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Air Flow Solutions

FLEXI

Frost Protection Used in MVHR equipment to prevent moisture freezing in the heat exchanger and allied parts. Grille A system of fixed or adjustable vanes covering an opening through which air is discharged. Return grille A grille covering an opening through which air is withdrawn from the conditioned space. Heat Exchanger A device designed to efficiently transfer heat from one air stream to another, as in MVHR. At no time does the warm and colder air mix but a Metal or Polypropylene core may be used to transfer heat at different temperatures. IEEE Institute of Electrical and Electronic Engineers Inlet device A shaped air intake with pressure tappings that can be calibrated and used to measure air flow rate (e.g. bellmouthed or conical inlets). IP Rating The degree of protection afforded by a casing against the ingress of solid objects and liquids. Designated by IPXX The first figure is for solid objects rated from 0 (no protection) to 6 (total protection). The second figure is for Liquid from 0 (no protection) to 9 (protection against long periods of immersion under pressure). MEV Mechanical extract ventilation. A description usually applied to a central extract system as defined in System 3 of Approved Document F. MVHR Mechanical Ventilation with Heat Recovery. Equipment to regain warmth from otherwise waste extract air and supply to living spaces providing warm, filtered fresh air. Notifiable Work Activities which require compliance with the Building Regulations, approval by Building Control. Passive House A term referring to a very high standard of energy efficiency in a buildings design and construction. Typically a dwelling would have an air tightness level better than 1.5 m 3 /hr/m 2 Pressure Air pressure The force per unit area imposed on the surface of a solid body by gaseous air. Absolute pressure Pressure relative to a perfect vacuum. Barometric pressure The local ambient air pressure. Differential pressure The difference between pressures measured at two points or levels in a system. Static pressure The difference between the absolute pressure at a point in an air stream or a pressurised chamber and the absolute pressure at ambient temperature. This is positive when the pressure at that point is above ambient pressure, and negative when below. It acts equally in all directions and is independent of velocity. Velocity pressure The increase in pressure produced by bringing a moving airstream to rest (as measured by a pitot static tube). It is equal to the product of air density and the

square of the velocity divided by 2, and is sometimes known as the velocity head or dynamic pressure. RCD A residual current device is a life saving compnent designed to disconnect an electrical circuit when it detects the electrical current is un-balanced. An unbalanced circuit can cause a short circuit to occur causing possible harm and electricution to an individual. Relative humidity The relative humidity of an air/water vapour mixture is the ratio of the vapour pressure existing to the saturated vapour pressure for the same dry-bulb temperature. Expressed as a percentage. SAP Standard Assessment Procedure. An assessment of the energy efficiency and carbon index of a new dwelling. SAP energy ratings are part of the Building Regulations. SBEM Simplified Building Energy Model. A tool used to calculate the energy performance of non-domestic buildings to assist compliance with Approved Document L of the Building Regulations. SELV Safety Extra Low Voltage fans use a 12 or 24volt electrical supply which means that they can be safely installed within a zone 1 area specified by the IEE Wiring Regulations. Specific Fan Power (SFP) The efficiency of a fan may be described by a numerical value calculated by dividing the operating watts (w) by the air flow rate in L/sec at that power. The value is not fixed and will vary with the fluctuating duty/air flow of the fan. ie: A fan operating at 10 watts with an air flow rate of 25 l/sec would have an SFP 0.4 w/L/sec. Standard conditions (STP) The standard temperature and pressure used to define STANDARD AIR, which has a density of 1.2 kg/m 3 (16ºC and 1000 mbar at 55% RH). TER/DER Predictions of Carbon Dioxide emissions in a new dwelling are calculated as a target value. (TER). A dwellings actual, as built, emission rate (DER) is based on all the elements included, i.e: ‘U’ Values, heating, lighting, overheating and fabric construction. DER should not exceed TER or the building will fail under SAP. Terminal One outlet of a ductwork system. Generally the entrance from which air is supplied to a room and the point at which a grille is fixed. ‘U’ Value A measure of the thermal performance of a building envelope. The higher the value the worse the thermal efficiency. Velocity The speed and direction at which an airstream passes a reference point. Usually the direction is implicit, e.g. velocity in a duct or out of a jet. Otherwise the direction should be stated, e.g. 5 knots NNW. Venturi A venturi is used as a means of metering fluid flow, and consists of a combination of converging and diverging tapers, connected by a short straight pipe known as the throat. The flow rate is related to the pressure difference between tappings at the throat and in the upstream pipe. WEEE Waste Electrical and Electronic Equipment directive. Yaw The horizontal angle an instrument makes to the axis of flow. *Note: For guidance only. E&OE

Ventilation with Heat Recovery Improve indoor climate with cleaner, fresher air. Saves money too by recovering lost heat!

CERTIFIED COMPONENT

Passive House Institute ALL PASSIVE HOUSE CERTIFIED

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● 1,100 m³/hr to 3,600 m³/hr ● Off the shelf delivery ● Counter flow exchanger with up to 95% heat recovery ● Designed for schools, offices, retail and leisure facilities ● Ceiling or floor mounted ● Internet connection and BMS ● Low energy, EC fans ● Incorporate into BREEAM assessments

For further information see pages 176 - 187

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