Before we begin, here's a quick link to our dMVHR offering.
Ever noticed how stuffy your home gets when the windows stay shut for too long? Or how moisture clings to bedroom windows when you wake up in the morning? Good ventilation is a must, but cracking open a window isn’t always energy-efficient (or cozy).
That’s where mechanical ventilation comes in. But with all the acronyms flying around - MVHR, dMVHR, dMEV - it can feel like you need an engineering degree just to figure out what’s best for your home.
Don’t worry - we've got you covered! In this article, we'll break down dMVHR in plain English, show you where it works best, and help you decide if it’s the right fit for your home. Let’s dive in!
First off—What is dMVHR?
Alright, let’s start with the basics. Ventilation is all about removing stale, humid air from your home and replacing it with fresh air. The simplest way? Open a window. But that also lets out a ton of heat, which means higher heating bills (not ideal).
Mechanical ventilation systems help solve this by managing airflow in a controlled way. You’ve probably seen (or have) extractor fans in your kitchen or bathroom — These are usually basic ventilation systems that pull out steam and odours.
But here’s the kicker: even those standard extractor fans still suck warm air out of your home which means cold air will be pulled into the home in winter months to replace the out-going air (especially through open windows). This requires your heating system to work overtime to keep things comfortable.
That’s where heat recovery comes in. Instead of just dumping all that warm air outside, dMVHR (decentralized Mechanical Ventilation with Heat Recovery) takes the outgoing heat, captures it, and uses it to warm fresh air from outside, which the unit also supplies.
Think of it like recycling — but for warmth!
dMVHR vs. MVHR: What’s the Difference?
Both MVHR and dMVHR do the same thing - ventilate your home while recovering heat — but MVHR is a whole-house system that uses a central unit with ducting to multiple rooms. Fantastic for new builds or full-scale renovations, but let’s be real: retrofitting one into an existing home is a major headache.
That’s where dMVHR comes in! Instead of running ducts everywhere, dMVHR units work on a room-by-room basis—kind of like mini MVHR systems. They’re installed in exterior walls (similar to extractor fans) and are much easier to add to an existing home without tearing up ceilings and walls.
How Does dMVHR Work?
Different models use different tricks, but they all work on the same basic principle:
They pull stale, warm air out of the room.
A heat exchanger inside the unit grabs that warmth before the air exits.
Fresh air from outside is pulled in, warmed by the captured heat, and circulated into the room.
Some brands, like Envirovent and Vent Axia, do this process continuously in both directions at once. Others, like Blauberg’s Vento range, use a push-pull method — first venting out air, then reversing to bring fresh air back in through the heated exchanger. This can be a fantastic option if you are installing more than one of the Vento units, as they can be wirelessly connected to work in tandem. As one unit, say in a living room, is extracting air out of the building, another, in say an upstairs landing, is supplying fresh air into the building and then vice versa as they switch together between supply and extraction, keeping a balanced internal air pressure.
For most rooms, both methods work well, but for bathrooms, push-pull models (both installed on their own or linked to other units elsewhere in the house, such as the Vento units) can be a problem. When the unit is in "supply" mode, steam from your shower isn’t being removed, and it can drift into other parts of the house! That’s why Blauberg designed the Vento-Duo, which continuously extracts while still recovering heat, especially for bathroom applications.
Where Should You Install dMVHR?
Not sure where a dMVHR unit would work best? Here are some ideal spots:
🏠 Utility Rooms
Washing machines and dryers create a lot of heat and moisture. A dMVHR unit helps manage humidity while recycling that extra warmth back into your home.
🍳 Kitchens
Cooking generates heat, steam, and odours — perfect for a dMVHR system. Bonus: the Envirovent HeatSava model can be mounted horizontally above kitchen cabinets, so it’s tucked away out of sight.
🔥 Living Rooms with Fireplaces or Wood Burners
Love the cozy glow of a fire? dMVHR helps extract smoke and dangerous fumes while keeping the room warm. Win-win!
🌞 Conservatories
These rooms get humid, especially in winter when warm indoor air meets cold glass. A dMVHR unit keeps moisture down while letting you hold onto that lovely solar heat.
🛏️ Bedrooms
Did you know we release moisture through breathing and sweating whilst sleeping? dMVHR helps keep bedrooms fresh and comfortable by clearing out stale, humid air and replacing it with oxygen-rich air, all without letting the room get cold overnight.
📌 Pro Tip: If you’re a light sleeper, look for models where you can disable the "boost" function at night to avoid unexpected fan noise.
🚿 Bathrooms & Wet Rooms
Okay, so here’s where dMVHR isn’t always the best option. Because heat recovery systems generally move air more slowly to maximize heat transfer, they might not clear out steam fast enough. If your bathroom has a history of damp or mold, a high-powered continuous extractor fan (like a dMEV unit) might be the better bet. However, the constant running nature of dMVHR units can still be excellent choices for less problematic bathrooms - just remember to make sure the model you are choosing supplies and extracts at the same time, not push/pull!
dMVHR: Is It Right for You?
If you can’t install a full MVHR system, dMVHR is a fantastic alternative. It’s energy-efficient, keeps air fresh, and helps you hold onto the warmth you’ve already paid for. Fantastic in older homes which have been re-insulated and brilliant in more modern builds that already struggle with air movement and natural supply of fresh air due to their more air-tight construction!
That said, it’s not the best choice for every room, especially bathrooms with serious moisture issues. For those spaces, you’re better off with a high-extraction constant running fan.
Final Thoughts? dMVHR is a brilliant way to improve ventilation without jacking up your heating bill. If you’re serious about making your home more energy-efficient, it’s worth considering!
Want to see one in action? Check out CharlieDIYte’s YouTube video on dMVHR — he breaks down the install process and gives some solid real-world insights.