Vento Duo - For Toilets & Bathrooms MVHR Single Room Heat Recovery Unit

Yes, VENTO DUO is a true push-pull (alternate-flow) ventilation fan: its twin-fan design delivers balanced ventilation by supplying fresh, filtered air and extracting humid, stale air, while recovering up to 85 % of outgoing heat.

As a decentralised, single-room heat recovery ventilation unit (a duct-free MVHR alternative), it provides energy-efficient, demand-controlled operation to improve indoor air quality, control humidity, and prevent mould in bathrooms and wet rooms.

Unlike traditional extractor fans (which only pull air out) or supply-only units, push-pull systems use two fans in one wall-mounted unit to maintain balanced airflow and recover heat, offering a compact MVHR alternative without any ductwork.

An alternate flow heat recovery fan, sometimes called a push-pull ventilation or twin-fan MVHR alternative, is a compact, wall-mounted unit that handles both supply and extraction in one device.

Inside, two fans work in alternating cycles: one pulls out warm, humid air, while the other pushes in fresh, filtered air through a shared ceramic heat exchanger.

This swapping action recovers up to 85–95% of the heat that would otherwise be lost.

By balancing airflow room by room, it prevents pressure imbalances and reduces condensation spikes that lead to black mould. As a decentralised, ductless solution, it’s ideal for bathrooms, kitchens, bedrooms, or any single room and multiple units can link wirelessly to create a whole-house heat recovery system without costly ductwork.

Yes, VENTO DUO is a true alternate-flow heat recovery fan. Its balanced, push-pull design pulls out warm, humid air and pushes in fresh, filtered air through a shared ceramic core, recovering up to 85 % of heat.

As a decentralised, duct-free single-room heat recovery unit (an MVHR alternative), it delivers balanced ventilation, cuts condensation spikes, and prevents mould, perfect for bathrooms, toilets, and wet rooms.

Push-Pull Ventilation (Alternate-Flow Fans)

Push-pull ventilation units like VENTO DUO are decentralised, wall-mounted fans that alternate between extracting stale air and supplying fresh air through a shared heat exchanger. They fit directly into an exterior wall with no ductwork, making them ideal as a single-room heat recovery solution. You can install one in a bathroom or wet room and later add more units, linking them wirelessly to cover the whole home.

Traditional MVHR Systems

MVHR (Mechanical Ventilation with Heat Recovery) is a centralised, duct-based system. A single, larger unit sits in a plant room or loft and uses ducts to extract and supply air simultaneously to every room. It delivers truly continuous, balanced ventilation but requires extensive planning, installation cost, and ongoing duct maintenance.

Choosing Between Them

If you need a quick, ductless MVHR alternative that can be scaled room by room, push-pull ventilation is more flexible and cost-effective. For a whole-house installation from the start, with continuous simultaneous airflow and higher upfront investment, traditional MVHR remains the go-to choice.

By recovering up to 85 % of the heat that would otherwise be lost through a standard extractor fan, VENTO DUO can cut ventilation-related heat loss by roughly the same amount, turning each £1 of wasted energy into about 85p of retained warmth.

When you install multiple VENTO DUO units in different rooms, such as bathrooms, en-suites and utility areas—you can achieve up to 20% reduction in overall home heating demand, since each single-room fan pre-heats incoming air and minimises heat loss across the property.

Push-pull ventilation units are designed for quiet, unobtrusive operation. Thanks to their alternate-flow balanced fan design and acoustic baffle vents, noise levels typically run between 24 – 38 dB(A), about the volume of a soft whisper or rustling leaves.

For example, the VENTO DUO can operate as low as 24 dB(A) at 3 metres, making it virtually inaudible in most bathrooms, toilets, and wet rooms.

Because each cycle alternates smoothly between extract and supply, there’s no sudden rush of air or “whoosh” sound, and the ceramic heat exchanger further dampens mechanical noise.

In automatic mode, fans adjust speed to match humidity levels, keeping sound consistently low while maintaining optimal indoor air quality.

In short, modern push-pull units deliver energy-efficient, balanced ventilation without the distraction of traditional fan noise, ideal for spaces where peace and comfort matter.

Push-pull (alternate flow) ventilation prevents black mould by constantly cycling air through alternating extract and supply phases. In the “pull” phase, warm, humid air is drawn out before it can settle on cold surfaces and form condensation, a primary breeding ground for black mould spores. In the “push” phase, fresh, filtered air is reintroduced, lowering relative humidity and disrupting the moisture balance mould needs to thrive.

This alternate flow ventilation approach ensures a continuous dehumidification cycle that traditional extractor fans can’t match.

By integrating a ceramic heat exchanger, alternate flow fans pre-heat incoming air with warmth from the extracted stream, reducing surface temperature differences and further limiting condensation on walls, ceilings, and window reveals.

Many decentralised, single-room alternate flow heat recovery units feature built-in humidity sensors that automatically boost airflow during peak moisture events (like hot showers), ensuring balanced ventilation and energy-efficient operation.

The result is a ductless MVHR alternative that maintains healthy indoor air quality, effectively controls moisture, and keeps bathrooms, toilets, and wet rooms mould-free.

Alternate-flow single-room heat recovery units vs. dMEV systems

Balanced ventilation & heat recovery

Alternate-flow (push-pull) units deliver balanced airflow by both extracting stale air and supplying fresh air through a shared heat exchanger, recovering up to 85–95 % of outgoing heat. In contrast, dMEV (demand-controlled mechanical extract ventilation) only pulls air out when humidity or pollutants rise, then relies on cold air infiltration to replace it, losing all the heat in the exhaust. If you’re looking for a duct-free MVHR alternative that cuts energy waste, an alternate-flow single-room heat recovery fan offers clear advantages.

Energy efficiency & running costs

Because alternate-flow units pre-heat incoming air, they can reduce heating demand by up to 20 % per treated room, making them a more energy-efficient solution than extract-only dMEV fans. dMEV can lower humidity peaks and save fan power versus continuous extract, but it won’t recapture any warmth so your heating system must work harder to warm incoming cold air.

Installation & flexibility

Both systems are decentralised, wall-mounted, and ideal for retrofits: no ductwork, no loft-mounted plant. dMEV units tend to be smaller, simpler, and cheaper to install, perfect if budget is paramount and heat recovery isn’t essential. Alternate-flow fans cost more upfront but give single-room heat recovery benefits and can be linked wirelessly to form a whole-house heat recovery ventilation system over time.

Indoor air quality & comfort

dMEV responds to spikes in humidity, protecting against condensation and mould but it can create pressure imbalances and draughts when fresh air infil­trates randomly. Alternate-flow units maintain constant pressure, continuously renewing air without drafts, and control mould more proactively via heat recovery and continuous dehumidification.

Which to choose?

Use dMEV if you need a low-cost, demand-controlled extract fan for moisture-prone spaces and heat recovery isn’t a priority. Opt for an alternate-flow single-room heat recovery unit (e.g. VENTO DUO) when you want a duct-free MVHR alternative, superior energy savings, and balanced, whole-room ventilation in bathrooms, toilets, or wet rooms.

Alternate-flow heat recovery fans are remarkably low-maintenance, but a few simple tasks will keep your decentralised ventilation system running at peak efficiency.

Every 6–12 months, lightly vacuum the fan blades and housing to clear dust buildup that can impede airflow or increase noise, and quarterly check your external acoustic baffle vents for debris or blockages. Finally, schedule a professional service every 2–3 years to verify motor health, airtight seals, and control electronics. By following these steps, your alternate-flow heat recovery fan, an energy-efficient, duct-free MVHR alternative, will continue delivering healthy, mould-free air with minimal effort.