What is MEV (Mechanical Extract Ventilation)?

How does MEV work?

MEV works by centrally extracting moisture laden and stale air, simultaneously, from multiple wet room (kitchens, toilets, bathrooms) points. The basic units offer a continuously running trickle fan, ensuring the home is always kept free of stale, humid air. Fan speed is set up on install. These basic units can be supplied with a separate switch to perform a boost function when needed. A slightly more convenient solution would be a humidistat sensor version, where the fan will boost upon sensing humidity, for example when taking a shower. The sensor is mounted within the fan unit itself, so there is no need for remote installation. Other features dependent upon your chosen unit, include; air sensors, remote wireless boost switches, digital displays, app control, and CO2 sensors.

We take a look at our most popular MEV systems further below.

Is my house suitable for MEV?

Easy installation of MEV largely depends on the construction of the property or whether you are undertaking a full renovation project. A new build for example lends itself perfectly to an MEV unit, as the design and installation can be planned around the fabric of the building, alongside your other utilities. If you are just refurbishing the upstairs of your home, and there is an accessible loft space, then MEV is likely possible, but you will need to consider joist direction and other obstacles, as this may impede the ducting runs.

<>It is important that the fan chosen is suitable for the size of your home, to ensure maximum performance and efficiency. Ducting length and duct type will of course affect the performance of your fan, which is why we recommend having a system designed and specified. We can of course help with that. Most manufacturers will recommend rigid or semi-rigid ducting, but flexible ducting can also be used successfully.

MEV units are extremely compact, weighing as little as 5kg’s and only 16cm in height. The MEV units we offer can handle up to 1 kitchen + 6 wet rooms, with the higher output of 370 m3/hr units suitable for care homes and student accommodation.

Thankfully, the look of the unit isn’t important, as it will be neatly tucked away in a loft or cupboard space. The only visible part to the homeowner will be the round unobtrusive grill in your kitchen or wet room. Manufacturers do recommend that the unit is positioned to minimise the exhaust (exit) run length of the system.

What are the best MEV Ventilation units on the market today?

At first glance, the number of MEV units on offer can appear confusing but break it down into the requirements for your home or situation, and hopefully, we can help find the right fan for you. For all MEV or MVRH units, we recommend a design and specification to ensure your installation meets building regulations and performs as expected. Please contact us if you need help with this.

Brand leaders Vent-Axia have a strong and proven offering of MEV systems, starting with the Lo-Carbon Multivent, offering 3 speeds and an extraction rate up to 117 l/s. Set up is made easy with the 3 digit LED display and 3 input buttons. The Lo-Carbon Multivent range is completed with a humidity option for added convenience and function.

Next in their range offering is the Sentinel, which is more powerful than the Multivent, and incorporates additional speed controls, of low, normal, boost, and purge. The basic Sentinel model incorporates a built-in humidity sensor, whilst the HX model has the additional benefit of app control and the ability for additional sensors, and controllers. Finally, their CO2 model adds the benefit of a CO2 sensor that detects increased occupancy within a building, thus cleverly triggering the boost function.

Finally, Vent-Axia offers a Sentinel Plus model, in all 3 variations. The plus model is for larger installations, up to 159 l/s.

All Vent- Axia models benefit from the use of an efficient and powerful centrifugal motor designed for 24 hour usage, with a range of sensor and input controllers. Each unit has 3 inputs on the side and one underneath. A Y splitter can be used should you need more inputs than this, up the maximum extraction tolerance. For added peace of mind, all Vent-Axia MEV units come with a 7-year guarantee.

Envirovent also offers an excellent range of affordable MEV units.

The original OZEO is capable of accepting 4 inputs for up to 6 wetrooms, and like all models is designed for low energy continuous running, to maintain a healthy environment air quality. The beauty of the OZEO unit is the flexibility of the inlets, which can all be pivoted 90 degrees, to suit the incoming duct runs. Furthermore, the exhaust can be pivoted fully 360 degrees, allowing for vertical or horizontal mounting on walls or ceilings. The unit is also supplied with a remote control boost function for when extra power is required. For a more automatic operation with a higher performance spec, we recommend considering the MEV humidity sensing units below.

Envirovent has also developed a feature packed MEV unit, capable of serving up to 1 kitchen and 6 wet rooms in the home, whilst delivering up to 75 l/s. The compact dimensions of these units makes them perfect for installations where space is at a premium, offering both vertical and horizontal mounting. For the installer, the speed of installation is further enhanced if the Fast Track ducting range is used, but the units can also be connected to standard ducting.

When in use, the MEV160 unit runs at a constant low level, ensuring an all year round consistent air quality, with its super efficient DC motor and backwards centrifugal fan. The inbuilt Humidity tracker provides constant air monitoring, boosting as required, but for added convenience, the unit can be connected via a wired boost button or wireless remote control. For those situations requiring the monitoring of air quality, the units can be connected to the AirSens IAQ sensors, with their traffic light system, of Red, Amber, Green. The MEV160 will react automatically to changes in air quality, maintaining a healthy environment.

Moving up in output, and suiting those larger houses and communal residences, such as care homes, Envirovent also offers the MEV300. The MEV300 provides airflow rates up to 103 l/s (370 m3/hr), whilst retaining the same 16cm height profile as the less powerful model.

Monsoon MEV

National Ventilation offers a fantastic MEV range under their Monsoon brand. The MEVDC400 & MEVDC/H400 are compact units measuring only 391mm square making them ideal solutions for tight spaces.

The Monsoon MEV features an efficient and powerful energy-efficient centrifugal DC motor specifically designed for continuous running. The two-speed motor extracts 88m3/h 24 litres per second on its trickle setting and boosts 425m3/h 118 litres per second.

The MEVDC/H400 features an inbuilt humidity sensors which trigger the boost function whereas the MEVDC400 relies on an external switch or sensor such as PIR. They have been developed in a way that allows them to be wall, ceiling or loft mounted and feature four 125mm extract points and condensation drains.

In summary, you can see that all the units above essentially perform the same function, but with differing benefits, features, outputs and warranty. If you need more help with your system, do not hesitate in contacting a member of our sales team.