Mechanical Ventilation with Heat Recovery (MVHR) Installation

A Mechanical Ventilation Heat Recovery system (MVHR) is a whole-house ventilation system used in modern, airtight buildings. It removes stale, moist air from rooms such as kitchens, bathrooms and utility rooms, then supplies fresh, filtered air to living spaces and bedrooms. The ventilation improves air quality while also protecting the home against condensation and mould.

What makes MVHR different from standard ventilation is the 'HR' part - heat recovery. Instead of simply expelling warmed air outside, the system transfers the heat to the incoming air. That's why homes with MVHR enjoy greater energy efficiency.

MVHR is usually installed in two stages. During first fix, the main unit and ductwork are fitted while the building is open, accessible and watertight and usually before any other services are fitted. During second fix, the visible valves, controls and final connections are completed once the ceilings and walls are finished.

Once the building is dry after plastering, the system is commissioned, meaning the airflow is tested and balanced so that each room receives the right level of ventilation.

MVHR should be considered as early as possible, while electrics, plumbing and other services are being planned. This allows space for ductwork, the main unit, ceiling voids and valve positions to be properly coordinated, avoiding obstacles like steels and stairs.

The main MVHR unit is usually installed in a plant room, utility room, cupboard, garage or loft. The best location depends on the layout of the property, available space, external wall or roof access, and how easily ductwork can be routed through the home. Wherever it goes, it should be accessible for regular filter changes and servicing.

MVHR is ideally fitted to newbuilds because the ductwork needs to be installed in ceilings and walls throughout the house, which all connect to the central unit.

It is possible to install MVHR in existing homes, but it is more difficult, disruptive, expensive and often impractical, unless the house is undergoing a significant renovation that allows the ceilings and floors to be opened up. Older homes are also less airtight, and the more airtight the property is, the more effective MVHR will be too. 

MVHR reduces condensation and mould by continuously extracting moist air from rooms such as bathrooms, kitchens and utility spaces.

It is not a cure for existing damp or building defects, but in a well-designed, well-insulated home, it can play an important role in managing moisture and improving indoor air quality.

A properly designed and installed MVHR system should be almost silent in normal use. Noise problems are more likely when a system has a fault, is poorly designed, undersized, badly installed or not commissioned correctly. This is why system design, duct layout, unit sizing, airflow balancing and servicing all matter.

MVHR is not air conditioning, so it does not actively cool the air. However, all MVHR units that we install at Cinergi include a summer bypass mode, which stops heat from being recovered when it is not needed.

On cooler summer evenings and overnight, the bypass mode can help flush out warm, stale air and bring in cooler, fresher outdoor air, which can make bedrooms and living spaces feel more comfortable.

MVHR can be installed with air conditioning. The two systems do different jobs: MVHR provides continuous ventilation, while air conditioning actively cools the air. MVHR’s summer bypass mode might be enough to improve comfort at night during warmer weather, but air conditioning is preferred for active cooling.

MVHR systems are designed to run continuously at a low background rate and typically use relatively little electricity. Exact running costs depend on the unit, property size, settings and usage.

The main energy benefit is that MVHR reduces the amount of heat lost through ventilation, which can significantly outweigh the electricity it consumes. This is how MVHR helps improve overall energy efficiency and reduces bills in a well-insulated, airtight home.

Efficiency depends on the unit specified, system design and installation quality. High-performance MVHR units can recover up to 96% of heat from extracted air, helping reduce ventilation heat loss.

For best results, the system needs to be correctly sized, installed and commissioned for the property.

MVHR is straightforward to maintain. Filters usually need changing every 6–12 months, depending on the system, location and household needs. Homes with pets, allergies or higher dust levels may need filter changes more often.

We also recommend regular servicing to keep the system clean, efficient and to prolong its lifespan.

Building regulations require homes to have adequate ventilation. MVHR is one way to meet those requirements, and it is often chosen for airtight, energy-efficient homes because it provides controlled ventilation while recovering heat.

It is also almost always specified in Passive House and low-energy projects.

Cinergi installs MVHR systems across the South of England. If you are planning a new build, self-build or high-performance home project, get in touch, and we will let you know whether we cover your area.

VOCs, or Volatile Organic Compounds, are chemicals that evaporate into the air from common household products and materials such as paint, carpets, flooring, cleaning products, aerosols, air fresheners, and some fabrics and furnishings. VOCs can become particularly concentrated in new buildings and new renovations. That noticeable ‘new’ smell is often VOCs being released into the air. At high concentrations, VOCs can contribute to headaches or eye, nose or throat irritation.  

Combining an MVHR and a heat pump is a very efficient solution for both ventilation (to remove moisture and impurities) and heating a home. Both systems also work at their best in well-insulated, airtight properties.

The MVHR system doesn’t generate heat, but it dramatically reduces heat loss from a space that is already warm. This complements the operation of the heat pump, which is designed to work low and slow to provide heat efficiently.

The slower the heat pump needs to replace heat, the more efficiently it can run, which helps you save on your energy bills. However, MVHR does not mean that a smaller heat pump can be fitted. Heat pumps are sized to meet the entire heat loss for a home from the cold, but MVHR will reduce the running costs of heating a home once it is warm.