Mechanical Ventilation with Heat Recovery


Positive Input Ventilation


Mechanical Extract Ventilation

Choosing the best Mechanical Heat Recovery Ventilation System

As independent MVHR installers (Mechanical Ventilation System with Heat Recovery), we are not contracted to any specific manufacturer or model. We are committed to sourcing the most up to date, energy efficient heat recovery ventilation system currently available on the market, one that is SAP Appendix Q listed and Energy Saving Trust best practice compliant.

Our team of skilled engineers have experience in all types of installation, from single unit whole house heat recovery ventilation to large scale commercial air handling units.

We can provide a high quality, energy efficient ventilation system that is tailored specifically to your needs. Based in Co. Tyrone in Northern Ireland, we are able to design, install and commission mechanical ventilation systems with heat recovery all over Ireland.

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The MVHR unit

We recommend installing MVHR units with in-built cross counter-flow heat exchangers. The heat exchange efficiencies are much higher (up to 90%) and the operating costs are much lower (0.4 W/l/s) compared to that of cross-flow or rotary wheel heat exchangers.

A cross counter-flow heat exchanger transfers heat from one air-stream to another. At its core is a stack of plastic plates, within which are a series of airflow channels. 

These channels are aligned precisely to ensure that heat from the extracted warm is transferred to the cooler incoming supply air. Unlike a rotary heat exchanger, a cross counter-flow heat exchanger does not exchange humidity and there is no risk of mixing the air-streams. It is typically used in buildings where hygienic standards require that both air streams are kept completely separate from one another.

This technology is designed to deal with large volumes of warm moist air, thus enabling us to position extract air valves directly over shower enclosures. By extracting steam at its most intense point we can dramatically reduce condensation levels whilst recover the highest possible temperature from the warm air before extraction to the outside.

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The Ducting system

It is important to remember that the heat exchanger is only one part of the entire ventilation system. Choosing the correct ducting and installing it properly will significantly improve the performance of any heat recovery ventilation unit, regardless of the type of heat exchanger selected.

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The reason being; warm air extracted from a wet room (e.g. kitchen, bathroom etc.) must travel through the ductwork to reach the heat exchanger.

Fresh incoming air passing through the heat exchanger must travel through the ductwork before terminating in a habitable room (e.g. living room, bedroom etc.) If this ductwork has been poorly insulated, little to no heat energy will be recovered.

Careful consideration should be given to the location and positioning of ductwork so as to limit airflow restriction. By limiting restriction, the fan motors can run slower, hence the power consumption will be reduced. We recommend installing rigid thermal ducting throughout non-conditioned areas and rigid PVC ducting within the heated envelope.


Mechanical Extract Ventilation (MEV)

The MEV system incorporates a low energy, high efficiency fan unit which is ducted via multiple air inlets to each wet room in the house, where a ceiling valve acts as the point of extraction. The MEV unit is designed to operate continuously at low speed without occupant intervention. However various control options are available including switches/ sensors that can instruct the system to boost when required e.g. to remove cooking smells or condensation. Typical controls include humidistats, lighting circuits, shower circuits, motion (PIR) sensors, and manual boost switches.

This is a centralised extract system designed to ventilate your entire property without the need for individual extractor fans. Stale moist air is continuously extracted from the wet rooms (e.g. Kitchen, Bathroom etc.) and discharged to the outside via a single fan unit. The extraction of air within each of the wet rooms creates negative pressure within the property, causing fresh air to be drawn in via background ventilators e.g. trickle vents in the habitable rooms.

Installation Process

It is really only practical to install continuous Mechanical Extract Ventilation (MEV) in a new build or during a major refurbishment. We will supply, install and commission the MEV unit and associated ductwork at the first fix stage of the project. The MEV unit is typically mounted in the loft space, but it is small enough to be fitted with in ceiling void or cupboard if necessary. It is necessary to provide a 10mm gap at the bottom of all internal doors to allow the free passage of air through the property.


Benefits of a MEV system
  • Low-carbon ventilation strategy that complies with the Building Regulations and is SAP Appendix Q recognised.
  • Ultra-quiet and efficient ventilation unit. The latest technology in low-watt DC fans provides quiet operation, with reduced power consumption, operating costs and life cycle costs.
  • Low watt motors provide high performance extract ventilation (i.e. up to 98 l/s)
    Low profile unit (i.e. 190mm deep) can be mounted in any orientation offering a flexible hassle free installation
  • ABS moulded case and lid provides added strength for a more robust unit.
  • Full 5 year manufactures warranty.
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