No hand override shall be provided.
Twin head pumps shall be controlled on an either/or basis and no automatic changeover shall be allowed.
All pumps shall be fitted with appropriately sized overload relays wired
into the contactor control circuit or a suitable alternative.
Remote Relays
Remote relays used to drive equipment not located within the boiler house
shall in general be an extra low voltage type capable of being driven directly by the digital output from the BMS or through a relay located
within the control panel. If the output from the BMS is of insufficient capacity to drive the number
of relays required, a suitable transformer shall be fitted within the control panel to provide an extra low voltage supply for these relays.
The remote relays must be wired such that they are energised to switch off the plant they control. For this reason, if they are controlled by a LV
transformer and relay within the panel, the control specialist shall ensure that the system is capable of providing the required output.
This is required so that in the event of a control system failure, all plant will run.
For connection of remote relay, see enclosed drawing.
Boiler house wiring
Wiring within boiler houses and/or plant rooms shall be in PVC single core
tri rated cable contained within galvanised steel conduit and trunking. Final connection to sensors shall be made in flexible conduit with the cable drawn through.
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Two compartment trunking shall be installed within the boiler house where required to carry extra low voltage and data and low voltage mains wiring.
It is not acceptable to run data cables and mains cables in the same
conduit or trunking unless a metallic barrier is fitted (ref section 528 of British Standard BS 7671). In all instances of cable routing the manufacturers recommendations shall be adhered to.
Data cable will be terminated in a suitable galvanised box. The box will
have a numbered din rail mounted terminal strip. The cable will be numbered at both ends and the box lid will have a label stating DATA.
Sensor and Control Wiring
The zone sensors shall be wired in the type of cable as specified by the appropriate control drawing but generally to BS5308.
This cable shall physically isolated in the data isolation box for remote
sensors and in by the compartment trunking in the boiler room. Immersion sensors and outside sensors shall be wired in data cable to CT
units (where applicable) and then to BMS via the terminal strip in the control panel.
Connection from the CT unit (where applicable) to immersion and duct sensors shall be in “Kopex” or equal and approved with the data cable
drawn through.
Connections to pressure switches etc shall be made as detailed for sensors.
Where room sensors are fitted to back boxes or other outlets, the end of the conduit or back plate of the sensor shall be sealed with a suitable non
setting compound to prevent the ingress of air and draughts from areas external to the controlled space.
Sensors and thermostats shall be mounted at 1650mm above finished floor level. Spur for the thermostat shall be mounted at 150mm below
finished ceiling level.
In rooms containing both thermostats and room sensors, the units shall be mounted adjacent to each other in the same location within the space.
Isolation
All boilers shall be fed via a multipole isolator mounted adjacent to the
equipment for mechanical maintenance purposes. This shall be capable of interrupting all live conductors of the supply to each boiler/boiler module.
(Note as BS7671 the neutral is viewed as a live conductor).
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Pumps shall be fed from the control panel via 16A European standard IEC plug and sockets (e.g. Mk Commando range or similar) and using heat
resisting flexible cable to the pump heads.
The socket shall be installed socket facing downwards. Pressurisation units shall be fed on a permanently live supply from the
control panel via a 16A IEC plug and socket.
Pressurisation unit (where applicable)
Two pressure switches shall be fitted on the cold feed to the system, these shall be high and low limits. The high limit shall be a break on rise unit
and the low limit shall be a break on fall. These limit switches shall control slave relays in the control panel.
The set points shall be agreed with the mechanical engineer at commissioning stage.
Operation of either switch shall cause all plant to be shut down immediately and display a pressure fault indication on the main control
panel. The control specialist shall also allow for the provision of volt free normally closed contacts that open under fault conditions to enable the
fault alarm to be detected by the BMS. The pressurisation unit shall be wired on an exclusive circuit from the
control panel via a 16A European standard fused spur.
Control valves/AHU Dampers
Control valves (where applicable) shall be 2 port for isolation and three port for mixing or diverting.
The valves/actuators selected shall be dependant upon the particular project and may be either mains or low voltage operation.
All extra low voltage (e.g. 0-10V) operated valves shall be wired with a
suitable multicore cable with a cross sectional area of not less than 1.5mm2 to allow for the possibility of voltage drop.
Refer to the appropriate control drawing.
Telephony/Belden type cable shall not be used for this purpose. The mechanical contractor shall in general supply the valves and actuators
and the type/operating voltage shall be indicated on the one line schematic provided as part of the project documentation.
Mains operated valves shall be terminated with in the valve head. Labels shall be installed to warn about voltage.
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The control specialist shall ensure that the panel is fitted with a suitable transformer, which is capable of supplying the total connected extra low
voltage load.
HWS Controls
In general, the HWS system shall be controlled by the BMS by the use of a three port diverting valve on the primary circuit controlled via an immersion type sensor within the cylinder.
High limit control shall be achieved by a 230v 50Hz spring return 2 port
isolating valve that cuts off all primary flow to the cylinder. This shall be controlled by a high limit thermostat located within the cylinder.
Immersion heaters for standby use shall be fitted within the cylinder and controlled by the BMS on a timetable basis if there are sufficient outputs
on the control system. If the heaters are to be manually controlled, they shall be switched from
the plant control panel. A visual indicator shall be provided on the panel to show that the standby immersions are in use.
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Responsibilities (heating/hws plant)
The electrical contractor shall be responsible for:
E1. Mounting and positioning of all equipment
E2. Running of all cables
E3. All wiring and final connections to sensors plant and control
systems to clear and concise wiring/installation diagrams provided by the control specialist
E4. All wiring and final connections to heating equipment as detailed
on the project drawings
E5. Supply and installation of all controls, sensors and ancillary
equipment E6. Full inspection and test of the whole electrical installation
including mechanical control. Certificate to be produced.
E7. The purchase of all control equipment and associated items from one of the nominated controls specialists for the particular project
Controls Specialist
The control specialist shall be responsible for:
a) Designing and building of the control panel/outstation
b) Final testing and commissioning of plant and control system
c) Liaison with Cornwall Council Energy Management Unit and/or Clerk of Works
d) Provision of all wiring and interconnection diagrams as detailed
within this specification. This shall include a fully annotated
termination diagram giving terminal number/letters for all items of plant and the respective connections within the control panel
terminal strip. It shall also give details of cable type, cross sectional area and colour coding where applicable.
These diagrams will provide the electrical contractor with sufficiently detailed information to enable him to make all necessary
interconnections between plant items and controls. e) As fitted controls drawings on completion of the project.
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Data Link (where applicable)
The electrical contractor shall allow for the supply and installation of a data link from any existing compatible BMS controls to the new control
panel/BMS. This link shall be a multi-core data cable to BS5308 and shall be run to the nearest energy management outstation within an existing
building/area. The data link between new and existing equipment shall be left
disconnected until the new control system is ready to be commissioned. Failure to do this can result in damage to either the existing or new
control equipment. If the installation is a completely new project or there are no existing
compatible controls, the above shall not apply.
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LPHW Heating Systems Control Philosophy
If Then
Heating zone calls for heat Valve opens (2 or 3 port)
Loop pump starts (where fitted) Zone heating pump starts
Fan convector circuit energised (Where fitted) Boiler(s) fire Run indication for each item to BMS and on
panel
Zone up to temperature (variable temp circuit)
3 port valve modulates under BMS control Pump continues to run to circulate pipework
Zone up to temperature
(constant temp circuit)
2 port isolating valve (where fitted) closes
Circulating pump stops Fan convector zone controls (where fitted) switched off
All zones up to temperature Boiler stops Loop pump (where fitted) runs on to dissipate heat in boiler
This may be a zone pump if no loop pumps fitted
Pressurisation unit failure
(where applicable) or system pressure fault
All plant stops
Alarm signal sent to BMS Pressure fault indication on control panel
Boiler lockout occurs Alarm signal to BMS
Lockout indication on control panel
Zone pump trips Alarm signal to BMS Trip indication on control panel
Loop pump trips (where fitted)
Alarm signal to BMS Trip indication on control panel
Boiler shuts down
Plant override switch operated
All valves open (except 0-10V analogue control)
All pumps run Boilers fire (controlled by integral stats)
Fan convector circuits energised
Control system fails All plant runs Boilers control on integral stats Fan convectors control on local room stats
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Fire alarm operates (interlocked via f/a auxiliary
contact in control circuit)
All plant shuts down Gas solenoid valve closes (if fitted)
Gas drop valve solenoid releases (if fitted)
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Ventilation and Air Handling Control Philosophy
If Then
Space requires ventilation (over
temp/poor air quality)
Control system checks outside and
inside air temperature
Outside air temperature low Heater battery (if fitted) brought on line (operates in a similar way to a
mixed flow heating zone except that 3 port valve is used for diverting rather
than mixing)
Outside air temp below 5c (measured by stat on heater battery
Fans held off to prevent chilling/freezing of heater battery
If above conditions satisfied Supply and extract fans start
Dampers open to allow fresh air into space (incoming air tempered by heater battery if required)
Space at required temperature Supply/extract air dampers modulate
to provide partial fresh/recirculated air via heat exchanger
Summer cooling required Supply and extract fans start, dampers
open allowing fresh air into space thus providing free cooling. Temperature within space monitored by duct sensor
in return duct
Low space temperature Heater battery brought on line, supply (external) air damper closes, system
recirculates until space temperature comes up to required level
Dampers then modulate to maintain temperature/air quality Space temperature monitored by return
air duct sensor
Space up to temperature Heater battery 3 port valve modulates to divert flow away from battery
Valve controlled by system based on return air temperature as monitored by return air duct sensor
Dampers modulate to maintain temperature and air quality based on
return air temperature as measured by return duct sensor
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Air handling fans trip Trip indication shows on control panel Alarm signal to BMS
Fire alarm operates All fire dampers close (where fitted) Fans stop
System requires manual reset after fire alarm cleared
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Prepared by:
Terry Thomas
Principal Electrical Engineer
Property Services
26 August 2010
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If you would like this information in another format please contact:
Cornwall Council County Hall
Treyew Road Truro TR1 3AY
Telephone: 0300 1234 100
Email: enquiries@cornwall.gov.uk
www.cornwall.gov.uk