MVHR (mechanical ventilation with heat recovery)
This is a whole-house system that extracts air from wet rooms and supplies fresh air to living areas and bedrooms, recovering heat in the process.
- A single central unit, usually in a loft, cupboard or utility room
- Four ducts connected to the unit
- Round ceiling or wall valves in most rooms, including bedrooms and living areas
- The system runs continuously, often with a boost setting
MEV (mechanical extract ventilation)
This system uses a central fan to extract air from wet rooms only. Fresh air enters through trickle vents in the windows.
- A single central unit, often smaller than an MVHR unit, in a cupboard or ceiling void
- Two ducts connected to the unit: one collecting air from the rooms and one discharging it outside
- Valves or grilles in kitchens, bathrooms and utility rooms, but not in bedrooms or living areas
dMVHR (single-room heat recovery)
These are individual units fitted through an external wall, each ventilating a single room with heat recovery.
- A unit on the wall of the room, often in a kitchen or bathroom, sometimes with a pull cord or controls
- No central unit or ducting
- The unit runs continuously at low speed, and speeds up when humidity rises or when it is boosted
PIV (positive input ventilation)
This is a unit, usually in the loft, that supplies filtered air to the home through a single ceiling diffuser.
- A single diffuser, commonly on the ceiling of the landing or hallway
- A unit in the loft directly above the diffuser
PIV servicing, repair and installation
Extractor fans
These are standard fans in bathrooms, en suites and kitchens. They run when the light is switched on, on a timer, or when humidity rises.
- A fan in the ceiling or wall of the room, extracting directly or through a short duct
- No heat recovery and no supply of fresh air
Extractor fan servicing and replacement
Further help
When requesting a quote, you can upload photographs of the unit and its label, and we will identify the system for you. Alternatively, please call us on 0208 1757 567.