A Guide to MVHR Filters

MVHR filters – what are they and how do they work?

In this guide we’re going to look at what exactly MVHR filters are and what an MVHR system does.

What does MVHR mean and what do MVHR filters do?

MVHR means Mechanical Ventilation with Heat Recovery.

MVHR is a constant source of ventilation which requires filters to remove stale, damp air from a building and replace it with fresh, filtered air. This creates a climate that is comfortable and condensation-free all year round.

How does an MVHR system work?

A balanced heat recovery ventilation system (MVHR) draws fresh air in continually from the outside, which is then filtered, introduced, and withdrawn via a network of ductwork, while also continuously extracting air from the wet rooms within your property (such as kitchens and bathrooms).

Within the heat recovery ventilation unit itself is an air-to-air heat exchanger that uses the heat from the extracted stale air to warm the incoming fresh, filtered air for the habitable rooms in your home – such as living rooms and bedrooms.

In some cases around 96% of the heat generated within your property can be retained.

When there are larger levels of moisture present, the system can be manually or automatically boosted from trickle operation (.e.g. when cooking and bathing).

Some systems also have a summer bypass feature that, when activated, permits the heat to leave the building without going through the air heat exchanger during the summer. This feature can be regulated automatically or manually, depending on the unit specifications.

Why does an MVHR system need filters?

Two filters are required for every MVHR system:

• one for the air intake
• and one for air extraction

These filters prevent dust and other airborne particles and debris from clogging the heat exchanger and fans in the system. There is also a tonne of research to support the idea that MVHR filters enhance indoor air quality in a house.

What do the MVHR filters actually filter out?

MVHR filters enhance indoor air quality because they actively capture particles that travel through the air.

The new filter standard – ISO 16890 – grades filters according to the types and sizes of particles they can catch.

• ISO Coarse
  Typical Particle Matter – Pollen, stone dust or agricultural dust.
  Particle Size – Filtering an average of more than 50% of particles sized 0.3 – 10 μm
• ISO ePM10
  Typical Particle Matter – Larger particles such as sand, fluff, flying seeds or fine hair.
  Particle Size – Filtering an average less than 50% of particles sized 0.3 – 10 μm
• ISO ePM2.5
  Typical Particle Matter – Bacteria, fungal and mould spores, pollen or toner powder
  Particle Size – Filtering a minimum of 50% of particles sized 0.3 – 2.5 μm
• ISO ePM1
  Typical Particle Matter – Viruses, combustion particles, tobacco smoke, nano particles, air-borne sea salt, oil mist
  Particle Size – Filtering a minimum of 50% of particles sized 0.3 – 1 μm

How do I tell if my MVHR filters need replacing?

On your MVHR control panel, there is usually an automated warning light that you can program to turn on when a specific amount of time (for example, three months) has passed.

If you can’t see any light while looking through the filter or if the filter has a decent layer of dust on it, that’s the best indication that it needs to be replaced.

Also, if the MVHR system starts to get noisy, your MVHR filters are past due for replacement. This is because the MVHR system is noisier and has a harder time moving air around the building when its filters are clogged.

How often should I buy MVHR replacement filters?

We recommend checking your filters every 3-6 months depending on frequently your system is in use and the amount of pollution it is working to filter.

If the MVHR filter is installed in a commercial setting with lots of dust then it will need to be replaced more frequently than say, if it is used in the home.

What are the best MVHR filters to use?

We stock the following MVHR filter brands, and recommend them all for their quality:

• Brink MVHR replacement filters
• Envirovent MVHR replacement filters
• Nuaire MVHR replacement filters
• Polypipe MVHR replacement filters
• Titon MVHR replacement filters
• Vent Axia MVHR replacement filters

Why shop with FiltersDirect for your MVHR replacement filters?

You can have full confidence buying from us at Filters Direct as all our air filtration products are manufactured in the UK, with free postage and same-day despatch on all orders placed before 1PM.