{"title":"Positive Input Ventilation (PIV)","description":"\u003cp\u003ePositive Input Ventilation (PIV) units are one of the most effective and cost-efficient ways to eliminate condensation, damp, and black mould in UK homes. Rather than extracting air like a standard extractor fan, a PIV system works in reverse — drawing fresh, filtered air from the loft space and continuously distributing it throughout the home. The gentle positive pressure this creates forces stale, humid air out through natural gaps and leakage points in the building fabric, keeping indoor humidity low and preventing the conditions that cause condensation and mould to form.\u003c\/p\u003e\n\u003cp\u003ePIV units are suitable for most UK house types with a loft space. They connect to a single ceiling diffuser — typically in a hallway — so there's no complex ductwork run to every room. Installation is straightforward and most units can be fitted in a day. Running costs are low: most PIV units consume 15–30 watts continuously, which works out to roughly £20–£50 per year at typical UK electricity rates. For colder climates or less well-insulated homes, heated PIV units — such as the Vent-Axia PoziDry Pro with Heater or the Elta PIV ONE PLUS+ — warm the incoming air before it enters the home, making the system effective and comfortable year-round.\u003c\/p\u003e\n\u003cp\u003eOur PIV range includes 7 loft-mounted units from Vent-Axia and Elta, ranging from the compact PoziDry Compact Pro (suitable for smaller properties) to the PoziDry Pro Multi Storey for larger homes. If you're not sure which model is right for your property, read our \u003ca href=\"\/blogs\/help-advice\/what-is-positive-input-ventilation\"\u003ePIV guide\u003c\/a\u003e or see our \u003ca href=\"\/blogs\/help-advice\/vent-axia-vs-elta-which-piv-unit-to-choose\"\u003eVent-Axia vs Elta comparison\u003c\/a\u003e to help narrow it down.\u003c\/p\u003e\n\u003ch3 class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eWhat is a positive input ventilation (PIV) unit?\u003c\/h3\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eA PIV unit is a whole-house ventilation system that sits in the loft and continuously supplies filtered fresh air into the home via a ceiling diffuser, usually in the hallway. The gentle positive pressure pushes stale, humid air out through gaps and vents in the building fabric — reducing condensation, mould, and indoor pollutants without requiring a full MVHR installation.\u003c\/p\u003e\n\u003ch3 class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eDo I need a PIV unit with a heater?\u003c\/h3\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eIn most UK homes, yes — a heater is recommended. Loft temperatures can drop significantly in winter, and without a heater the system would introduce cold air into the living space. Units with integral heaters gently warm the supply air to a comfortable temperature before distributing it, making them far more effective year-round. Our best-selling models include the Vent-Axia PoziDry Pro with Heater and the Elta PIV ONE PLUS+.\u003c\/p\u003e\n\u003ch3 class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eIs a PIV system easy to install?\u003c\/h3\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003ePIV units are among the simpler whole-house ventilation systems to install — they don't require ductwork runs to every room. The unit is mounted in the loft, connected to a single ceiling diffuser in the hallway below, and wired to a standard fused spur. Most installations are completed in a day.\u003c\/p\u003e\n\u003ch3 class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eWhat size property does a PIV unit suit?\u003c\/h3\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003ePIV systems are designed for standard residential properties — typically houses with a loft space. They are not generally suitable for flats or properties without a loft. For properties without a loft, consider a continuous mechanical extract (MEV) or MVHR system instead.\u003c\/p\u003e\n\u003ch3 class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eHow much does it cost to run a PIV unit?\u003c\/h3\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003ePIV units are designed to be low-energy, typically consuming 15–30 watts in standard operation — comparable to a low-energy light bulb. Annual running costs are generally in the range of £20–£50 depending on usage and heating requirements.\u003c\/p\u003e","products":[{"product_id":"vent-axia-lo-carbon-pozidry-compact-pro-piv-with-integral-heater-479188","title":"Vent-Axia Lo Carbon PoziDry Compact Pro PIV with Integral Heater 479188","description":"\u003cp\u003eThe Vent-Axia PoziDry Compact Pro (479188) is the smallest PIV unit on the market, with an integral heater — so you can always find space for it, even in the smallest apartment. With 2 inlet and 2 outlet positions it can be installed in 16 orientations, and the flexible heater can sit at the unit or diffuser to save up to 4 °C of heat loss.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eUltra-small unit; comes with mounting bracket and lightweight backplate\u003c\/li\u003e\n\u003cli\u003eRemovable inner cartridge for easy repairs and maintenance\u003c\/li\u003e\n\u003cli\u003eFlow adjustable in 1 l\/s increments, up to 30 l\/s\u003c\/li\u003e\n\u003cli\u003eExtremely low running costs, from less than 9p per week\u003c\/li\u003e\n\u003cli\u003eWashable G4 filter as standard; higher-grade F7 filter available\u003c\/li\u003e\n\u003cli\u003eAdvanced data logger and 3-digit settings lock\u003c\/li\u003e\n\u003cli\u003eIdeal for flats with mould in a habitable room\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eSuitable for\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eApartments and flats without loft space\u003c\/li\u003e\n\u003cli\u003eSolving mould and condensation in residential properties\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation\u003c\/h3\u003e\n\u003cp\u003eWall-mounted over 1.8 m from the floor, in any of 16 orientations. Total rigid duct (inlet and outlet) should not exceed 2.5 m, with a maximum of two 90° bends. Should be installed by a competent person.\u003c\/p\u003e","brand":"Vent-Axia","offers":[{"title":"Default Title","offer_id":33826300985477,"sku":"479188","price":368.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0355\/3932\/0965\/products\/vent-axia-lo-carbon_pozidry_compact_pro.jpg?v=1728411328"},{"product_id":"vent-axia-pozidry-pro-positive-input-ventilation-with-heater-476311","title":"Vent-Axia Pozidry Pro Positive Input Ventilation with Heater 476311","description":"\u003cp\u003eThe Vent-Axia PoziDry Pro with Heater (476311) is a loft-mounted Positive Input Ventilation (PIV) unit designed to eradicate condensation and mould from the home, with an integral heater that gently tempers the incoming air for comfort. It improves indoor air quality by reducing humidity and eradicating the conditions that lead to mould and related health issues.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eHighly effective at reducing condensation and mould\u003c\/li\u003e\n\u003cli\u003eEfficient integral heater, mountable at the unit or diffuser (up to 4 °C warmer at the room)\u003c\/li\u003e\n\u003cli\u003eAnti-vibration joist mounting legs as standard\u003c\/li\u003e\n\u003cli\u003eSelectable air capacities to suit floor areas up to 150 m²\u003c\/li\u003e\n\u003cli\u003eSmart Sense technology for simple control and data logging\u003c\/li\u003e\n\u003cli\u003eLo-Carbon motor technology for low running costs; ultra-low sound from 9 dB(A)\u003c\/li\u003e\n\u003cli\u003eF7 filter option down to PM2.5; up to 5-year maintenance-free G4 filter\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eSuitable for\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eProperties with a loft, up to 150 m²\u003c\/li\u003e\n\u003cli\u003eHomes suffering from condensation and mould\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation\u003c\/h3\u003e\n\u003cp\u003eLoft installation, hung from the rafters or mounted on the adjustable anti-vibration feet, supplying air through a ceiling diffuser. Should be installed by a competent person.\u003c\/p\u003e","brand":"Vent-Axia","offers":[{"title":"Default Title","offer_id":33826858369157,"sku":"476311","price":381.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0355\/3932\/0965\/files\/vent_axia_pozidry_with_heater.jpg?v=1706290760"},{"product_id":"vent-axia-pozidry-pro-positive-input-ventilation-476310","title":"Vent-Axia Pozidry Pro Positive Input Ventilation 476310","description":"\u003cp\u003eThe Vent-Axia PoziDry Pro (476310) is a loft-mounted Positive Input Ventilation (PIV) unit designed to eradicate condensation and mould from the home. It improves indoor air quality by reducing humidity and quickly eradicating the conditions that lead to mould growth and related health issues such as asthma and itchy skin. This model does not include a heater.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eHighly effective at reducing condensation and mould\u003c\/li\u003e\n\u003cli\u003eAnti-vibration joist mounting legs as standard\u003c\/li\u003e\n\u003cli\u003eSelectable air capacities to suit floor areas up to 150 m²\u003c\/li\u003e\n\u003cli\u003eSmart Sense technology for simple control and data logging\u003c\/li\u003e\n\u003cli\u003eLo-Carbon motor technology for low running costs\u003c\/li\u003e\n\u003cli\u003eUltra-low sound level, as low as 9 dB(A)\u003c\/li\u003e\n\u003cli\u003eF7 filter option down to PM2.5 (including diesel particulates)\u003c\/li\u003e\n\u003cli\u003eUp to 5-year maintenance-free G4 filter; IPX2 rated\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eSuitable for\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSingle-floor homes and apartments up to 150 m²\u003c\/li\u003e\n\u003cli\u003eHomes suffering from condensation and mould\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation\u003c\/h3\u003e\n\u003cp\u003eLoft installation, hung from the rafters or mounted on the adjustable anti-vibration feet, supplying air through a ceiling diffuser. Supplied with flexible ducting, jubilee clips and ceiling grille. Should be installed by a competent person.\u003c\/p\u003e","brand":"Vent-Axia","offers":[{"title":"Default Title","offer_id":37830676611228,"sku":"476310","price":289.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0355\/3932\/0965\/files\/vent_axia_pozidry_without_heater.jpg?v=1706291123"},{"product_id":"vent-axia-pozidry-pro-positive-input-ventilation-with-heater-multi-storey-476312","title":"Vent-Axia Pozidry Pro Positive Input Ventilation with Heater Multi Storey 476312","description":"\u003cp\u003eThe Vent-Axia PoziDry Pro Multi Storey (476312) is a loft-mounted Positive Input Ventilation (PIV) unit with a built-in 500 W heater and a fire damper, for whole-house mould and condensation control. Smart Sense control allows quick, accurate setup, and variable speed control makes it effective in properties up to 200 m². An automatic summer shut-off stops warm air returning into the home.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eBuilt-in 500 W heater and fire damper for added protection\u003c\/li\u003e\n\u003cli\u003eFire damper can be wired to a fire alarm; intumescent ducting and fire-stopping diffuser rated up to 1 hour\u003c\/li\u003e\n\u003cli\u003eFully adjustable between 11 and 60 l\/s\u003c\/li\u003e\n\u003cli\u003eAnti-vibration joist mounting legs as standard\u003c\/li\u003e\n\u003cli\u003eSmart Sense technology and Lo-Carbon motor for low running costs\u003c\/li\u003e\n\u003cli\u003eG4 filter with F7 (PM2.5) upgrade option\u003c\/li\u003e\n\u003cli\u003eRadon mode for continuous ventilation where radon levels are high\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eSuitable for\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eMulti-storey properties up to 200 m²\u003c\/li\u003e\n\u003cli\u003eWhole-house condensation and mould control\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation\u003c\/h3\u003e\n\u003cp\u003eLoft installation on anti-vibration feet, supplying air through the fire-stopping ceiling diffuser. Should be installed by a competent person.\u003c\/p\u003e","brand":"Vent-Axia","offers":[{"title":"Default Title","offer_id":47706902724929,"sku":"476312","price":538.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0355\/3932\/0965\/files\/vent_axia_pozidry_with_heater_482c5e4c-9e2c-494f-9504-b9e05f28c7c0.jpg?v=1706558178"},{"product_id":"elta-piv-one-loft-mounted-positive-input-ventilation-unit","title":"Elta PIV ONE Loft Mounted Positive Input Ventilation Unit","description":"\u003cp\u003eThe Elta PIV ONE is a loft-mounted, whole-house Positive Input Ventilation unit designed to introduce fresh, clean, filtered air into the home. It dilutes, displaces and replaces stale, contaminated, humid air, creating a healthier indoor environment — curing condensation and mould and reducing radon gas concentration. This model does not include a heater.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eCures condensation and mould and improves indoor air quality\u003c\/li\u003e\n\u003cli\u003eTwo filters remove dust, pollen and external air pollutants\u003c\/li\u003e\n\u003cli\u003eQuiet, energy-saving EC motor\u003c\/li\u003e\n\u003cli\u003eAutomatic humidity boost clears excess moisture\u003c\/li\u003e\n\u003cli\u003eSuitable for floor or ceiling installation, in any position\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eSuitable for\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eWhole-house ventilation\u003c\/li\u003e\n\u003cli\u003eHomes suffering from condensation and mould\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation\u003c\/h3\u003e\n\u003cp\u003eLoft installation, suitable for floor or ceiling mounting in any position. Should be installed by a competent person.\u003c\/p\u003e","brand":"Elta","offers":[{"title":"Default Title","offer_id":48939511382337,"sku":"PIVONE","price":380.59,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0355\/3932\/0965\/files\/01_9fe241f2-bbe6-490d-9095-d5f939bd8ab9.jpg?v=1718829261"},{"product_id":"elta-piv-one-plus-loft-mounted-positive-input-ventilation-unit-with-heater-advanced-control","title":"Elta PIV ONE PLUS+ Loft Mounted Positive Input Ventilation Unit with Heater \u0026 Advanced Control","description":"\u003cp\u003eThe Elta PIV ONE Plus+ is a whole-house Positive Input Ventilation unit with a built-in heater and advanced control, designed to introduce fresh, clean, filtered air into the home. It dilutes, displaces and replaces stale, humid air — curing condensation and mould, diluting harmful pathogens and reducing radon gas concentration — while tempering the incoming air for comfort.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eCures condensation and mould and improves indoor air quality\u003c\/li\u003e\n\u003cli\u003eBuilt-in heater tempers the incoming air for comfort\u003c\/li\u003e\n\u003cli\u003eAdvanced control with automatic humidity boost\u003c\/li\u003e\n\u003cli\u003eTwo filters remove dust, pollen and external air pollutants\u003c\/li\u003e\n\u003cli\u003eQuiet, energy-saving operation; easy to install and cost-effective\u003c\/li\u003e\n\u003cli\u003eSuitable for floor or ceiling installation, in any position\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eSuitable for\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eWhole-house ventilation\u003c\/li\u003e\n\u003cli\u003eHomes suffering from condensation and mould\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation\u003c\/h3\u003e\n\u003cp\u003eSuitable for floor or ceiling installation in any position. Should be installed by a competent person.\u003c\/p\u003e","brand":"Elta","offers":[{"title":"Default Title","offer_id":48939593302337,"sku":"PIVONEPlus+","price":475.19,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0355\/3932\/0965\/files\/01_9fe241f2-bbe6-490d-9095-d5f939bd8ab9.jpg?v=1718829261"},{"product_id":"elta-sano-ipiv-loft-h-loft-mounted-positive-input-ventilation-unit-with-heater","title":"Elta SANO IPIV LOFT H Loft Mounted Positive Input Ventilation Unit with Heater","description":"\u003cp\u003eThe Elta SANO Intelligent PIV Loft H is a loft-mounted, whole-house Positive Input Ventilation unit with a built-in heater. Ultra-quiet, low-energy and low-maintenance, it uses the well-established PIV principle to cure condensation and mould and reduce radon concentration, tempering the incoming air for comfort.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eCures condensation and mould and improves indoor air quality\u003c\/li\u003e\n\u003cli\u003eBuilt-in heater tempers the incoming air for comfort\u003c\/li\u003e\n\u003cli\u003eIntegral temperature and humidity sensors automatically regulate airflow\u003c\/li\u003e\n\u003cli\u003eTwo filters remove dust, pollen and external air pollutants\u003c\/li\u003e\n\u003cli\u003eUltra-quiet, low-energy operation\u003c\/li\u003e\n\u003cli\u003eSuitable for floor or ceiling installation, in any position\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eSuitable for\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eWhole-house ventilation\u003c\/li\u003e\n\u003cli\u003eHomes suffering from condensation and mould\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInstallation\u003c\/h3\u003e\n\u003cp\u003eLoft installation, suitable for floor or ceiling mounting in any position. Should be installed by a competent person.\u003c\/p\u003e","brand":"Elta","offers":[{"title":"Default Title","offer_id":48939683742017,"sku":"SANOIPIVLOFTH","price":439.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0355\/3932\/0965\/files\/01_f39c8c44-4365-41b6-ae3e-51af8b2ff23c.jpg?v=1718830601"}],"url":"https:\/\/www.efans.co.uk\/collections\/positive-input-ventilation-piv\/brand_elta.oembed","provider":"eFans Direct Ltd","version":"1.0","type":"link"}