5 Common Mistakes When Installing an MVHR Unit and Their Solutions
If you’re looking for an effective and energy-efficient upgrade to your home's air and filtration system, look no further than a Mechanical Ventilation with Heat Recovery (MVHR) system. By continuously supplying fresh, filtered air and recovering heat from the stale extracted air, MVHR units improve indoor comfort whilst dramatically reducing energy waste.
However, the system’s performance depends heavily on correct design, installation and commissioning. Even small mistakes during installation can cause immediate problems and lead to ongoing maintenance issues.
At BPC Ventilation, we help both commercial and domestic clients across Northern Ireland, the UK, and Ireland who are looking to improve their natural ventilation. Read on as we explore five of the most common installation issues encountered on site and how to prevent them for a reliable, high-performing MVHR ventilation system.
1. Poor Ductwork Design and Layout
The ductwork network is the heart of the MVHR system, carrying fresh air to living spaces and extracting stale air from wet rooms. Correct design and installation are paramount; otherwise, it can compromise the entire system’s performance. Long duct runs; sharp bends and sudden diameter changes all create resistance that reduces airflow and increases fan noise.
To achieve consistent and balanced ventilation, ducting should always be as short and straight as possible, with smooth internal surfaces and gentle bends.
A well-planned layout during early construction stages can prevent later compromises that are difficult and expensive to fix once ceilings or floors are closed.
The use of Semi Rigid ductwork in the design will provide a quitter and more efficient system
2. Incorrect Positioning of the MVHR Unit
Ideally, the unit should be positioned in a centralised spot that’s both easy to access and temperature-stable - such as a plant room for domestic buildings, utility space or an insulated loft enclosure for homes. This allows shorter duct runs and easier maintenance access. At least 600mm of clearance should be provided around the unit to make filter changes and servicing straightforward.
It’s also important to mount the unit on a solid wall or frame to minimise sound transmission through the structure. A correctly located and supported unit will operate quietly and competently for years to come.
3. Inadequate Airtightness and Duct Sealing
Air leakage is a common and incredibly costly installation error in MVHR systems. Even small gaps at duct joints can lead to substantial efficiency losses, as valuable heat is lost through leaks before it reaches supply areas. Leaks also cause air imbalance, where some rooms begin to receive too much air while others receive too little, which will quickly lead to discomfort.
If using solid rigid ducting every joint, connection and fitting should always be sealed using appropriate airtight tapes and seals designed for ventilation systems.
The use of semi rigid ducting provides a superior air tightness as there are minimum joins and use rubber seals
4. Poor Balancing and Commissioning
An MVHR system must be balanced correctly to function as designed. If supply and extract airflows are not properly adjusted, the home can experience noise or poor air quality. Unfortunately, skipping or rushing the commissioning stage is a common mistake that limits system performance right from day one.
During the commissioning stage with each room’s airflows are measured using calibrated equipment and adjusted via air valves to achieve the specified rates. This ensures that every space receives the right amount of ventilation and that the overall system remains balanced. Filters and fans are also checked for correct operation at this stage, and controls will be set to match occupancy patterns and building type.
A properly commissioned MVHR ventilation system with BPC Ventilation will run quietly, recover maximum heat and always provide consistent comfort across all rooms.
5. Neglecting Maintenance and Filter Access
Even the best-installed MVHR unit will suffer over time if filters are not maintained. Dirty filters restrict airflow, performance and can increase noise and wear on the fans. Unfortunately, filters are sometimes difficult to access because the installer didn’t allow enough space or failed to consider maintenance during the design stage.
Good installation practice means positioning the unit so filters can be easily removed and replaced without dismantling ducting or panels. Regular maintenance - typically every 12 months but could be every six months or more in dusty environments - ensures the system continues to deliver clean, balanced air and maintains its energy recovery performance.
After working with our team of installation experts at BPC Ventilation, businesses and homeowners are shown how to inspect and replace filters as part of the handover process.
BPC Ventilation: Specialists You Can Rely On
Choosing to invest in an MVHR unit is a wise step towards better comfort, energy efficiency and indoor air quality. When installed correctly, it will provide you with many years of quiet, trouble-free operation and measurable energy savings. The key is attention to detail - from ducting design and positioning to airtight sealing, proper commissioning and accessible maintenance.
By working with a reputable partner, such as BPC Ventilation, who’ll avoid these common installation mistakes, you can take comfort in the fact that your MVHR ventilation system will perform exactly as intended - sustainably and efficiently. Find out more about our MVHR systems on our website today, or contact a member of our team to discuss further.
