TMG G1520 SIGNALLING EQUIPMENT TEMPERATURE CONTROL GUIDELINES Version 2.0 Issued September 2012 Owner: Chief Engineer, Signals & Control Systems Approved by: Warwick Allison Chief Engineer Signals & Control Systems Authorised by: Paul Szacsvay Principal Engineer Signal Research & Development Disclaimer This document was prepared for use on the RailCorp Network only. RailCorp makes no warranties, express or implied, that compliance with the contents of this document shall be sufficient to ensure safe systems or work or operation. It is the document user’s sole responsibility to ensure that the copy of the document it is viewing is the current version of the document as in use by RailCorp. RailCorp accepts no liability whatsoever in relation to the use of this document by any party, and RailCorp excludes any liability which arises in any manner by the use of this document. Copyright The information in this document is protected by Copyright and no part of this document may be reproduced, altered, stored or transmitted by any person without the prior consent of RailCorp. UNCONTROLLED WHEN PRINTED Page 1 of 2 Engineering Guideline Engineering Guideline Signals RailCorp Engineering Guideline — Signals Signalling Equipment Temperature Control Guidelines TMG G1520 Document control Version 1.0 2.0 Date 2/04/2007 19/09/2012 Summary of change First issue Document number TMG G1520 applied. Cover pages complying with TMA 400 Engineering Publications Manual attached to front of document to facilitate publication. Forming part of this document is the Signalling Equipment Temperature Control Guideline dated 2 April 2007. The original document consists of 17 pages. © RailCorp Issued September 2012 UNCONTROLLED WHEN PRINTED Page 2 of 2 Version 2.0 Signalling Equipment Temperature Control Guideline TABLE OF CONTENTS 1 INTRODUCTION 3 2 TYPICAL TEMPERATURE RELATED PROBLEMS 3 3 EQUIPMENT TEMPERATURE REQUIREMENTS 4 4 HEAT GENERATED BY EQUIPMENT 5 5 LOCATION CASES 6 6 BUNGALOWS 7 7 BUILDINGS 8 8 MOUNTING OF EQUIPMENT 8 8.1 GENERAL EQUIPMENT 8 8.2 Q RELAY RACK MOUNTED EQUIPMENT 9 8.2.1 Track circuit equipment 9 8.2.2 Resistors 9 8.2.3 Relays 10 8.3 NS1 RACK MOUNTED TRACK CIRCUIT EQUIPMENT 10 8.4 G RAIL (OR TOP HAT RAIL) MOUNTED EQUIPMENT 12 8.4.1 Resistors 12 8.4.2 Ancillary equipment 12 8.4.3 Power supplies 12 8.5 19 INCH RACK MOUNTED 12 8.5.1 Power Supplies 12 8.5.2 Heat sensitive equipment 12 8.6 WALL MOUNTED 13 8.7 FLOOR MOUNTED 13 8.8 EQUIPMENT CONTAINING FANS 13 9 EXTERNAL EQUIPMENT 13 10 SHADE STRUCTURES 13 11 ROTARY ROOF VENTILATORS 14 12 AIR CONDITIONING 14 13 SPARE EQUIPMENT STORAGE 15 14 REMEDIAL ACTIONS 15 Appendix - Ventilation requirement calculations 2/04/2007 Page 2 of 17 16 Signalling Equipment 1 Temperature Control Guideline Introduction This document provides guidelines on: • Lay out of equipment on racks for heat related issues. • Limits for heat loads in various types of locations and buildings. The aim is to include temperature control as a significant factor when considering the positioning of equipment on racks, within locations, bungalows or buildings. Some areas experience higher temperatures due to their natural environment and therefore need more effort to control equipment temperatures. The results from temperature recording and analysis have shown that improved ventilation provides the most significant measurable improvement to internal ambient temperatures compared to double skinning or tropical roofs. However improved ventilation also increases dust in locations. Improving the thermal insulation of Signalling buildings and location cases can reduce the amount of ventilation required. Signalling buildings and location cases should move towards meeting thermal requirements similar to the minimum star rating of the Nationwide House Energy Rating Scheme (NatHERS). Detail of NatHERS is available on the Internet at www.nathers.gov.au. 2 Typical temperature related problems Prolonged exposure to operating temperatures at or near the equipment's rating is known to reduce the life of electronic equipment. Short-term ambient temperatures at or near rated maximums can cause: • Increased sensitivity to electrical noise, which can lead to failure, if electrical noise is present. CBI equipment like SSI and Microlok has exhibited this type of failure. • Drift in operating parameters, which may cause permanent failure, intermittent failure, or fail the equipment whilst it remains above a particular temperature. Older telemetry systems have exhibited this type of failure. CSEE UM71 Txs lower their output power available, CSEE UM71 Rxs pick up threshold increases. • Shutdown the equipment due to built-in over temperature controls. Aldridge LED signal lights, and power supplies have exhibited this type of failure • Component failure. This type of failure has been reported for most types of equipment. 2/04/2007 Page 3 of 17 Signalling Equipment Temperature Control Guideline Long term operating temperatures (typically >45ºC): • Reduced equipment life, which leads to an increased failure rate of the equipment. Older Store 93 power supplies have had this type of failure. Equipment installed in underground railway tunnel locations has also had this problem due to continuous high ambient temperatures. Large temperature cycles (day/night changes of >25ºC): • Reduced equipment life, which leads to an increased failure rate of the equipment. Older telemetry systems have exhibited this type of failure. • Different expansion and contraction rates for the materials can result in stress causing internal connection problems that cause permanent failure, or intermittent failure, or temperature dependant failures of the equipment. Older telemetry systems have exhibited this type of failure. • Instability in temperature compensation circuits. TI21 track circuits may exhibit this type of failure. Low temperatures causing water to condense or drip onto equipment: • At low temperatures condensation can occur on internal surfaces due to the difference between wall or roof temperature (cold) and internal air temperature (warm). Water can then drip on exposed equipment and cause failures. This problem can also occur in external equipment. 3 Equipment temperature requirements The initial part of this section provides minimum and maximum temperatures ratings of commonly used equipment. These ratings do not include any de-rating to improve longevity or reliability of the equipment. Typical track circuit equipment ratings are: • Jeumont Schneider track circuit equipment is rated for 0 to 70º C. • TI 21 track circuit equipment is rated for 0 to 70º C. • FS2500 track circuit equipment is rated for 0 to 60º C. • CSEE UM71 track circuit equipment is rated for –30 to +70º C. RailCorp Signalling Equipment specification SPG 1020 Power supply units for Signalling Equipment - General requirements requires 0 to 70ºC temperature rating. Commercial power supplies used are rated to 55ºC but are operated at a reduced load to allow operation at 70ºC. Q relays are type tested at 55ºC for most aspects and 60ºC for coil operation. Westinghouse Mark IIIA SSI TFMs are rated for -20 to +60º C. 2/04/2007 Page 4 of 17 Signalling Equipment Temperature Control Guideline Microlok II equipment is specified as –40 to +70º C but some ancillary equipment associated with Microlok II is only rated to 55ºC. The 55ºC rated ancillary equipment typically does not generate significant amounts of heat. Most wiring used in signalling installations is V75 rated which means that the wire including the heat rise due to the electrical current carried must be kept to less than 75ºC. The SAK terminals are suitable for their full rating up to 85ºC. The Z series terminals used with Microlok II are suitable for their full rating up to 75ºC. A set of objectives to control these effects is: • Normally operate the equipment no higher than 10ºC less than its rated temperature for at least 90% of the time in the hottest month. • Allow equipment temperature to reach its maximum rated temperature only on days that reach 35 to 40º C. • Keep the day night temperature change for the equipment to less than 25ºC. • Provide buildings or location cases that are designed to extract the heat generated by the equipment installed. This guideline meets these objectives (as well as the Signals Standards requirements) by trying to balance the heat loads of locations with the ventilation provided and the protection from the heat produced by direct sunlight. 4 Heat generated by Equipment The heat generated within signalling locations and buildings comes from the consumption of electricity. Typically less than half the VA load of a location will be dissipated as heat within the location as some power is fed into signal lights, train stops, the rail ballast by track circuits, etc. The other reduction is due to the power factor being less that 1. Typically the power factor is about 0.9. An assessment of equipment generated heat gives: Equipment Heat dissipation estimate (Watts) SSI Transformer (500VA) 20 Power Transformer 40 per kVA SSI TFM 25 Microlok II card file (1/3 full) 20 Microlok II card file (2/3 full) 40 Audio Track Circuit PSU regulated (Store 93). 25 Audio Track Circuit PSU unregulated. 12 Audio Track Circuit Tx 12 2/04/2007 Page 5 of 17 Signalling Equipment Temperature Control Guideline CSEE UM71 Rx 6 TI21, FS2500 Rx 10 Jeumont Schneider PSU 15 Jeumont Schneider Tx 15 Jeumont Schneider Rx 3 General, relays etc 1 per relay. See Note. Static Switch 5kVA 100 Static Switch >5kVA 250 UPS 75 per kVA Note: Averaged value taking into account the percentage of energised relays and relay heat dissipation. 5 Location Cases Equipment installed in location cases is subject to wider temperature swings and more extreme temperatures. Standard location cases that do not have temperature control measures like doubleskinning, improved ventilation, or shade structures should have equipment rated for at least 60oC. However 55oC rated equipment (that does not produce significant heat) can be installed in the bottom half of the location. Location cases that have temperature control measures like double-skinning, or shade structures may have some ancillary equipment rated for 45oC but where practical it should be rated for 55oC or more. Location case sizes are defined in terms of single, double, or triple width. A door is provided for each unit of width. Location cases that have not had their ventilation upgraded are estimated to handle a maximum of 80 watts equipment generated heat load per width. The design approach is to use convection airflow from an air inlet vent at the bottom (below equipment mounting level) to an air outlet vent at the top (above the equipment mounting level) to remove heat. Location cases should have one of the following treatments: • New locations should be double skin with ventilation for 200 watts equipment generated heat load per width. This is one inlet air vent below each door sized approximately 150mm high by 800mm wide. The width should match the door width. Outlet air vents should be of equivalent or larger size to the inlet air vents and located above the highest equipment mounting point. Inlet vents can also be provided low down on the sides of the locations and the vents under the doors reduced appropriately. 2/04/2007 Page 6 of 17 Signalling Equipment Temperature Control Guideline • Existing locations in original condition: Double-skin the location using an approved double skin location case design that has the required level of ventilation. • Existing locations with Tropical roof: Provide vented roof, with door and side vents to location case. Or Double-skin the location using an approved double skin location case design. Or Provide 300mm passive rotary roof ventilator and bottom inlet vents. This requires 100 x 800mm of inlet vent below each door. Location cases that have had their ventilation upgraded as above are estimated to handle a maximum of 200 watts equipment generated heat load per width. Locations must not have horizontal internal ceilings, all location ceilings should have a slope of at least 2.5º (30mm drop in 620mm) to ensure condensation runs to the side and does not drip onto equipment. This minimum slope is based on existing location cases. A larger slope of 4º (45mm in 620mm) is preferred. Internal ceilings of locations must not have any protrusions or points where condensation can collect and drip from that are directly above equipment mounting positions. Rafters or support members running across the line of slope especially promote the forming of drips. 6 Bungalows Standard concrete bungalows that do not have temperature control measures like improved ventilation, or shade structures must have equipment rated for at least 55oC. Concrete bungalows that have temperature control measures like additional shade roof, and shade panels, or active cooling may have some ancillary equipment rated for 45oC but where practical it should be rated for 50oC or more. Bungalows that do not have proper ventilation should have a maximum of 330 watts equipment generated heat load. The typical maximum is 1000 watts equipment generated heat load for a properly ventilated bungalow. However in exceptional cases the equipment generated heat load can be up to 3000 watts provided that appropriate additional temperature control measures are implemented. Bungalows should have: • A 400mm industrial rotary roof ventilator with 0.5 m2 of unrestricted inlet air vents for the room in the bungalow. This normally means enlarging the door 2/04/2007 Page 7 of 17 Signalling Equipment Temperature Control Guideline vent to 600mm wide by 700mm high, which combined with the wall vents should meet the 0.5 m2 of unrestricted inlet air vents requirement. Suppliers recommend that the inlet air vent area should be 4 times the throat area of the rotary roof ventilator. • Vandal resistant cages for the roof ventilators. The cages must not significantly restrict the air flow. or SkycoolTM heat reflective coating to reduce solar heat gain. External walls are not painted, as it would make the bungalows too prominent and may be cause for complaint by nearby residents. • Roof painted with Solacoat 7 TM Buildings Standard double brick signalling locations with 2.4m ceilings must have equipment rated for at least 55oC. Standard double brick signalling locations with ceilings higher than 2.4m may have some ancillary equipment rated for 45oC but where practical it should be rated for 50oC or more. Brick or large buildings with active cooling, additional ventilation or additional thermal insulation have significantly better temperature control of the equipment than the standard brick signalling locations. Ancillary equipment rated for 35oC may be used in this case but where practical the equipment should be rated for 45oC or more. The equipment generated heat load should be calculated based on the heat removal provided. Typically the permissible equipment heat load will be more than that of a bungalow and thus a properly designed brick building is preferred to a bungalow on this criteria. 8 Mounting of equipment 8.1 General equipment Signal Construction Specification SPG 0707 Specification Installation of equipment racks and termination of cables and wiring Clause 2.2.2 requires: • Equipment to be mounted between 300 and 1800mm above ground or floor level. • Heat producing equipment mounted so it does not damage equipment above or beside it. The following sections detail the preferred method of complying. 2/04/2007 Page 8 of 17 Signalling Equipment 8.2 8.2.1 Temperature Control Guideline Q relay rack mounted equipment Track circuit equipment TI21 and FS2500 track circuit transmitters, receivers, and power supplies mount on Q relay racking. TI21 transmitter and receivers are 2 1/2 Q spaces wide. A 1/2 Q relay space must be left between adjacent modules. This spacing is sufficient for normal installations. FS2500 transmitters and receivers are 2 Q spaces wide. A vacant Q space must be left between transmitters and other module types. The vacant Q space is preferred to be on the right-hand side of the transmitter. The standard minimum spacing of 50mm vertically between rows of Q relay racks is adequate. TI 21 track circuit equipment mounted with insufficient space between PSU and 1st module. 8.2.2 Resistors Positioning and mounting of resistors must address the heat that will be generated. Resistors that may dissipate 3W or more and are operated at more than 1/4 of their power rating must have 75mm of open space directly above them. Mounting terminals and backing plates must be rated for 70ºC. The Weidmuller MK4 mulitpole terminal blocks are approved. 2/04/2007 Page 9 of 17 Signalling Equipment 8.2.3 Temperature Control Guideline Relays Relays should not be fitted in the position directly above a resistor that requires open space directly above it. If relays are mounted in the row directly above track circuit equipment then a minimum of one relay position in 3 must be left vacant, while one vacant space in two is preferable. 8.3 NS1 rack mounted track circuit equipment CSEE UM71 track circuit transmitters, receivers, and power supplies are installed on the NS1 racking. The minimum vertical spacing between modules is 8mm. The minimum horizontal spacing between columns is 50mm. The minimum vertical space between modules is not sufficient when the modules produce more than 9 watts of heat. The following vertical spacing rules apply for UM71 Track circuit equipment: • Rx mounting: Rxs can be mounted with no space between Rxs. However Rxs must have two vacant PFC block spaces below when mounted above CSEE UM71 Tx, PSU or Jeumont Tx, PSU modules. • Tx mounting: Txs must always have one vacant PFC block space below and one vacant PFC block space above regardless of module mounted above or below. • PSU mounting: PSUs must always have one vacant PFC block space below and one vacant PFC block space above regardless of module mounted above or below. • Rxs should be mounted below Txs and PSUs. CSEE equipment on NS1 racking with insufficient space between Txs. 2/04/2007 Page 10 of 17 Signalling Equipment Temperature Control Guideline Jeumont Schneider Impulse track circuit equipment is installed on the NS1 racking. The minimum vertical spacing between modules is 8mm. The minimum horizontal spacing between columns is 50mm. The minimum vertical space between modules is not sufficient when the modules produce more than 9 watts of heat. The following vertical spacing rules apply to Jeumont Track circuit equipment: • Tx mounting: Txs must always have one vacant PFC block space above it. • PSU mounting: PSUs must always have one vacant PFC block space above it. • Rx mounting: Rxs can be mounted with no space between Rxs and between Rxs and relays or immediately below Txs or PSUs. However Rxs must have two vacant PFC block spaces below when mounted above Jeumont Tx, PSU modules or CSEE UM71 Tx or PSU modules. • Relay mounting: Relays can be mounted with no space between Relays and between relays and Rxs. However Relays must have one vacant PFC block spaces below when mounted above Jeumont Tx, PSU modules or CSEE UM71 Tx or PSU modules. • Relays and Rxs should be mounted below Txs and PSUs. • VDRs are considered to be equivalent to a vacant space. 189 watts of correctly spaced Jeumont track circuit equipment. Each door width can only handle 200 watts of heat load, so the equipment could be spaced out further. 2/04/2007 Page 11 of 17 Signalling Equipment 8.4 8.4.1 Temperature Control Guideline G rail (or Top hat rail) mounted equipment Resistors Positioning and mounting of resistors must address the heat that will be generated. Resistors that may dissipate 3W or more and are operated at more than 1/4 of their power rating must have 75mm of open space directly above them. Mounting terminals and mounting plates must be rated for 70ºC. The Weidmuller MK4 mulitpole terminal blocks are approved. 8.4.2 Ancillary equipment Ancillary equipment with temperature ratings of 55ºC or less should be mounted in the lower half of the location, as the temperature rise is less in the lower half of the location. 8.4.3 Power supplies Power supplies must be installed in compliance with the orientation and spacing recommended by the manufacturer. In general industry, mounting rails are horizontal rather than vertical, which may cause problems with ventilation of the equipment when mounting equipment on the vertical mounting rail. 8.5 19 inch rack mounted 1U is a vertical rack spacing measurement, which is approximately 45mm (or exactly 1 3/4 inches or 44.45mm). 8.5.1 Power Supplies Power supply sub-racks must have a minimum of 2U free space left above them and a minimum of 1U free space left below them. Generally power supplies are mounted higher in the rack. Power supplies are considered to be heat-producing equipment. 8.5.2 Heat sensitive equipment Heat sensitive equipment mounted in 19-inch racking must have a minimum of 1U free space above each sub-rack and 1U free space below each sub-rack. No heat producing equipment may be mounted within the 3U space immediately below the heat sensitive equipment. Generally heat sensitive equipment is mounted lower in the rack. 2/04/2007 Page 12 of 17 Signalling Equipment 8.6 Temperature Control Guideline Wall mounted Wall mounted heat producing equipment must have a minimum of 75mm free space below and on either side, and 150mm free space above it. Equipment mounted on walls should be mounted so that it is not hard up against the wall and preferably not mounted on a north or west wall. The recommended minimum stand-off distance is 12.5mm. Mounting is to comply with the orientation recommended by the manufacturer. 8.7 Floor mounted Floor mounted heat producing equipment must have a minimum of 75mm free space on either side, and 150mm free space above it. Mounting is to comply with the orientation recommended by the manufacturer. 8.8 Equipment containing fans Space must be left around the air inlet/outlet so that the air flow within 50mm of the air inlet/outlet is not impeded. A 100mm space of unimpeded airflow is preferred. Consideration should be given to the direction of the air flow to reduce dust entry. Typically the fan should draw air from below the equipment rather than from above or the side. Space must be left to allow the replacement of fans and/or filters. 9 External equipment Ensure that designs do not place equipment externally that has not been specifically approved for external mounting. 10 Shade structures Shade roofs need to be sloped to reduce the collection of heated air underneath the structure. The slope should be between 10 to 18 degrees to allow the heated air to escape. The low side should be on the North or West side depending on the available natural shade. The low side should be toward the North if no other shade is available. These guidelines are based on studies published by the CSIRO on shade structures. The roof slope can be reduced if the roof material is not solid and permits heated air to rise through the roof. Lysaght Louvamesh has been approved for use as part of shade screens. Vertically mounted mesh is installed with its longway opening horizontal and strands sloping outward and down. This is the manufacturer's recommendation for maximum shading effect. Provision of shade structures is secondary to the provision of proper ventilation. 2/04/2007 Page 13 of 17 Signalling Equipment Temperature Control Guideline Location cases still need to have appropriate ventilation (like the vented roof, and improved door and side vents) to allow internally generated heat to be removed. 11 Rotary roof ventilators Roof ventilators are Type 4 Rotating wind driven roof ventilators as per AS 4740 Natural Ventilators - Classification and Performance. These are called by various names including "whirlybirds" etc. Rain resistance should at least meet Class B, with Class A preferred. Effective aerodynamic area should at least meet Class 2, which is at least 50% effective area. Flow coefficient should at least meet Class 2, which is at least 50%. Wind loading should be at least Level 2. Industrial grade rotatory roof ventilators are to be used be they are more durable, and provide a higher airflow rate for a given wind speed than domestic models. The Hurricane Turbine series ventilators from CSR Edmonds have been approved. One 300mm Hurricane Turbine ventilator can be used on location cases. One or more 400mm Hurricane Turbine ventilators are used on bungalows and brick buildings. Ecopower Hybrid Turbine ventilators are induction motor assisted roof ventilators that use the motor assist while the internal temperature is above a temperature set by a thermostat. At lower temperatures they perform as a standard rotary roof ventilator. The Ecopower Hybrid 300mm Hurricane Turbine ventilator has been used in some installations but are not needed for usual situations. The current standard size for the Ecopower Hybrid Hurricane Turbine ventilators is now 400mm diameter. 12 Air conditioning Air conditioning should be provided only in extreme cases where the other means are not effective or not possible. Signal Construction Specification SC 12 20 00 00 SP (SPG 0708) Small buildings and Location cases sets the requirements for any air conditioner provided. The air conditioner should have at least a 4 star energy rating for cooling. The building should have an insulation rating of at least R2.5 for an air conditioner to be economically installed over its life cycle. Typical bungalows have an R value of about 0.25. This means that air conditioners installed in bungalows will have to have a much higher capacity to control the temperature on very hot days (as well as be more in-efficient because of the inadequate building insulation). Air conditioners should be rated for significantly more than the normal equipment heat load. Twice the equipment heat load is considered appropriate. 2/04/2007 Page 14 of 17 Signalling Equipment 13 Temperature Control Guideline Spare equipment storage Spare equipment is to be stored in an environment that does not shorten its life. The storage environment should limit the maximum storage temperature to less than 70ºC. The minimum storage temperature should be more than -5ºC. Nylon jacketed PVC internal wire (7/0.40) can be triggered to leak plasticiser due to storage at temperatures above 70ºC. 14 Remedial actions Priorities for work to improve ventilation for existing locations, or buildings should be based on: • Bungalows that currently have poor ventilation (that is undersized/no rotary roof ventilator, or rotary roof ventilator with a door vent of less than 600mm by 450mm.) • Quantity of Audio, and Jeumont track equipment with close spacing. (High heat load) • Quantity of CBI equipment (High heat load plus sensitive equipment). • Locations in full direct sun from 9am to 4pm. • Areas known to experience hotter temperatures like Western Sydney. 2/04/2007 Page 15 of 17 Signalling Equipment Temperature Control Guideline Appendix - Ventilation requirement calculations The appendix contains reference information that details how the ventilation requirements were derived. The heat transfer equation for air is: Q= 0.05 W /Tc Where: Q is the airflow required in m3/minute. W is Heat dissipated in Watts. Tc is outlet air temperature rise above air inlet temperature in degrees Celsius. Typical air speed for convection airflow is given as about 0.2m/s, which implies that the air takes 10 seconds to flow from bottom to top of a location case. Fixed grilles or louvre panels Location case vents are Type 1 Fixed grilles, louvre panels as per AS 4740 Natural Ventilators - Classification and Performance. Rain resistance should at least meet Class B. Effective aerodynamic area should at least meet Class 2, which is at least 50% effective area. Wind loading should be at least Level 2. Location cases Given an aim to limit heat rise in the location to 7ºC due to internal heating and allowing up to 3ºC heat rise due to solar heat gain. This is based on using a double skin location case. Expected maximum internal heat load for a location case is 200w per door width. For a single width location case the calculation is: Q= 0.05 x (200) / 7 = 1.4 m3/m Inlet area = Q / Speed (in m/minute) Inlet area = 1.4 / (0.2 x 60) Inlet area = 0.12 m2 Using a Class 2 Effective aerodynamic area vent then the area of the vent needs to be 0.24 m2. This means about 150mm by 800mm air inlet per door width. The outlet size needs to be equal to or greater than the inlet area. 2/04/2007 Page 16 of 17 Signalling Equipment Temperature Control Guideline Bungalows The normal maximum internal heat load for a bungalow is 1000w although an electrical power room with a large UPS could be up to 3000W. Given an aim to limit heat rise in the location to 3ºC due to internal heating and allowing up to 7ºC heat rise due to solar heat gain. For a 3.3m by 5.5m bungalow the calculation is: Q= 0.05 x (1000) / 3 = 16.6 m3/m This equates to a 400mm Edmonds Hurricane Turbine Ventilator rotary roof ventilator in a 6 km/hour breeze under typical conditions. The nominated flow rates for rotary roof ventilators are stated for ideal conditions and actual flow rates are more likely to be around 75% of the stated values. This is based on information provided by CSR Edmonds. Inlet air vents need to be 4 times the throat area of the rotary roof ventilator, which is 4 x π x 0.22 (4 x π x r2) or about 0.5m2. This means effective air inlet of at least 8 off, 250mm by 300mm wall vents and a 600mm by 700mm door vent based on the use of Class 2 Effective aerodynamic area vent. If the heat load is 3000W then a 700mm rotary roof ventilator or 2 off, 500mm rotary roof ventilators are required. The inlet vents required would be 12 off, 250mm by 300mm wall vents, and a 600mm by 900mm door vent. 2/04/2007 Page 17 of 17