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Frequently asked questions

1. About LeakHunter and pressure testing

What is LeakHunter?

LeakHunter is a compact pressure testing device – also known as a blower door – with an app, developed for carpenters, site managers and airtightness consultants. You fit it in the cooker hood exhaust, the ventilation exhaust or a temporary door panel, enter the building's floor area and start. You can monitor airtightness continuously during construction (Cruise mode) and carry out a documented pressure test to ISO 9972 directly from your phone.

Because it is built to be used every day by the people who build – not just at handover. A traditional blower door requires a door frame, a fabric panel, a laptop and an experienced operator, and is typically used once per project. LeakHunter is set up in 5 minutes, is controlled from your phone, guides a non-specialist through the entire ISO procedure, and the report is ready before you leave the building. It is the ongoing checks during construction that save money – not the final test.

For the people who build. Carpenters and contractors who want to check the vapour barrier themselves before it is closed in – and site managers who want continuous documentation rather than a single measurement at the end. It is also used by airtightness consultants, vocational colleges and building consultants.

At 50 Pa by default – that is the pressure at which requirements are typically set, and the pressure at which leaks are easy to find. In Cruise mode, LeakHunter holds 50 Pa or a pressure of your choice from 1 to 95 Pa; the app shows green when the pressure is reached (±5 Pa of the setpoint) and red when it is not. The ISO 9972 test measures at 7 points from the highest achievable pressure down to 10 Pa, and the result at 50 Pa is calculated from the regression. For the Dutch market, the result at 10 Pa (qv;10) is calculated from the same measurement series.

The method determines how the building's openings are treated during the test. Method 1 – building in use: natural ventilation openings are closed, and mechanical ventilation and cooling are sealed; the building is tested as it is used. Method 2 – building envelope: all intentional openings are sealed, and doors, windows and hatches are closed; this tests the airtightness of the building envelope itself. Method 3 – specific purpose: openings are treated according to the purpose of the test. For documentation under the Danish Building Regulations (BR18), Method 3 is used with the requirement from the building permit – this is also what the Building Regulations themselves refer to, and it is the app's default.

Yes. LeakHunter carries out the test to ISO 9972:2015 with the pressure series the standard requires, in both directions, and the report itself states any deviations from the standard. For the Netherlands, NEN 2686:2025 with qv;10 is also supported, and for the Czech Republic the report can be labelled ČSN EN ISO 9972.

Yes, in Cruise mode you can control the flow yourself from 5–100 % and set the pressure setpoint from 1 to 95 Pa. The ISO test, on the other hand, is automated by design: the app selects the pressure steps and measurement time based on the baseline measurements, so the result does not depend on the operator's judgement. If it is too windy for a valid result, the app tells you – it will not let you "tweak" your way to a result.

What is the difference between a blower door test and LeakHunter?

LeakHunter is a blower door test – just without the door frame, fabric panel and laptop. A traditional blower door is mounted in an external door with a large fabric panel and controlled from a computer. LeakHunter is mounted in a Ø160 mm exhaust duct, controlled from an app, and generates the report on site. The result is the same: the building's leakage airflow at 50 Pa.

Yes. We have an adapter for the Minneapolis Blower Door fabric panel – for both the large and the small opening – so you do not need to buy a new panel. LeakHunter's own frame and fabric panel are on the way.

Cruise mode holds a constant pressure in the building – typically −50 Pa, or a pressure you choose yourself – so you can walk around and find leaks by hand or with a smoke pen, while the figure on the display and in the app shows the building's current airtightness. Green figure = below the requirement, red = more sealing is needed. Cruise mode can be used with or without the app. LeakHunter is built for continuous operation and can hold the pressure for several days, but experience shows that 30–45 minutes of work often reduces leakage significantly.

A LeakHunter test is a quick test at a single pressure point (±50 Pa) with a short report – about 5 minutes, and you can run an unlimited number of them. It is for self-checks during construction – for example before you close the ceiling. An ISO 9972 test follows the standard's full procedure: baseline measurements before and after, 7 measurement points from the highest achievable pressure (max. 65 Pa) down to 10 Pa, and a regression calculation. It produces a report that can be used as documentation for the client and the authorities. Both are carried out in the app; an ISO test in both directions typically takes 15 minutes.

Yes. The direction is determined by how the flexible duct is fitted – on the intake it gives depressurisation, on the outlet it gives pressurisation. The app asks you to confirm that the duct is fitted correctly before the test starts. The ISO 9972 report can be made for depressurisation, pressurisation or both, and Cruise mode works in both directions.

No. LeakHunter carries out the test to ISO 9972 with the full pressure series in both directions – no exemption is required. The report can be used directly as documentation of the airtightness requirement for the local authority and the client.

No. The app guides you step by step through set-up and testing, and video guides and a user manual are built in. We offer a certification course for those who want the formal qualification – see the price list.

2. Requirements, regulations and results

When is a pressure test required?

The Danish Building Regulations (BR18) set requirements for airtightness in new buildings, and the local authority can require documentation in the form of a pressure test to ISO 9972, Method 3. The requirement is stated as leakage airflow per m² of heated floor area at a pressure difference of 50 Pa, and it is given in your building permit.

All three measure how much air leaks out at a pressure difference of 50 Pa – the difference is what they are divided by. qF50 is leakage per m² of heated floor area – the Danish BR18 requirement. qE50 is per m² of building envelope – used when the envelope area is known. n50 is air changes per hour relative to the heated internal volume – used for Passive House. You select the unit in the app, and the result is shown in the unit in which the requirement is set.

An improvement from 1.0 to 0.2 l/s per m² reduces the heating demand by approx. 4–5 kWh/m² per year – an effect that would take a lot of insulation to match. Airtightness costs virtually nothing in materials, only care and checking, and the saving lasts for the entire life of the house.

How airtight does a building need to be?

The standard requirement in the Danish Building Regulations (BR18) is 1.0 l/s per m² of heated floor area at 50 Pa. For the voluntary low-energy class, the requirement is 0.7 l/s per m², and the client can set stricter requirements – Passive House uses n50 ≤ 0.6 air changes per hour, and ambitious projects go down to 0.3 l/s per m². You enter the requirement in the app, and the result is shown green or red against it.

Prices for a pressure test vary widely. An internet search shows prices of DKK 3,000–8,000 per final test when the building passes first time.

With LeakHunter, the cost is quite different – a lower test price, no coordination, and the report immediately instead of after 1–2 days. If the building fails, the difference is far greater: with LeakHunter you retest the same day, whereas an external consultant has to be rebooked with a 1–2 week wait and a risk of delay penalties. Here the value is typically DKK 20,000–100,000 per project.

Yes. The equipment can be used anywhere for preliminary airtightness investigations and anywhere ISO 9972 is applied. The app, the web platform, the reports and the box display are available in Danish, English, German, Dutch and Czech. For the Dutch market, qv;10 to NEN 2686:2025 is supported, and for the Czech Republic the report can be labelled ČSN EN ISO 9972. LeakHunter is in use in Denmark, the Netherlands, the Czech Republic, Ireland and New Zealand.

3. Capacity and technology

How large a building can LeakHunter test?

LeakHunter measures a leakage airflow of up to approx. 200 l/s (approx. 700 m³/h) at 50 Pa. How large a house that corresponds to depends on how airtight it is – the more airtight the building, the larger the area that can be tested:

Airtightness requirement (qF50) Indicative max. heated floor area
1.0 l/s per m² (BR18 standard) approx. 200 m²
0.7 l/s per m² (low-energy class) approx. 285 m²
0.5 l/s per m² approx. 400 m²
0.3 l/s per m² (very airtight) approx. 660 m²

If the building is too leaky to reach 50 Pa, LeakHunter estimates the result from 25 Pa and states this in the report. For larger buildings, a multi-unit function is planned for the end of 2026.

Yes. In very small and airtight rooms (training houses at colleges, single rooms), the flow approaches the lower limit, and the pressure can become difficult to hold stable. The minimum flow should be above 5 l/s.

Where the air has to go out anyway. In the app you choose between cooker hood exhaust, connected ventilation system or no cooker hood (a 160 mm diameter hole in a temporary door or window panel). The 3-meter flexible hose is installed with a 160 mm diameter nipple at each end and clamps.

15 kg in its flight case, 432 × 432 × 400 mm. It runs on standard 230 V (200–240 V, 50/60 Hz) and uses 165 W – an ordinary socket or site power supply is sufficient.

Yes, as with all pressure testing. ISO 9972 requires the baseline measurement (the pressure with the fan switched off) to be within ±5 Pa, and the app retrieves the wind from weather data and records it in the report. Above approx. 6 m/s, the baseline typically becomes too unsteady, the leakage curve imprecise (r² below 0.98), and the report gets a deviation. Move the reference hose to a sheltered spot, or test on another day.

The app retrieves the site address from the phone's GPS and stamps the report "GPS verified". The location is also used to retrieve local wind speed and outdoor temperature, and is only read while you are using the app. It is a quality assurance measure – not a requirement for completing the test. If you correct the address afterwards on the web platform, the GPS mark is removed.

The box continues the test on its own if only the phone loses the connection. If the box loses power, it offers to resume the test from where it stopped when it starts up again – on Pro and Enterprise. The box display shows "Test paused – Resume test". This is worth having on sites with an unstable site power supply.

Can LeakHunter be used for existing, leaky houses – or only new builds?

It can be used for both, but its capacity sets a limit. A very leaky older house may require more air than LeakHunter can move, in which case 50 Pa cannot be held – LeakHunter then estimates from 25 Pa and marks this in the report. In renovation, that is often exactly the point: you find the big leaks first in Cruise mode, and as the house becomes more airtight, you come within the measuring range.

The equipment then gives you a notice about this (see E21/E22 in section 10), and that is a result in itself: the building needs sealing. The measurement does not stop – the app estimates a 50 Pa result from the pressure that can be reached (from 25 Pa) and marks it in the report. Use Cruise mode to find the big leaks first.

A frame with a curtain is then used in a door or window opening—the same principle as a classic blower door. We supply an adapter for the Minneapolis curtain, and LeakHunter’s own frame and curtain are on the way. The flexible hose is 3 m long.

Flow ±7 % and pressure ±1 Pa – within the accuracy requirements of ISO 9972. Every unit is calibrated for both depressurisation and pressurisation against a traceable reference instrument, and a unit is only released once it is within tolerance. The calibration certificate with the measured deviations is available on the web platform.

Yes. LeakHunter measures volume flow directly with a vane anemometer, so the measurement itself is independent of air density. Indoor and outdoor temperatures are included in the ISO correction. Barometric pressure is selected in the app: Standard (101325 Pa), Pa (measured absolute pressure on site) or m (altitude above sea level – the pressure is calculated from the standard atmosphere). Under Danish conditions the effect is small; in mountainous areas it is measurable and is taken into account.

Yes. The test runs locally between LeakHunter and your phone over Bluetooth. Without coverage, you enter the outdoor temperature and wind yourself, and the app shows "Offline — new reports will sync when you're online". The report is sent automatically when the phone is connected again.

That the building is closed (windows, doors, building envelope complete where you are testing), that 230 V is available, that there is a Ø160 exhaust duct or an opening for a frame, and where the ventilation system and exhaust vents terminate, so they can be closed. Ask about open fireplaces/wood-burning stoves, tumble dryers and ventilation systems that cannot be switched off – they must be taped or sealed with balloons, and recorded under Temporarily sealed openings in the report. Check the weather forecast: above approx. 6 m/s wind the measurement becomes unreliable. See the video Preparing the building for testing under Video guides.

4. The app

Which devices does the app work on?

iPhone and Android phones – and iPad and Android tablets. The app is available from the App Store and Google Play.

Yes. leakhunter.dk/manual/da, /manual/en and /manual/de – the same manuals that are built into the app and that the QR code in the lid points to.

This means the app's login has expired and needs to be renewed. In the current app, the report is automatically queued and resent on its own – your data is stored locally. If you still see the error, update the app from the App Store/Google Play and log in again.

When you test several houses on the same project, you can copy all the building data from a previous report and only correct what is different – photo, address, floor area, case number.

Wirelessly from the app under Settings → Update firmware – the same procedure on iPhone and Android. The box must be connected via Bluetooth; on iPhone it must be paired in iOS Settings the first time, and on Android the app must have the "Nearby devices" permission. The update is signed, so only official LeakHunter firmware can be installed. If you have a subscription, this happens automatically. Older units need a one-time cable update at our premises – we do this at the same time as calibration.

Which languages are the app and reports available in?

Danish, English, German, Dutch and Czech – in the app, on the web platform, in the PDF reports and on the box display. The language is selected per user under Settings.

Yes, in Guest mode. You can connect to a box and use Cruise mode with live values, but reports require login. The first login requires an internet connection; after that the app remembers you, even offline.

Reports must be signed by the person who carried out the test. Go to Settings, turn the phone sideways and draw your signature once – it is then added automatically to all your future reports. If you are offline when you save, the signature is stored only on the phone until it has been uploaded.

Yes. In addition to the building photo, you can attach extra photos – e.g. of sealed openings and findings, each with an optional description. The number depends on your subscription – see the subscription overview.

Both. The app is updated via the App Store/Google Play like any other app. The device (the firmware in LeakHunter) is updated wirelessly from the app via Bluetooth, and with a subscription you get new features automatically as soon as they are ready.

5. Subscriptions and prices

How much does LeakHunter cost?

See the current price in the store. The unit comes in a flight case with a 3-meter flexible hose, a coupling, a base plate, air hoses with fittings, a power cable, and a calibration certificate. A sealing kit (tape, pump, blind plugs, and valves) is available for purchase separately.

Four: Free – Cruise mode with live values, no reports. Starter – LeakHunter and ISO reports, user creation, basic web platform, automatic updates. Pro – plus pause/resume during tests and extra photos. Enterprise – plus user roles (Leader/User), report editing, your own logo, more photos and more report storage – and multi-unit and data import when they arrive. Full overview and prices: see the subscription overview and the price list. You can always see your own plan under Subscriptions on the web platform.

No commitment beyond the current period. The subscription renews automatically until cancelled, and cancellation is made in writing to service@leakhunter.dk, effective from the end of the current period.

Per unit. The subscription covers the whole company and is invoiced per active LeakHunter per month – not per registered user. All your units are on the same subscription.

If the test is interrupted by an error (e.g. someone opening an external door), the measurement can be repeated without an additional test being charged. A result that does not meet the requirement is a completed test and is charged as normal.

Yes. We can invoice per case number and with EAN – provide this when your account is set up, and send your case numbers together with the overview of tests.

Yes. We carry out pressure testing and leak detection as a consultancy service – ourselves or through our partner ISOLINK, which has 20 years of experience with blower door tests. See consultancy hours in the price list, or request a quote.

Can I rent a LeakHunter?

Yes. The rental period is 2 weeks at a fixed price of DKK 5,000 including shipping both ways, and access to reporting is included. Tests are charged separately according to the price list – see LeakHunter rental in the shop.

Because you get something a blower door does not provide: the report is generated, stored and can be sent from the site, all your reports and units are gathered on the web platform, the firmware is kept up to date wirelessly, and you can create employee accounts yourself. Cruise mode – the leak detection itself – is always free.

LeakHunter and ISO tests are charged per completed test on top of the subscription – with a discount depending on your subscription (Starter 10 %, Pro 20 %, Enterprise 30 %). Cruise mode is always free. See the price list.

Yes. An upgrade takes effect immediately. A downgrade takes effect from the end of the current subscription period. If you move down from Enterprise, all users automatically become Leaders, so no one loses access to the reports.

Starter up to 100, Pro up to 500, Enterprise up to 1,000 reports. Report storage is backed up, and extra storage can be purchased in packs of 500 reports per year.

Yes. Vocational colleges and educational institutions get special prices, and we are happy to put together a combined agreement covering calibration and subscription for e.g. 3 years, to fit your budget process. Contact us.

6. Calibration, service and warranty

How often does LeakHunter need to be calibrated?

Every two years. The next calibration date is shown under Calibration on the web platform and on page 1 of every report. If the interval is exceeded, it is shown as a deviation in the report – so it is worth keeping to.

You get a date, send the unit in its own case (no extra packaging – close it with a cable tie), and we calibrate it and return it the same day we receive it. During calibration, flow (±7 %) and pressure (±1 Pa) are checked for both depressurisation and pressurisation, the firmware is updated, and you receive a calibration certificate on the web platform. Price: see the price list.

1-year warranty against defects in materials and workmanship. Faults resulting from incorrect use, missing calibration or normal wear and tear are not covered. See the terms of sale and delivery.

By GLS to business addresses and parcel shops in Denmark – next day for items in stock. Delivery abroad by arrangement.

Why does it need calibrating if the fan does not change?

Because it is not the fan we calibrate – it is the measurement chain. According to the manufacturer, the fan delivers almost the same airflow even after many years of use. But the result depends on the vane anemometer and the pressure sensors, and these are what are checked against a traceable reference instrument, so the report can serve as documentation. At the same time, the unit gets new firmware and a service check.

The unit's serial number, date, next calibration deadline, the reference equipment used and the measured deviations in flow and pressure for both pressure directions. The certificate can be downloaded as a PDF under Calibration on the web platform, where you can also see the unit's calibration history.

Yes, there is a 14-day right of return from receipt on unused goods in their original packaging (we sell to businesses only). Subscription periods that have begun are not refunded.

LeakHunter unit, 3 m flexible hose with 2 x Ø160 nipples, 1 Ø160 coupling for possible venting, 1 EB160 end plate with handle, 2 x 5 m air hoses for measuring built-up pressure, including 5 red adapters, 2 m 230 V power cable (C13), and a calibration certificate. The shut-off kit (tape, pump, blind plugs, and valves) is sold separately. If anything is missing, please email service@ with the serial number.

7. Troubleshooting on site

The fan is running at full power, but the pressure reads 0 Pa – what is wrong?

The reference hose is almost certainly not connected. The green hose must be run outside through a hose feed-through so that LeakHunter measures the difference between inside and outside – otherwise it measures outside against outside and sees no pressure. Check the hose at both ends. A very leaky building can give the same picture, but then the figure fluctuates; a completely steady zero is a hose.

ISO 9972 requires the lowest measurement point to be at least 10 Pa above the baseline pressure (and at least 5 times the baseline), with a tolerance of ±3 Pa. In strong wind, the baseline can be so high that the lowest point does not reach this. It is a deviation, not an error – the report is still valid, but the remark is included.

An r² below 0.98 means the leakage curve is not precise enough – typically gusts above 6 m/s, or someone changed something in the building envelope during the test. A flow exponent n outside 0.5–1.0 points to one large leak – an open window, a vent or a duct that has not been closed. Find it in Cruise mode, close it, and test again.

No. The app saves continuously, and the report stays in Offline reports until it can be sent. On Pro and Enterprise, an ISO test can also be paused and resumed. If you still see a report that cannot be retrieved, email the case number to service@ – we can see the measurement on the server.

The app shows "Baseline above ±5 Pa" – what does that mean?

The baseline is the pressure with the fan switched off – the pressure the building has on its own due to wind and temperature. ISO 9972 requires it to be within ±5 Pa. The app shows the worst baseline it measured. Repeat the test on a less windy day, or move the reference hose outside to a sheltered spot.

The highest pressure stayed below 50 Pa because of the building's size or leakiness. The test is still valid to ISO 9972 if at least 25 Pa was reached, but the deviation is shown in the report. Find the big leaks in Cruise mode and test again.

Check that Bluetooth is switched on, that LeakHunter is on, and that you are within a few metres for the first connection. On Android, the app must have the "Nearby devices" permission; on iPhone, the box must be paired in iOS Settings the first time. The app restores the connection itself if it is lost during a test – and the box continues the test on its own in the meantime.

Yes, but the result only tells you about what has been closed. Cruise mode and the LeakHunter test are designed precisely for ongoing checks along the way. The ISO test for handover is carried out when the building envelope is complete. See the video Preparing the building for testing under Video guides.

8. Purchasing, distributors and contact

Where can I buy LeakHunter?

Directly from the shop at leakhunter.dk or through our distributors: Pro Terra / Pro Clima in the Netherlands, Ecological Building Systems in Ireland and Pro Clima NZ in New Zealand. We are happy to arrange a presentation or a demo on your own project first.

Yes, a certification course in using LeakHunter and pressure testing to ISO 9972 (see the price list), and we work with vocational colleges and Videnscenter for Håndværk og Bæredygtighed (Danish Knowledge Centre for Crafts and Sustainability) on an airtightness course.

Can I get a demonstration?

Yes. We are happy to come out to the site and carry out a test with you, so you can see the report on your own building. Book via the contact page.

service@leakhunter.dk or +45 31 72 03 50. Enquiries are normally answered within 2–3 working days. For faults on site: include the report's case number (e.g. 00035-00064) and the unit's serial number, so we can see the measurement straight away.

9. The web platform – user.leakhunter.dk

What is user.leakhunter.dk?

It is LeakHunter's web platform, where your company logs in and sees all reports, units and users in one place. You log in with the same email and password as in the app. Accounts are created by us or by your Leader, and you receive an invitation by email.

The number of reports, how many passed and failed, and the average margin to the requirement – how far below the requirement your results are on average. A quick picture of how airtight you build.

Under Company details → Employee list → Add employee (Leader), or directly in the app. You enter the name, email, mobile number and language, and the employee receives an email with a link to choose a password. The link opens the app when tapped on the phone.

Click the download icon in the report list to download the PDF. The report can then be sent directly to the client or saved locally. Reports can also be downloaded several at a time.

A page where you can drag in a LeakHunter report PDF and get confirmation that it is genuine – bit-identical to the original on our server. If it is, the case number, company, person responsible for the test and date are shown. "No match" means the file has been altered – or that it was generated before we started recording hash values and has not been downloaded since.

Under Company details you drag in the logo (shown at the top right of page 1 of the report, scaled to 190×64 px – wide logos of approx. 3:1 fit best). The logo appears on reports with Enterprise; on other plans it is saved and shown only on the company page.

What can I see and do on the web platform?

That depends on your role. All users see Overview (your test reports with download, search and key figures), Subscriptions (your plan and what it includes), Verify report and Profile. Leaders also see Calibration (units, calibration status and certificates) and Company details (master data, logo and employees). With Enterprise, Leaders can also edit and regenerate reports.

A Leader sees all the company's reports and can manage employees, company details and calibration. A User creates reports and sees only their own. The roles are available with Enterprise – on Starter and Pro, all users are Leaders.

Click Forgot your password? on the login page, or use Forgot password in the app. You will receive an email with a link to reset it. If you do not receive an email, check your spam folder – and email service@ if it is still missing.

Yes, with Enterprise. Click the report and select Regenerate report. You can correct the address, floor area, building data and remarks. Measurement data, method and pressure direction are locked. A new report is created – the original is kept unchanged, and it retains the original tester's name and signature, regardless of who edits it.

All your LeakHunter units with their latest and next calibration, operating hours and firmware version. Click a serial number for the unit's history and download the latest calibration certificate as a PDF.

Company name, address, postcode and town, company registration number (CVR), invoicing email (and EAN, if applicable) and phone number – and for each employee who will use the equipment: name, email and mobile number.

10. Box display and error codes

What does the box display show, and can I use it without the app?

Yes – Cruise mode can be run entirely from the box: enter the area/volume and max. pressure, press confirm, and the display shows pressure, flow and result live. During a test the display follows along: Calibrating → Ready for baseline → Baseline OK / Baseline rejected → Pressure measurement → Waiting for pressure drop → Test complete. The display changes language with your user. ISO reports require the app.

The pressure exceeded the limit you set, and the fan was stopped to protect the building. This typically happens if the building is very airtight or small relative to the fan. Check that doors and windows are closed as planned, lower the max. pressure, or set it to "No limit" if this is intended.

The fan could not create at least 10 Pa. The building is probably too leaky for a valid test, or a larger opening is still open – a window, a ventilation duct, a fireplace. Switch to Cruise mode and find it.

The airflow is below what LeakHunter can measure reliably (5 l/s) – the building or room is very small and airtight. Contact us about set-up for small volumes.

The box lost the connection to its pressure sensor. Restart the box and try again. If the error returns, contact support with the serial number.

What do "Baselines rejected" or "Baseline failed" mean?

The pressure with the fan switched off fluctuated too much – typically wind, or a door being opened. The box automatically offers a second measurement. Wait for a calmer moment, make sure everyone is outside and doors are closed, and start the baseline again.

The measured pressure has the opposite sign to the test direction. Check that the flexible duct is on the correct port (depressurisation or pressurisation), and that no large opening is letting the wind reverse the pressure. The display says "Check air hoses".

The fan reached 10 Pa but could not stabilise at 25 Pa. The building is too leaky for the requested test range. LeakHunter can estimate from 25 Pa, but not below. Seal the big leaks first.

The box lost the connection to the fan. Check the cable between the box and the fan, and restart the box. The error typically clears itself on restart.