Fans: two wires, no soldering
Choosing an extraction fan and wiring it to BudMaster. Get the size right first, then connect it — almost any EC or inline fan takes just two wires and no soldering.
Buyer's guide Size the airflow first
Before you think about wiring, get the size right. The extraction fan is the lungs of your grow space — it pulls out heat and humidity, draws in fresh CO₂, and (through a carbon filter) keeps odour in check. Too little airflow and the space runs hot, damp and stale; too much wastes energy and dries everything out. The aim is the right fan, run at the right speed.
How to size your fan
m³/h ≈ length × width × height (m) × 60 ÷ minutes · or CFM ≈ cubic feet ÷ minutes.
Then size up. A carbon filter, long ducting, bends and a silencer can rob 25–50% of a fan's rated airflow, so pick one rated comfortably above your bare figure and dial it back. An EC fan loafing at 40–60% is quieter and more efficient than a small fan flat out — and leaves headroom for hot weather. Match the duct size to your filter.
| Grow space (approx) | Duct size | Fan airflow ballpark* |
|---|---|---|
| Up to ~0.6 × 0.6 m | 4" (100 mm) | ~180–200 m³/h · 105–120 CFM |
| ~1.0 × 1.0 m | 5–6" (125–150 mm) | ~350–450 m³/h · 200–265 CFM |
| ~1.2 × 1.2 m | 6" (150 mm) | ~450–550 m³/h · 265–325 CFM |
| ~1.5 × 1.5 m or multiple spaces | 8" (200 mm) | ~700+ m³/h · 410+ CFM |
*Rated airflow before filter and ducting losses — size up, then dial down. Heights assumed ~2 m; taller spaces need more.
If your fan has a standard speed input — a 3.5 mm jack, a 0–10 V terminal, or a thin control lead — it connects to BudMaster with two wires and no solder. The only fans you can't speed-control are the ones locked to their maker's own box.
Inline & duct extraction fans Two wires · no solder
Fans fall into four groups by how they connect. The first three are fully plug-and-play.
① Plug-in jack — a 3.5 mm lead
| Brand / model | Connects | Notes |
|---|---|---|
| TerraBloom EC range (6" / 8" / 10", ECMF) | Jack | Speed control on a 3.5 mm audio port (0–10 V / PWM). The fan keeps its own power lead. |
| DucTurbo EC fans | Jack | Same 3.5 mm jack approach — widely documented by the DIY community. |
② 0–10 V terminal — strip and clamp
| Brand / model | Connects | Notes |
|---|---|---|
| Systemair K / KV EC series | Terminal | External 0–10 V input on a terminal block. The grow-trade "Revolution" line is the same fan. |
| Fantech prioAIR EC | Terminal | Built-in 0–10 V control. BudMaster sets the speed. |
| Most commercial 0–10 V EC inline fans | Terminal | The HVAC standard. If it takes a 0–10 V building-management signal, it takes BudMaster. |
③ Flying-lead DC — straight into a terminal
| Fan type | Connects | Notes |
|---|---|---|
| Small 12 V DC inline fans (4") | Channel | Two wires into a channel terminal — BudMaster powers and controls it, full 0–100%. |
| PC case fans (120 / 140 mm, 4-pin) | Channel | 4-pin to bare-wire adapter (no solder), into a channel. Many run off one channel. |
| Larger DC EC fans (24 / 48 V, with a speed pigtail) | 0–10 V | Fan on its own power supply; the speed lead goes into the BudMaster 0–10 V port. |
| The BudMaster fan (coming) | Plug-in | A matched fan with a pre-made lead — true plug-and-play. |
④ AC Infinity — advanced (adapter needed)
| Brand / model | Connects | Notes |
|---|---|---|
| AC Infinity Cloudline (EC) | Adapter | Uses a proprietary "UIS" connector (a USB-C variant) and is built for AC Infinity's own controllers. It can be driven by BudMaster with an adapter, but it's an advanced, unofficial route that may affect warranty. (The EC motor has a 7-wire internal connector; the cheaper plain-DC model has 4.) |
| Fans locked to a "smart bus" with no 0–10 V/PWM input | On/off | No standard speed input to tap. Switch on/off via a smart plug instead. |
How to connect Five steps
Find the speed control
Look for a 3.5 mm socket, a pair of 0–10 V terminals, or a thin control lead that's separate from the power lead. That's the speed input. (A fan with only a mains plug and no speed input can be switched on/off via a smart plug, but not dimmed.)
Match a BudMaster connection
A 3.5 mm lead into the 0–10 V port, a 0–10 V lead clamped into the fan's terminals, or — for a small DC fan — its leads straight into a channel terminal.
Connect two wires
It's always the same two: the speed signal and the ground. Signal to signal, ground to ground. An optional third wire reads the fan's RPM back.
Set it up in the app
Set the channel's role to Fan and run the speed from 0% to 100% to check it responds the right way. If the fan runs backwards — full speed when you ask for off — turn on Invert for that channel.
Done
Set a target, a schedule, or link the fan to temperature and humidity. It now ramps automatically.
Do & don't Keep it simple and safe
- Keep large fans on their own power supply — BudMaster sets the speed, the fan keeps its power.
- Use a fan's jack or terminal where it has one — no cutting, no soldering.
- Check the fan runs the right way and flip Invert if it idles high.
- Wire mains power into BudMaster or into a fan's control input — control signals are low-voltage only.
- Connect a fan's "+10 V" reference wire into a BudMaster input — you only need the signal and the ground.
- Cut the loom on a fan that's under warranty — use the plug-in route instead.
Email hi@budmastergrow.com with the make and model and we'll tell you honestly how it connects. If it has a standard 0–10 V or PWM speed input, it's almost certainly two wires and no solder.
Brand and product names are listed for compatibility guidance only. BudMaster is not affiliated with, endorsed by, or sponsored by these manufacturers, and all trademarks belong to their respective owners. Always check your fan's own manual before wiring. Modifying a third-party product may affect its warranty.