Glossary
MVHR glossary
The jargon, explained simply.
- Airtightness
- How little air leaks through the building fabric. Airtight homes need deliberate mechanical ventilation.
- Approved Document F (Part F)
- The part of the Building Regulations for England that sets requirements for ventilation in buildings.
- Boost mode
- A temporary higher fan speed, used during cooking, showering or when extra ventilation is needed.
- Commissioning
- Measuring and adjusting a ventilation system so it delivers its design airflow rates, and recording the results.
- Condensate
- Water produced when warm humid air cools inside the heat exchanger. It drains from the unit via a trap and pipe.
- Extract air
- Stale, humid air removed from kitchens, bathrooms and utility rooms.
- F7 filter
- A finer filter grade that captures pollen and fine particulates, commonly used on the supply side.
- Flow hood
- A calibrated instrument used to measure airflow at a valve or grille.
- G4 filter
- A coarse filter grade used to protect an MVHR unit from dust and fibres, commonly on the extract side.
- Heat exchanger (core)
- The part of an MVHR unit where heat passes from outgoing air to incoming air without the two airstreams mixing.
- MEV
- Mechanical Extract Ventilation: a fan system that continuously extracts air from wet rooms, with fresh air entering through vents.
- MVHR
- Mechanical Ventilation with Heat Recovery: a whole-home ventilation system that extracts stale air, supplies fresh filtered air and transfers heat between the two airstreams.
- PIV
- Positive Input Ventilation: a fan system, usually in the loft, that pushes filtered air into the home.
- Summer bypass
- A damper that lets air bypass the heat exchanger when heat recovery isn't wanted, such as on warm days or at night in summer.
- Supply air
- Fresh, filtered air delivered to living rooms and bedrooms by an MVHR system.
- Trickle ventilation
- The continuous low-rate background operation of a ventilation system, as opposed to boost.
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