The installer is standing in front of the heat pump, the fault light is flashing, and the guide is in the office. The apprentice is supposed to clean the machine, but the colleague who showed her how is not in today. The printer on the second floor is on strike, and nobody remembers how to reconnect it.
In all three cases, the guide is not where it is needed. A QR code right on the device solves exactly that: hold up your phone and the guide opens. This guide shows when that pays off, what should be behind the code and what to watch for in terms of size, material and placement.
When a QR code pays off
A QR code is no substitute for good filing. It pays off wherever someone is on site and does not have the instructions in their head:
| Situation | Worth it? | Why |
|---|---|---|
| Fault on a system you rarely see | yes | That is exactly when the knowledge is missing, and you are standing in front of it |
| Maintenance or cleaning at longer intervals | yes | Between two rounds it gets forgotten |
| Devices used by many different people | yes | Temps, apprentices, stand-ins |
| Systems at the customer's site | yes | Technicians change, the customer reads along |
| Task at a desk workstation | rather not | A link or search is faster |
| Daily routine of the same person | no | They know it by heart |
A good rule of thumb: if the typical question is "How did that work again on this device?", it needs a code.
Static or dynamic: the key difference
A QR code only contains an address. What matters is where that address points:
- Static, to a file: The code points directly to a PDF. When the guide changes, the code still points to the old file — or nowhere, once it has been deleted. Then you have to print and stick again.
- Dynamic, to a page you manage: The code points to a fixed address behind which you swap the content. The sticker stays, the guide stays current.
For guides, only the second option makes sense. Be careful with free generators offering "dynamic" codes: many redirect via third-party servers, count the scans or switch the code off after a trial period. If the service disappears, every sticker in the business is dead.
What should be behind the code
- The approved version, not a draft. Whoever stands in front of the machine must be able to rely on it.
- Several guides if needed. A system often needs fault handling, maintenance and operation. One code showing a short choice is better than three stickers next to each other.
- Readable on a phone, without zooming, without an app, without logging in.
- Images with annotations: an arrow on the right switch is worth more on site than any sentence.
- An access code where necessary. If the sticker is at a customer's site or in a public area, not every passer-by should be able to read along.
Size, material, printing
Size. Rule of thumb: the side length of the code should be about one tenth of the reading distance. Scanning from 30 cm needs about 3 cm, from one metre about 10 cm. Below 2 cm it becomes unreliable even up close, especially with older phones.
Quiet zone. The code needs a light margin of four modules (the small squares of the code) around it. Without this margin some cameras will not read the code, especially on a dark background.
Contrast. Dark code on a light background. Coloured or inverted codes look nice but are recognised less reliably.
Material. Ordinary paper lasts in the office. In the workshop, the basement or outdoors you need film or polyester labels that withstand moisture, oil and sun, or a laminated printout.
Label text. Write next to the code what it is for: "Heat pump basement — scan for guide". A code without text gets overlooked or mistaken for advertising.
Test print. Before the big print run, check one sheet on plain paper: are the codes on the labels? Set the print dialog to "Actual size", not "Fit to page".
Placement
- Where you stand when the problem occurs: next to the fault display, not on the back.
- At eye or hand height, not on the floor and not overhead.
- Not on moving parts, flaps or surfaces that get cleaned.
- No reflective surfaces and no acrylic covers in front.
- In the control cabinet: stick it inside if only specialists should read it. Outside with an access code if it should be reachable with the door closed.
Security: stickers can be covered
QR codes in publicly accessible places are sometimes covered with fake codes leading to fraudulent sites ("quishing"). For guides inside the business the risk is small, but three habits help:
- The address behind the code should recognisably belong to your provider.
- Check stickers occasionally, for example during maintenance: is the right code still there?
- No passwords in guides that can be reached via a code, not even with an access code.
Introduced in 5 steps
- Start small. Pick the five devices or systems people ask about most often.
- Write and approve the guides. Short, with photos and annotations. How to do that is explained in How to write work instructions.
- Generate the codes and do a test print. Plain paper first, then labels.
- Attach them and test with several phones, including an older one.
- Ask around. After a few weeks: was the code used? Was anything missing? Then the next devices.
Common mistakes
| Mistake | Consequence | Better |
|---|---|---|
| Code points directly to a PDF | Outdated with the first update | Fixed address, swappable content |
| Free generator with redirect | Code dies with the service | Codes that belong to you |
| Too small or no margin | Not recognised | Reading distance ÷ 10, four-module margin |
| Paper in the workshop | Unreadable after weeks | Film or polyester labels |
| No text next to the code | Gets overlooked | "Device — scan for guide" |
| Draft behind the code | Wrong guide on site | Only approved versions |
Summary
A QR code pays off wherever someone stands in front of the device without the knowledge in their head: for faults, infrequent maintenance and changing people. What matters is that the code points to an address behind which you keep the approved guide current, so the sticker does not go out of date with the first change.