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MVHR Filters in Ireland – Maintenance, Change Schedule and Resets
MVHR filters control air quality and how hard the unit has to work. Especially airtight or NZEB houses, dirty filters can quickly lead to poor ventilation, higher humidity and noisy fans.
This guide explains:
- what MVHR filters do,
- how often to change Vent Axia filters Ireland homeowners use,
- what a Vent Axia check filter message really means, and
- how to carry out a safe Vent Axia filter reset after replacement.
What do HRV filters actually do?
Most MVHR (heat recovery) units use at least two core filters:
- Supply filter – cleans outdoor air before it enters the home.
- Extract filter – protects the unit from indoor dust, fibres and general household debris.
Together, these filters:
- protect your lungs by reducing fine dust and pollen entering bedrooms and living rooms,
- protect the heat exchanger and fans from dust build-up,
- keep designed airflow rates closer to what was specified at commissioning.
Good filtration means better indoor air quality and a longer life for the MVHR unit.
How often should you change Vent Axia filters in Ireland?
Irish conditions vary hugely between a quiet coastal site and a busy urban road. As a simple baseline for Vent Axia filters Ireland:
- Check MVHR filters every 3 months.
- Replace every 6–12 months under normal conditions.
You should shorten the interval if you have:
- nearby farms, trees or heavy pollen,
- a busy road or lots of dust from traffic,
- pets inside the home,
- ongoing building works or renovations.
There is no single schedule that fits all homes. Treat the manufacturer’s recommendation as a starting point and adjust based on what you see when you open the unit.
Signs your HRV filters are clogged (do not wait for alarms)
Do not rely only on controller messages. Watch for physical signs that MVHR filters are overdue:
- weaker airflow at supply terminals,
- rising indoor humidity compared with previous months,
- more condensation on windows or in bathrooms,
- increased fan noise as the unit strains to move air,
- visible dust build-up on supply valves and grilles.
If you notice these symptoms, change the filters first, then reassess performance. It is one of the quickest and cheapest fixes you can try.
Vent Axia check filter message – what does it mean?
A Vent Axia check filter message is usually time-based, not a precise blockage sensor. The controller counts hours of operation and reminds you to inspect and replace filters.
That means:
- do not assume the filters are fine just because airflow “feels okay”,
- do not simply clear the message without opening the MVHR unit,
- always physically inspect the filters and replace them if there is visible dust, discolouration or damage.
Treat the check filter message as a prompt to carry out proper maintenance, not as an annoyance to dismiss.
Vent Axia filter reset – when and how to do it
A Vent Axia filter reset should only be done after new filters are installed:
- Switch off the unit according to the manufacturer’s safety instructions.
- Open the cover and remove the old filters carefully to avoid spreading dust.
- Insert the new filters, making sure they face the correct direction and sit fully in their frames.
- Close the unit and power it back on.
- Use the controller or app to perform the filter reset (follow the exact steps for your model).
If you reset the timer without changing filters, you lose accurate tracking and risk running clogged filters for far too long.
Can you clean filters instead of replacing them?
Sometimes, but only if the manufacturer allows it.
- Many filters are not washable – washing can damage the media and reduce filtration performance.
- If cleaning is allowed, it is usually limited to gently hoovering the surface or carefully rinsing with water.
Always:
- follow the manufacturer’s instructions,
- let any washable filters dry fully before reinstalling,
- replace filters immediately if the media looks thin, torn or deformed.
Cheap “cleaned for another year” filters may save a few euros but reduce protection for both the unit and the occupants.
Why filters affect humidity and condensation
Clogged filters restrict airflow. The unit may still run and appear normal on the controller, but the actual volume of air moved through the house drops.
Lower airflow means:
- moisture from showers and cooking stays indoors longer,
- RH rises, especially in bathrooms and bedrooms,
- condensation and mould risk increases on cooler surfaces.
Regular filter maintenance is therefore one of the cheapest ways to protect comfort, health and building fabric.
Simple and reliable filter replacement strategy
A practical approach for Irish homeowners:
- Keep one full spare filter set on site at all times.
- Replace both supply and extract filters together unless the manufacturer says otherwise.
- Record the date in the controller, app and on the filter box with a marker.
- Book a professional ventilation service every 12–24 months, especially after renovation or decoration works.
- Consider an airflow test if humidity or comfort problems persist even after you change filters.
Clean filters are the foundation. If issues remain, it is time to look at balancing, ductwork and overall system design.
Compliance note – why filters matter for Irish regulations
Effective ventilation helps meet the intent of Irish Building Regulations Part F by:
- controlling moisture to reduce condensation and mould,
- maintaining adequate indoor air quality.
Maintaining airflow with clean filters supports both occupant health and building fabric protection. In airtight homes, ignoring filters can quickly undermine the performance promised at design and commissioning stage.
FAQ – Heat Recovery Ventilation filters and Vent Axia messages
How often should I check heat recovery filters?
A 3-month visual check is a reliable routine for Irish homes. During renovations, or in very dusty or high-pollen locations, you may need to inspect filters more often.
Why does humidity rise when filters clog?
When filters clog, airflow drops. Moist air from showers, cooking and laundry stays indoors for longer, so relative humidity rises and condensation becomes more likely.
Should I buy cheap third-party hrv filters?
Some third-party filters work well, but poor fit or weak frames can allow air to leak around the media instead of through it. Always choose high-quality, correctly sized replacements and avoid any filter that does not sit snugly in the frame.
What should I do when I see a Vent Axia check filter message?
Treat a Vent Axia check filter message as a maintenance reminder:
- Open the unit and inspect the filters.
- Replace them if they show visible dust or degradation.
- Carry out the Vent Axia filter reset only after new filters are installed.