{"id":4878,"date":"2026-09-27T08:32:31","date_gmt":"2026-09-27T08:32:31","guid":{"rendered":"https:\/\/mywarmhome.co.uk\/stage\/?page_id=4878"},"modified":"2026-09-29T09:51:25","modified_gmt":"2026-09-29T09:51:25","slug":"mvhr","status":"publish","type":"page","link":"https:\/\/mywarmhome.co.uk\/stage\/mvhr\/","title":{"rendered":"MVHR"},"content":{"rendered":"\n
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VENTILATION \/ MY WARM HOME<\/p>\n\n\n\n

Mechanical ventilation with heat recovery.<\/h1>\n\n\n\n

Continuous fresh air, with heat transferred from outgoing air to incoming air.<\/p>\n<\/div>\n<\/div><\/div>\n\n\n\n

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01<\/p>\n\n\n\n

Understand<\/h3>\n\n\n\n

Balanced mechanical supply and extract.<\/p>\n<\/div>\n\n\n\n

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02<\/p>\n\n\n\n

Follow the air<\/h3>\n\n\n\n

Separate air streams meet at the heat exchanger.<\/p>\n<\/div>\n\n\n\n

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03<\/p>\n\n\n\n

Recover the heat<\/h3>\n\n\n\n

Benefits, efficiency and limitations.<\/p>\n<\/div>\n\n\n\n

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04<\/p>\n\n\n\n

Design & check<\/h3>\n\n\n\n

Airtightness, ducts, controls and commissioning.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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THE SHORT VERSION<\/p>\n\n\n\n

Ventilation with less heat lost.<\/h2>\n<\/div>\n\n\n\n
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Mechanical ventilation with heat recovery (MVHR) continuously extracts stale, moist air from wet rooms and supplies filtered outdoor air to living rooms and bedrooms.<\/p>\n\n\n\n

Before outgoing air leaves the building, a heat exchanger transfers some of its warmth to the incoming air. In a typical plate heat exchanger the air streams remain separate: heat moves across the exchanger surfaces without the two flows normally mixing.<\/p>\n\n\n\n

MVHR is not a replacement for heating and is not the same as a heat pump. Its purpose is to deliver reliable fresh air while reducing ventilation heat loss. The unit, ductwork, airtightness, controls, commissioning and maintenance must all work together.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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01 \/ BALANCED SUPPLY & EXTRACT<\/p>\n\n\n\n

Four parts of the same system.<\/h2>\n\n\n\n

Unlike extract-only MEV, MVHR mechanically moves air both into and out of the home. It normally runs continuously at background speed and increases to boost during high-moisture activities.<\/p>\n\n\n\n

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01<\/p>\n\n\n\n

Supply air<\/h3>\n\n\n\n

Filtered outdoor air is delivered to habitable rooms, normally bedrooms and living spaces.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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02<\/p>\n\n\n\n

Extract air<\/h3>\n\n\n\n

Stale air is drawn from kitchens, bathrooms, utility rooms and other designated wet rooms.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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03<\/p>\n\n\n\n

Heat exchanger<\/h3>\n\n\n\n

A core transfers heat from outgoing air to incoming air without normally mixing the air streams.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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04<\/p>\n\n\n\n

Exhaust & intake<\/h3>\n\n\n\n

Separate outdoor terminals, filters and ductwork complete the two air paths.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

MVHR is designed as a balanced whole-house system. Standard background trickle vents are not normally the planned supply route; suitability of existing openings and purge ventilation must be assessed as part of the complete design.<\/p>\n<\/div>\n\n\n\n

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02 \/ FOLLOW THE AIR<\/p>\n\n\n\n

How does MVHR work?<\/h2>\n<\/div>\n\n\n\n
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MVHR has two separate mechanical air streams. The exchanger recovers heat from the exhaust stream before it leaves the building.<\/p>\n\n\n\n

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01 \/ Fresh air enters<\/h3>\n\n\n\n

The supply fan draws outside air through an appropriately positioned intake and a filter.<\/p>\n<\/div>\n\n\n\n

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02 \/ Warm, moist air is extracted<\/h3>\n\n\n\n

A separate fan collects stale air from the wet rooms through the extract duct network.<\/p>\n<\/div>\n\n\n\n

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03 \/ Heat transfers across the core<\/h3>\n\n\n\n

Warm outgoing air passes one side of the heat exchanger; colder incoming air passes the other. Heat transfers across the separating surfaces.<\/p>\n<\/div>\n\n\n\n

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04 \/ Tempered air is supplied<\/h3>\n\n\n\n

Filtered, pre-warmed air passes through supply ducts to bedrooms and living rooms; extracted air is discharged outdoors.<\/p>\n<\/div>\n\n\n\n

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05 \/ Moisture is managed<\/h3>\n\n\n\n

Condensate produced within the unit must discharge safely through a correctly detailed drain, with frost protection where required.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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03 \/ HEAT RECOVERY EXPLAINED<\/p>\n\n\n\n

What exactly gets recovered?<\/h2>\n<\/div>\n\n\n\n
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The outgoing air has already been warmed by the home. MVHR recovers some of that thermal energy rather than sending it all straight outdoors.<\/p>\n\n\n\n

The core transfers heat, not free heating.<\/h3>\n\n\n\n

If it is colder outside than indoors, incoming air can leave the exchanger warmer than the outdoor temperature. The system still needs an effective heating source to maintain the room temperature, and both fans consume electricity.<\/p>\n\n\n\n

Efficiency depends on the real installation.<\/h3>\n\n\n\n

The product\u2019s tested heat-recovery figure is not a guaranteed whole-house seasonal saving. Actual performance depends on airflow balance, insulation and airtightness of ducts, unit location, external temperatures, filters, controls and how the occupants use the system.<\/p>\n\n\n\n

Summer bypass and frost protection<\/h3>\n\n\n\n

Many units can bypass heat recovery when conditions suit, reducing unwanted heat transfer. This is not mechanical air conditioning and cannot by itself guarantee a cool home. Frost protection and condensate arrangements also need to be designed for the unit and climate.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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THE EQUIPMENT<\/p>\n\n\n\n

The unit is only part of the installation.<\/h2>\n\n\n\n
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Select supply and extract terminals for their room duties, with a quiet unit, accessible filters, appropriate outdoor intake and exhaust positions, insulated cold-side ducts and a suitable condensate connection.<\/p>\n\n\n\n

A system can have an impressive headline recovery rating but perform poorly when ductwork is leaky, crushed, inadequately insulated or badly balanced.<\/p>\n<\/div>\n\n\n\n

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03 \/ THE BENEFITS<\/p>\n\n\n\n

Continuous air change with heat recovery.<\/h2>\n<\/div>\n\n\n\n
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In the right building, MVHR combines consistent ventilation with lower heat loss than an otherwise comparable extract-only arrangement.<\/p>\n\n\n\n

Filtered outdoor supply air<\/h3>\n\n\n\n

Fresh air can be filtered before it reaches bedrooms and living areas. Filter selection and regular replacement matter.<\/p>\n\n\n\n

Moisture and pollutant removal<\/h3>\n\n\n\n

Wet rooms have planned continuous extract, with boost available for cooking and bathing.<\/p>\n\n\n\n

Reduced ventilation heat loss<\/h3>\n\n\n\n

Heat from outgoing air is transferred to the incoming supply, reducing the heating energy needed to temper that fresh air.<\/p>\n\n\n\n

Less dependence on windows for background ventilation<\/h3>\n\n\n\n

The normal background air-change route is controlled mechanically. Openable windows or other suitable purge ventilation are still useful and may be required.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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03 \/ KNOW THE LIMITATIONS<\/p>\n\n\n\n

What needs careful consideration?<\/h2>\n\n\n\n
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01<\/p>\n\n\n\n

Airtightness<\/h3>\n\n\n\n

Uncontrolled leakage can bypass the designed system and weaken heat-recovery benefits.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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02<\/p>\n\n\n\n

Duct space<\/h3>\n\n\n\n

Separate supply and extract duct networks need routes, suitable terminals and access, which may be disruptive in retrofit.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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03<\/p>\n\n\n\n

Maintenance<\/h3>\n\n\n\n

Filters need checking and changing; dirty ducts, grilles and cores can reduce performance.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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04<\/p>\n\n\n\n

Noise & energy<\/h3>\n\n\n\n

Two fans use electricity. Poorly sized ducts, badly located units or excessive speeds can create unwanted noise.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

Condensate must drain correctly, cold ducts need appropriate insulation and the installer must account for frost protection, summer controls and access for ongoing maintenance.<\/p>\n\n\n\n

Ventilation alone does not diagnose condensation, mould or damp. Leaks, thermal bridges, heating patterns and other building defects may need separate investigation.<\/p>\n<\/div>\n\n\n\n

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03 \/ COMPARE THE OPTIONS<\/p>\n\n\n\n

MEV, intermittent extract or MVHR?<\/h2>\n<\/div>\n\n\n\n
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There is no automatic winner. Assess the whole home, rather than choosing a fan by its brochure efficiency.<\/p>\n\n\n\n

Natural and intermittent ventilation<\/h3>\n\n\n\n

Air change is provided through openings and fans operating when needed. Performance can depend more on wind, temperature and occupant use.<\/p>\n\n\n\n

MEV \u2014 mechanical extract ventilation<\/h3>\n\n\n\n

Continuous extract removes air from wet rooms, and replacement air enters through designed background ventilators. It does not normally recover heat.<\/p>\n\n\n\n

MVHR \u2014 mechanical ventilation with heat recovery<\/h3>\n\n\n\n

Balanced mechanical supply and extract are linked through a heat exchanger. It can reduce ventilation heat loss, but needs a suitable level of airtightness and space for two duct routes.<\/p>\n\n\n\n

The choice must also consider any open-flued or other combustion appliances, existing vents, fabric condition, household needs and the wider retrofit plan.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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04 \/ DESIGN, COMMISSION, MAINTAIN<\/p>\n\n\n\n

Eight checks for effective MVHR.<\/h2>\n\n\n\n
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01<\/p>\n\n\n\n

Assess the whole dwelling<\/h3>\n\n\n\n

Record airtightness, occupancy, moisture loads, room usage, existing ventilation, building condition and combustion appliances.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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02<\/p>\n\n\n\n

Set the room-by-room airflow<\/h3>\n\n\n\n

Design appropriate continuous and boost rates, then size supply and extract terminals and fan duties.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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03<\/p>\n\n\n\n

Plan both duct routes<\/h3>\n\n\n\n

Keep ductwork short and well supported, with adequate sizes, limited resistance and appropriate fire and acoustic detailing.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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04<\/p>\n\n\n\n

Insulate and seal the ducts<\/h3>\n\n\n\n

Control leakage and heat loss, especially on intake and exhaust runs in cold spaces; follow the product design requirements.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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05<\/p>\n\n\n\n

Detail condensate and frost control<\/h3>\n\n\n\n

Provide a correctly trapped\/drained condensate route as required and protect operation in cold weather.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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06<\/p>\n\n\n\n

Choose practical controls<\/h3>\n\n\n\n

Allow sensible boost, bypass and filter alerts, with clear instructions the household can use.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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07<\/p>\n\n\n\n

Commission & balance<\/h3>\n\n\n\n

Measure supply and extract rates at terminals, balance the whole system and hand over records and settings.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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08<\/p>\n\n\n\n

Maintain access and filters<\/h3>\n\n\n\n

Keep the unit, filters, ducts, terminals and drain accessible; inspect and clean at the intervals specified by the manufacturer.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

A system needs verified flow rates at its terminals, an appropriate overall supply\/extract balance, a documented handover and straightforward maintenance instructions.<\/p>\n<\/div>\n\n\n\n

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BUILDING REGULATIONS & GUIDANCE<\/p>\n\n\n\n

Use the guidance applicable to the work.<\/h2>\n<\/div>\n\n\n\n
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Check the relevant UK nation<\/h3>\n\n\n\n

Requirements vary between England, Wales, Scotland and Northern Ireland, and may depend on the date and scope of building work.<\/p>\n<\/div>\n\n\n\n

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England \u2014 Approved Document F<\/h3>\n\n\n\n

The 2026 edition and earlier editions apply to different regulatory circumstances. Follow the applicable requirements for design, testing, commissioning and homeowner information.<\/p>\n<\/div>\n\n\n\n

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Read the official guidance<\/h3>\n\n\n\n

Approved Document F \u2014 versions and guidance \u2192<\/a><\/p>\n<\/div>\n\n\n\n

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Read the 2026 edition<\/h3>\n\n\n\n

Approved Document F (2026) \u2192<\/a><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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IS MVHR SUITABLE FOR YOUR HOME?<\/p>\n\n\n\n

Start with the building and the available duct space.<\/h2>\n<\/div>\n\n\n\n
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MVHR is commonly considered for homes with good airtightness and a planned whole-house ventilation route, including new builds and comprehensive retrofits.<\/p>\n\n\n\n

In an existing home, achieving continuous supply and extract routes may involve opening ceilings and boxing in ducts. Existing background vents, loft conditions, filter access, intake positions, condensate drainage and the effect on combustion appliances all need to be assessed.<\/p>\n\n\n\n

A mould or condensation problem alone does not mean MVHR is the solution. Identify the underlying moisture and building issues before specifying equipment.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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2<\/p>\n\n\n\n

separate air streams \u2014 linked by one heat exchanger.<\/p>\n<\/div>\n\n\n\n

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MY WARM HOME VIEW<\/p>\n\n\n\n

Good heat recovery starts with good ventilation design.<\/h2>\n\n\n\n

MVHR can help maintain indoor air quality while reducing ventilation heat loss, but only when the home, duct network, airtightness and installation details work together.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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BEFORE YOU INSTALL MVHR<\/p>\n\n\n\n

Design the air path first. Choose the unit second.<\/h2>\n<\/div>\n\n\n\n
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A balanced, commissioned and maintainable system is the goal \u2014 not simply a published heat-recovery percentage.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

01 Understand Balanced mechanical supply and extract. 02 Follow the air Separate air streams meet at the heat exchanger. 03 Recover the heat Benefits, efficiency and limitations. 04 Design & check Airtightness, ducts, controls and commissioning. THE SHORT VERSION Ventilation with less heat lost. Mechanical ventilation with heat recovery (MVHR) continuously extracts stale, moist air […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"pagelayer_contact_templates":[],"_pagelayer_content":"","footnotes":""},"class_list":["post-4878","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/mywarmhome.co.uk\/stage\/wp-json\/wp\/v2\/pages\/4878","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mywarmhome.co.uk\/stage\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/mywarmhome.co.uk\/stage\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/mywarmhome.co.uk\/stage\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mywarmhome.co.uk\/stage\/wp-json\/wp\/v2\/comments?post=4878"}],"version-history":[{"count":3,"href":"https:\/\/mywarmhome.co.uk\/stage\/wp-json\/wp\/v2\/pages\/4878\/revisions"}],"predecessor-version":[{"id":4885,"href":"https:\/\/mywarmhome.co.uk\/stage\/wp-json\/wp\/v2\/pages\/4878\/revisions\/4885"}],"wp:attachment":[{"href":"https:\/\/mywarmhome.co.uk\/stage\/wp-json\/wp\/v2\/media?parent=4878"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}