DIY MVHR: Can You Install an MVHR System Yourself?

A practical guide to DIY MVHR installation, including system planning, ductwork, unit selection, common mistakes and support available from BPC Ventilation.

DIY MVHR: Can You Install an MVHR System Yourself?

If you are building your own home, renovating a property or simply want more control over your ventilation project, DIY MVHR can be a practical option.

MVHR, or Mechanical Ventilation with Heat Recovery, continuously extracts stale, moisture-laden air from areas such as kitchens, bathrooms and utility rooms while supplying fresh filtered air to bedrooms and living spaces. As the two air streams pass through the MVHR unit, heat from the outgoing air is recovered and used to temper the incoming fresh air.

Although an MVHR system needs to be properly designed, installed and commissioned, much of the physical installation can be completed by a competent self-builder or DIY installer. The key is getting the system design right before ductwork starts going into the property.

At BPC Ventilation, we can support DIY MVHR projects from the initial design stage through to installation, with free system design, instant online quotations and dedicated technical support.

Can You Install MVHR Yourself?

For many self-builders and experienced DIYers, the answer is yes.

A DIY MVHR installation can involve installing the ductwork, distribution boxes, plenums, air valves and the MVHR unit itself according to an agreed system layout. However, DIY should not mean guessing your way through the design.

Airflow requirements, MVHR unit sizing, duct lengths, pressure resistance, valve locations, external intake and exhaust positions and system balancing all affect how well the finished system performs.

Electrical connections, commissioning or other specialist work may also need to be completed or checked by an appropriately qualified or competent person depending on the system and the regulations applicable to your project.

For projects in England, the government's Approved Document F provides guidance on ventilation requirements for dwellings. Requirements vary throughout the UK and Ireland, so you should always check the regulations applying to the location of your project.

How Does a DIY MVHR System Work?

A whole-house MVHR system normally uses two separate groups of air valves.

Extract valves remove humid or stale air from wet rooms such as bathrooms, kitchens, ensuites, WCs and utility rooms. Supply valves introduce fresh filtered air into habitable spaces such as bedrooms, living rooms and home offices.

These ducts run back to the central MVHR unit, where heat is transferred between the outgoing and incoming air streams without directly mixing them.

For a DIY installation, the principle is straightforward. The more important part is making sure each component has been selected and positioned as part of a complete ventilation design rather than treating the MVHR unit and ductwork as separate products.

You can also read BPC's guide to home ventilation ductwork for more information on ducting systems used within MVHR installations.

What Do You Need to Plan Before Installing DIY MVHR?

Before starting an MVHR installation, you should consider:

MVHR unit sizing: the unit needs to provide the required airflow for the size and layout of the property at a sensible operating point, rather than simply being chosen on its maximum advertised airflow.
Supply and extract locations: each room should be assessed to determine whether it requires supply air, extract air or neither.
Duct routes: ductwork should be planned early to avoid unnecessary bends, excessively restrictive routes and clashes with other building services.
Distribution boxes and plenums: radial systems normally distribute individual duct runs from central manifolds to room terminals.
External intake and exhaust terminals: these need suitable positions and separation to minimise the chance of extracted air being drawn back into the system.
Access and maintenance: the MVHR unit, filters and other serviceable components should remain accessible after the property is complete.

Planning these elements before installation is much easier than trying to correct an unsuitable duct route or valve position after ceilings and walls have been finished.

Start With a Free MVHR Design From BPC Ventilation

You do not have to design a DIY MVHR system from scratch.

If you already have architectural or floor plans, you can send them to the BPC Ventilation design team for a free MVHR estimate and layout guide.

The design service includes room-by-room airflow figures, valve requirements and guidance on unit location, valve positions and intake/exhaust routes. This makes it particularly useful for self-builders who want to carry out the installation themselves but still want the system planned around the individual property.

Need a Price Quickly? Use the MVHR Instant Quote

If you are still at the budgeting or early planning stage, you can also use the BPC Ventilation Instant Quote and Kit Builder.

Enter information including the floor area, bedrooms, living rooms and wet rooms, and the tool can provide an instant MVHR estimate based on the property details. It can recommend a system and build a material list and price, making it useful for getting an initial idea of what a DIY MVHR project may require.

For more unusual properties, complex layouts or projects where drawings are available, the free design service is the better option.

Choosing the Right MVHR Unit

The MVHR unit is at the centre of the system, but bigger is not automatically better.

Unit selection should take account of the required airflow, property size, expected system resistance, installation location, controls, noise and the type of ductwork being used.

BPC Ventilation stocks domestic MVHR units from manufacturers including Vent-Axia, Zehnder, Mitsubishi, Nuaire, Domus, Duco, Komfovent, Airflow and others, providing options for different property sizes and installation requirements.

Common DIY MVHR Installation Mistakes

One of the biggest mistakes with a DIY MVHR project is focusing entirely on the unit while treating the ductwork as an afterthought.

Restrictive duct routes, unnecessary bends, incorrectly positioned valves and poor system balancing can all prevent a good MVHR unit from operating as intended. Similarly, choosing a unit solely because its maximum airflow appears large enough does not account for the resistance created by the completed duct system.

The installation should therefore follow the system design, manufacturer instructions and applicable ventilation requirements.

Once installed, the system should also be correctly commissioned and balanced so that the required supply and extract airflow rates are achieved.

Technical Support for Your DIY MVHR Installation

Choosing DIY does not mean you are left without support once the equipment arrives.

BPC Ventilation provides dedicated technical support for MVHR systems, including help with ducting, airflow, controls, product identification and initial troubleshooting. More specialist issues involving commissioning, wiring or internal faults can be escalated for further technical support where required.