SAFEXE LTD Gas, Plumbing & Heat Pumps recently attended an MVHR fault diagnosis job in Exeter city centre on a Nuaire MRXBOX mechanical ventilation with heat recovery system.
The main issue found during the visit was heavily blocked filters. The end users also had not been properly educated by the original installers on how the MVHR system works, what it is designed to do, and what basic maintenance is required to keep it running correctly.
This is something we come across fairly often with MVHR systems. The unit may be installed, but if the system is not commissioned properly, explained clearly, and maintained regularly, it may not perform as it should.
✅ What is an MVHR system?
MVHR stands for Mechanical Ventilation with Heat Recovery.
It is designed to provide controlled ventilation throughout a property by extracting stale, moist air from rooms such as bathrooms, kitchens and utility areas, while bringing fresh filtered air into living spaces and bedrooms.
As the stale air leaves the property, the MVHR unit recovers heat from that outgoing air and transfers it to the incoming fresh air where possible. This helps reduce heat loss while improving indoor air quality.
An MVHR unit is not air conditioning. It will not rapidly cool a property like an air conditioning system. Its purpose is ventilation, moisture control, heat recovery and improved air quality.
🔧 Blocked MVHR filters can cause problems
On this Exeter job, the filters were heavily blocked. Blocked MVHR filters can lead to:
Reduced airflow
Poor ventilation performance
Increased noise from the unit
Lower heat recovery efficiency
Stale air remaining in the property
Moisture and humidity issues
The MVHR system working harder than necessary
Filters are one of the most important basic maintenance items on any MVHR system. If they are left too long, the system cannot move air properly and the benefits of the installation are reduced.
🧰 MVHR fault diagnosis and user guidance
During this visit, we checked the Nuaire MRXBOX system, inspected the filters, assessed the operation of the unit and explained to the end users what the system is designed to do.
We advised that the filters should be replaced and discussed the possibility of recommissioning the system at a later date if airflow readings and balancing are required.
Recommissioning may be needed where a system has not been set up correctly, where the property use has changed, or where airflow rates need checking against the design and the rooms being served.
✅ Why correct MVHR installation and commissioning matters
A good MVHR installation is not just about fitting the unit and ductwork.
The system should be:
Designed correctly
Installed neatly
Ducted properly
Commissioned with airflow readings
Balanced to suit the property
Handed over clearly to the end user
Maintained with regular filter changes
If the homeowner or tenant is not shown how the MVHR works, it is very easy for filters to be forgotten, settings to be misunderstood, and performance to drop over time.
📍 MVHR servicing and fault diagnosis in Exeter and East Devon
SAFEXE LTD Gas, Plumbing & Heat Pumps carry out MVHR servicing, MVHR fault diagnosis, ventilation checks and recommissioning across Exeter, Exmouth, Sidmouth, Budleigh Salterton, Ottery St Mary, Honiton, Topsham, Lympstone, Pinhoe, Exminster, Newton Poppleford, Otterton, East Budleigh and surrounding East Devon areas.
We also work on heating systems, boilers, heat pumps, air conditioning, plumbing, bathrooms and indoor air quality improvements.
For MVHR repairs, ventilation servicing or fault diagnosis in Exeter and East Devon, contact SAFEXE LTD Gas, Plumbing & Heat Pumps.
📞 01395 489981
📱 07850 260101
📧 info@safexe.co.uk
🌐 www.safexe.co.uk