What Are the Disadvantages of Heat Recovery Systems?

Heat recovery systems are known for saving energy, improving air quality, and maintaining consistent indoor temperatures. Yet, like any mechanical system, they come with certain limitations that homeowners should understand before deciding to install one.

Across Hampshire, Berkshire, Surrey, and Oxfordshire, many properties now feature Mechanical Ventilation with Heat Recovery (MVHR). When designed and installed correctly, it works quietly and efficiently. When poorly specified or fitted, however, it can cause unnecessary problems.

Understanding both the strengths and weaknesses of MVHR helps ensure you make an informed decision.

Initial Cost

One of the main drawbacks of heat recovery systems is the upfront cost. A full-house installation typically ranges from £3,000 to £8,000, depending on property size and layout.

For large or complex homes, this can be higher due to additional ducting and design work.

Although the investment pays off over time through energy savings, the initial expense can be off-putting for homeowners comparing it to simpler ventilation systems.

Installation Complexity

MVHR systems require ducting throughout the property. This can be straightforward in a new build but more complex in existing homes where access is limited.

Challenges include:

• Finding space for duct routes in older buildings
• Locating suitable positions for ceiling diffusers and wall vents
• Minimising visual impact in finished rooms

Retrofitting can be labour-intensive, particularly if the property has solid ceilings or limited roof voids.

In one project near Guildford, installers had to adapt ductwork design to fit through narrow ceiling cavities. The system still performed well but took longer to install.

Maintenance Requirements

While maintenance is minimal, it is essential. Filters need cleaning or replacement every six months to maintain airflow and efficiency. Neglecting this can cause:

• Reduced air quality
• Higher energy use
• Noise from restricted airflow

Annual servicing ensures the heat exchanger and fans remain clean and balanced.

Homeowners who ignore maintenance may notice reduced performance within a year or two.

Electrical Requirements

MVHR systems require a dedicated electrical power supply, which must be installed and certificated by a qualified electrician. This adds a small cost and coordination step during installation.

Improper wiring or uncertified connections can lead to safety issues or invalidate warranties.

Dependence on Good Insulation

Heat recovery systems perform best in airtight homes. If a property is draughty, much of the recovered heat can escape through gaps and poor insulation.

Before installation, it’s important to assess:

• Wall and roof insulation levels
• Window and door seals
• Air leakage around floorboards or loft hatches

Without this preparation, the system cannot achieve its designed efficiency.

Noise Considerations

Modern MVHR systems are designed to run quietly, but incorrect installation or poor design can cause low-level background noise. This is usually the result of:

• Poorly sized ductwork
• Sharp bends restricting airflow
• Incorrect fan settings

Professional design eliminates these issues by balancing pressure and air velocity.

Space Requirements

The central unit and ducting need physical space. In most homes, this means a section of loft, utility room, or plant cupboard.

For small flats or compact properties, a single-room heat recovery unit may be a better alternative.

Power Consumption

Although MVHR systems are efficient, they still use some electricity to run the fans. This typically costs £40 to £60 per year, but systems left unbalanced or running at high speeds unnecessarily can consume more.

A professional commissioning process ensures optimal performance and minimal energy use.

When Heat Recovery May Not Be Suitable

In some cases, MVHR may not be the right choice:

• Older homes with poor insulation
• Properties where window ventilation is preferred
• Buildings without space for ducting

For these, alternative systems such as positive input ventilation (PIV) or decentralised MVHR may be more practical.

Balancing the Disadvantages

While the disadvantages are real, they can be managed effectively with proper design and installation. A well-fitted system provides far greater benefits than drawbacks.

At ClimateWorks, we install and maintain MVHR systems across Hampshire, Berkshire, Surrey, and Oxfordshire. Each system is designed to meet the property’s structure and performance needs, ensuring value and reliability.

References

• UK Government – Building Regulations Part F
• Energy Saving Trust – Ventilation Guidance
• CIBSE – Heat Recovery Systems in Buildings

Author Bio

Dr Julian Carter is Technical and Compliance Director at ClimateWorks. He has over 25 years of experience in air conditioning, refrigeration, and ventilation, specialising in sustainable and compliant system design. Julian has worked on projects across Hampshire, Berkshire, Surrey, and Oxfordshire, helping homeowners and developers integrate efficient ventilation solutions. As a visiting professor at a UK university, he lectures on building services engineering and indoor environmental quality.

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