Fan Sizing & Amp Planning
Match your exhaust fan and humidifier to your tent size — and stay inside Hyphae's relay limits.
Exhaust Fan Sizing
Size your exhaust fan for a full air exchange every 3–5 minutes. This gives Dynamic Mode headroom to cycle the fan based on CO2 instead of running it flat out. Modern EC inline fans draw very little power — the fan is never your amperage problem.
| Tent Size | Volume* | Target CFM | Fan Size | Approx. Draw |
|---|---|---|---|---|
| 2×2 to 3×3 ft | ~30–65 ft³ | 15–25 | 4" inline | 0.3–0.5A |
| 4×4 to 5×5 ft | ~110–175 ft³ | 40–60 | 4" inline | 0.3–0.5A |
| 6×6 to 7×7 ft | ~250–345 ft³ | 70–115 | 6" inline | 0.5–0.8A |
| 8×8 to 10×10 ft | ~450–700 ft³ | 140–230 | 6–8" inline | 0.6–1.2A |
| 11×11 to 14×14 ft | ~970–1,570 ft³ | 320–520 | 8–10", or two 6" | 1.0–1.8A |
*Assumes 7–8 ft ceilings. All amp figures are approximate, at 120V.
One Big Fan or Two Small Ones?
For larger rooms, two smaller fans are often the better choice: air moves more evenly across the canopy, you keep partial airflow if one fan fails, and Hyphae's 4-second relay stagger prevents both from starting at the same instant. Two 6" fans draw roughly 1.2–1.6A combined — still a small fraction of one relay group.
Humidification Loads
Most mushroom humidification setups pair an ultrasonic mist maker with a water-resistant 120mm case fan to push fog into the tent. The case fan draws almost nothing; the mist maker heads set the load.
| Tent Size | Mist Maker Heads | Approx. Draw |
|---|---|---|
| 2×2 to 5×5 ft | 4 | ~0.8–1.0A |
| 6×6 to 7×7 ft | 4–6 | ~0.8–1.3A |
| 8×8 to 10×10 ft | 6 | ~1.2–1.5A |
| 11×11 to 14×14 ft | 12 | ~2.3–2.8A |
Includes the 120mm circulation fan (<0.1A). Draw varies by mist maker model — check the label on yours.
Total Load per Tent
Even at the largest tier, exhaust fan plus humidifier totals roughly 4–5A — comfortably inside a single 8–9A relay group. The equipment that does threaten the budget is heat.
Relay Group Planning Rules
- Never exceed 8–9 amps sustained per relay group
- Heaters are the #1 budget risk. A standard 1500W space heater draws 12.5A — too much for any relay group. Use 1000W or smaller, and give the heater its own dedicated group
- Keep fans and lights together in one group (a few amps total), humidification in its own group, and heat in its own group
- Verify every device against the relay's 10A switching capacity, including startup surge on motors and humidifiers
- Hyphae's 4-second delay between relay activations protects against simultaneous startup spikes
- Questions about your specific setup? Ask in our Discord!