Closest fitNuaire
MRXBOXAB-ECO5
Near its comfortable limitComfortable up to 181 m²About £1,610
Summer bypassHumidity sensing
MVHR design for self-builds
Your MVHR, designed room by room.
Log in, upload your plans, and within 48 hours your full compliant design is back in your account: how much air every room needs, where each valve and duct goes, which unit suits your house, and an acoustic report on the noise in every room. It's yours to build and commission however you like.
Back within 48 hoursTo Approved Document F 2021Passivhaus certified units on request36 units from 9 makers comparedNo tie-ins
Free size check
What size MVHR does your home need?
Tell us the size of your home and its rooms. We'll show the size of unit you need and a few that fit, allowing for the push-back of typical house ductwork. Your design then checks the unit against your actual ducts, room by room.
One unit will do it
About 59.4 litres of air a second when the kitchen and bathrooms are boosted, and 54 all day, by Approved Document F 2021. Expect one or two silencers: every one of our last 80 designs needed at least one, and 1 in 5 needed two. Your acoustic report says exactly where.
Best valueVent-Axia
Sentinel Kinetic Plus
Plenty of headroomComfortable up to 328 m²About £1,160
Summer bypassHumidity sensing
More headroomVent-Axia
Sentinel Econiq L
Plenty of headroomComfortable up to 295 m²
Summer bypassHumidity sensingApp control
See all 8 units big enough for your home
- MRXBOXAB-ECO5NuaireNear its comfortable limit
Comfortable up to 181 m²About £1,610 - MRXBOXAB-ECO4NuaireNear its comfortable limit
Comfortable up to 198 m²About £2,190 - Sentinel Econiq MVent-AxiaA good fit
Comfortable up to 217 m² - Adroit DV145AirflowA good fit
Comfortable up to 226 m²About £3,880 - HRV4.25 Q PlusTitonA good fit
Comfortable up to 231 m²About £1,650 - Sentinel Econiq LVent-AxiaPlenty of headroom
Comfortable up to 295 m² - Sentinel Kinetic PlusVent-AxiaPlenty of headroom
Comfortable up to 328 m²About £1,160 - Sentinel Kinetic High FlowVent-AxiaPlenty of headroom
Comfortable up to 333 m²About £1,330
A guide from your floor area and rooms, on the makers' own fan figures against typical house ductwork, against 100 Pa of ductwork on boost, the pressure makers rate their units at, with the controller at no more than 70% on boost and 40% every day (50% where the everyday rate sets the boost), unless you change them. Prices are typical online prices for the unit alone, September 2026.
Get your full designPrices
Three ways to do it
Design
£169
With a Passivhaus certified unit: £253.50
Your MVHR design, ready to build from.
- How much air every room needs, on normal and boost, to Approved Document F 2021
- A duct layout drawing (PDF): the unit, every valve with its airflow, and each duct's route and size
- The unit chosen for your house, with units from every major maker compared
Design and acoustic
£249
With a Passivhaus certified unit: £373.50
A quiet system, checked room by room, and everything to build it.
- Everything in Design
- An acoustic report: the noise in each room, with silencers placed where they're needed
- A cutting list: every piece of duct, its cut length and the fittings in order, run by run, each piece numbered to match the drawing
- A parts list with every part named and coded, ready to send to the major suppliers for an exact price
- An interactive 3D model, and an IFC file for your architect
- The unit's SAP figures for your energy assessor
- Unlimited installation questions, answered by your designer
Complete
£549
With a Passivhaus certified unit: £823.50
Everything in Design and acoustic, and we commission it.
- Everything in Design and acoustic
- An as-built drawing: our engineer marks any change made on site, and we redraw your system as fitted
- Commissioning by us: every valve set and measured with a calibrated powered flow hood, as Approved Document F requires from 24 March 2027, and the commissioning sheet filled in for building control
We commission nationwide. London, Birmingham, Manchester, Leeds, Liverpool, Sheffield, Bristol, Newcastle, Cardiff, Glasgow and Edinburgh are included; elsewhere we add travel at 45p a mile. Already have a design? Commissioning on its own is £350. Commissioning prices will rise from 24 March 2027, when the new powered flow hood rules start.
Choose CompleteBuilding to Passivhaus?
+50% on any design packageThe same design with a unit certified by the Passivhaus Institute.
- A unit certified by the Passivhaus Institute, chosen from its database of certified units
- Checked against the Institute's criteria: at least 75% heat recovery and no more than 0.45 Wh/m³ of fan power
- The unit's certified figures for your PHPP energy model
Not sure about your design?
£50We'll review it. A technical look at a design someone else made, purely on the ductwork, back within 48 hours.
What we cover
- Whether the design works in principle, checked from first principles
- Each room's airflow against Approved Document F
- Whether the unit chosen is the right size for the home
- Duct sizes and air speeds, run by run
- The layout: routes, fittings, branches and valve positions
- Insulation, where the ductwork needs it
- What's missing from the ductwork
- A written list of our suggestions
Not included: a duct resistance calculation, an acoustic report, a new design or drawings and a redesign.
Start a reviewPlans changed? Your first redesign is free. After that, each one is £39.
No tie-ins
The design is yours. Buy the parts from any supplier, have anyone fit it, and use your own commissioning engineer if you'd rather. It's up to you.
How it works
It all happens in your account
Plans in, design back in 48 hours, and your designer a message away the whole time. This is what you'll see.
Create your account
Your name, email and a password. Everything about your house stays in one place, on your phone or computer.
Upload your plans
Drop in your PDF drawings, or pick them from your phone. Forgotten one? Add it any time.
Pay securely
Card, Apple Pay or Google Pay, on Stripe's secure page. We never see your card details.
Ask your designer
Questions go straight to the designer working on your house. They reply on your order page, and we email you when they do.
See where it's up to
From paid to ready, with the time it's due: within 48 hours.
Download your design
The drawing, the acoustic report, the cutting list, the parts list and the 3D model, ready in your account.
Pictures from an example account. Then your installer fits it, and we commission it or your own engineer does from the design.
Sample design
See what you get
These are real outputs from one of our designs, a one-bedroom flat, marked SAMPLE.
SAMPLE
The drawing, every piece numbered
The duct layout as a PDF drawing: the unit, every valve with its airflow, each duct's size, and a number on every piece of duct. The same numbers run down the cutting list, so piece 31 on the drawing is piece 31 in the list.
Tap the drawing to open it full size. In your pack it's a PDF you can zoom and print.
SAMPLE
How much air each room needs
The rates each valve is set to: normal running all day, and boost when someone cooks or showers. Your commissioning engineer works from this table.
| Room | Air | Normal | Boost |
|---|---|---|---|
| Living | Fresh in | 11 l/s | 17 l/s |
| Bedroom 1 | Fresh in | 8 l/s | 12 l/s |
| Kitchen | Stale out | 8.5 l/s | 13 l/s |
| Bathroom | Stale out | 5.3 l/s | 8 l/s |
| Service cupboard | Stale out | 5.2 l/s | 8 l/s |
| Whole home | 19 l/s | 29 l/s |
SAMPLE
The noise in every room, before it's built
With the two silencers on the drawing fitted, every room on this flat comes out within Part F's 30 dB guidance, the loudest, Bedroom 1, at 18.7 dB. The report names each silencer, the run it goes on, and the level it gives every room.
SAMPLE
Cut it once, find it on the drawing
Each run from the unit: the straight pieces with their cut lengths, and every fitting in order with how far along the run it sits. Every piece carries the number printed on the PDF drawing, so the list and the drawing always match. Two of this flat's seven runs shown.
Supply run 1 from the MVHR
- 0.00 mMVHR unit connection, Ø125 spigot
- 30Piece 30: 220x90 ductcut 1.17 m
- 1.36 m90° bend, 220x90
- 31Piece 31: 220x90 ductcut 0.18 m
- 1.86 mSilencer
- 32Piece 32: 220x90 ductcut 0.64 m
- 2.67 mCrossing Extract run 2: step under it
- 33Piece 33: 220x90 duct, from 3 lengthscut 3.54 m
- 5.97 mCrossing Exhaust run 1: step under it
- 34Piece 34: 220x90 ductcut 0.65 m
- 6.69 mTee, 220x90, to Supply run 2
- 6.69 mReducer
- 6.69 mReducer
Supply run 2 from the tee on Supply run 1
- 35Piece 35: 204x60 ductcut 0.12 m
- 0.00 mValve plenum, Ø125 spigot
- 36Piece 36: 204x60 ductcut 1.47 m
- 2.16 mValve plenum, Ø125 spigot
Lengths come from the drawing. Measure on site before cutting.
SAMPLE
Every part, counted
The ductwork and fittings for this flat, with waste allowed on the duct. The whole list is here, 32 lines, with the valve and unit connections, flexible duct, clips and fixings.
| Part | Code | Qty |
|---|---|---|
| Rectangular duct 220x90 (flat channel) | VKC5728 | 27.1 m actual duct — order 30 m incl. waste |
| Rectangular duct 204x60 (flat channel) | VKC5628 | 10.5 m actual duct — order 12 m incl. waste |
| Flat 90 deg bend 204x60 | VKC5605 | 3 |
| Flat 90 deg bend 220x90 | VKC5705 | 6 |
| Flat tee 204x60 | VKC5630 | 2 |
| Flat tee 220x90 | VKC5730 | 1 |
| Duct connector / coupler 220x90 | VKC5708 | 12 |
| Duct connector / coupler 204x60 | VKC5608 | 1 |
| Reducer 220x90 → 204x60 | VKC5643 | 2 |
| Fire sleeve 220x90 — Quelfire QRS220/90SS (up to 60 min) | QRS220/90SS | 4 |
| Fire sleeve 204x60 — Quelfire QRS204/60SS (up to 90 min) | QRS204/60SS | 2 |
| In-line attenuator 220x90 (500 mm) | 9SL-500 | 1 |
| In-line attenuator 204x60 (500 mm) | 5SL-500 | 1 |
| Ceiling valve | VKC356F | 5 |
| Screws 4x40mm (grilles) | 20 | |
| Elbow bend 204x60 → Ø125 (valve connection) | VKC5645 | 5 |
| Flexible duct Ø125 (valve drops) | FLEX-125-ALU | 2.5 m |
| Jubilee clip Ø125 | CLIP-HOSE-125 | 5 |
| Duct insulation lagging roll (18 m x 1.2 m) | 2 | |
| Elbow bend 204x60 → Ø125 (MVHR connection) | VKC5645 | 1 |
| Elbow bend 220x90 → Ø125 (MVHR connection) | VKC5706 | 3 |
| Insulated flexible duct Ø125 (MVHR connections) | FLEX-125-INS | 1.0 m |
| Flexible duct Ø125 (MVHR connections) | FLEX-125-ALU | 1.0 m |
| Jubilee clip Ø125 (MVHR connections) | CLIP-HOSE-125 | 4 |
| 45 deg vertical bend 204x60 | VKC5617 | 4 |
| 45 deg vertical bend 220x90 | VKC5717 | 4 |
| Galvanised banding 12 mm x 10 m reel | CONS-BAND | 4 |
| Red wall plugs (banding) | CONS-PLUG | 88 |
| Screws 4x40 (banding) | CONS-SCREW-4X40 | 88 |
| Duct sealant / silicone 310 ml | CONS-SIL-310 | 4 |
| Aluminium foil tape 50 mm x 50 m | CONS-TAPE | 1 |
| Tec screws 4.2 x 13 (self-drilling) | CONS-TEC | 134 |
SAMPLE
See it in 3D before it goes in
The 3D model of a sample flat's design: the unit, fresh air in blue, stale air in red, the silencers and the fire collars. Yours opens in a browser so you can turn it round.
News
What's changing
Building regulations, England · from 24 March 2027
MVHR commissioning needs a powered flow hood
From 24 March 2027 in England, Approved Document F (2026 edition, paragraph 4.24) requires MVHR and continuous extract (MEV) systems to be commissioned with a powered flow hood, not a vane anemometer. If you're using your own commissioning engineer, ask what they measure with. We commission with a calibrated powered flow hood.
Questions
Before you send your plans
Do I need an MVHR design?
Approved Document F 2021 sets how much air each room needs. A design works out those rates, sizes and routes the ducts so the unit can deliver them quietly, and gives your installer and commissioning engineer the figures they need.
What do you need from me?
Your floor plans as PDFs, with each room's use marked. Section drawings help if you have them.
Can I use my own commissioning engineer?
Yes. Every room's airflow is in your design, and that is what they set each valve to. Or we can commission it for you.
Can I commission it myself?
You can. Building control will want readings taken with a calibrated instrument, and in England from 24 March 2027 that means a powered flow hood. Every room's airflow is in your design to set the valves to, or book our visit.
Where do you commission?
Anywhere in the country. London, Birmingham, Manchester, Leeds, Liverpool, Sheffield, Bristol, Newcastle, Cardiff, Glasgow and Edinburgh are included in the price; anywhere else we add travel at 45p a mile.
Rigid or radial ductwork?
Either. We design rigid ductwork, or a radial system with semi-rigid duct from manifold boxes, and check the noise in every room whichever you choose.
Can you design to Passivhaus?
Yes. We choose a unit certified by the Passivhaus Institute, check it against the Institute's criteria, and give you its certified figures for your PHPP energy model.
How long does it take?
Your full design is back in your account within 48 hours of your plans and details reaching us.
What if my plans change?
Send us the new plans and we redesign it. Your first redesign is free, and each one after that is £39.
Where do I buy the parts?
Anywhere you like. Your parts list names every part with its maker's code, so you can send it to the major suppliers and get an exact price from each.
My house is large. Will one unit do?
Most homes need one unit. Very large homes are better with two or more, one for each zone. We design them all.
Another question? Ask us. Once you've ordered, you can ask your designer on your order page.
Get your design
Create your account and upload your plans
Set up your account, pay for your package, add your PDF drawings and a few details about your home, and your full design is back in your account within 48 hours.