Climate & Ventilation — Heating

You can heat in three places and they solve different problems. A cold floor slows uptake even when the air is already up to temperature. A cold room needs warm air. And incoming outside air can be too cold to blow straight onto plants. Which of the three is your problem decides what you need, because the appliances are not interchangeable.

The root zone, and why from below

For germination and cuttings the substrate temperature matters more than the air temperature: a seed responds to the warmth around it in the medium, not to the room. The Secret Jardin heating mat of 20 watts goes under a tray or propagator, measures 55 by 35 cm and is splash-proof to IP64. Often it is the only intervention needed, because a propagator warmed from below does not need a warm room around it.

The air in the room

The AC Infinity ThermoForge S7 is a 1000 W ceramic heater with ten real heat levels, a fresh-air mode and two 100 mm ports, for an open or a closed air loop. Ten levels are more than a comfort feature: a heater that only switches on and off walks your room up and down in a sawtooth. Fertraso has ceramic heaters in 2 and 3 kW with a thermostat, tip-over protection and a cold setting where only the fan runs, keeping the appliance useful in summer.

In the duct, and the condition attached

The Vents duct heaters warm your incoming air before it reaches the room. The NK 100 and NK 125 deliver 1.6 kW, the NK 160, NK 200 and NK 250 deliver 2.4 kW, all rated IP40 and splitting their output across two elements. Read the minimum airflow here, because it heads the specifications for a reason: the NK 100 needs 120 cubic metres per hour and the NK 160 needs 180. An element heating up without air around it is the one genuine risk on this page.

Control does not live here

A heater with its own thermostat regulates itself, but to coordinate heating with extraction you need a climate controller, and those sit under Measuring & Control. Note what one can and cannot do: most switch a fan on temperature and heat nothing.

Frequently asked questions

Can a duct heater run without the fan running?
No. Every model has a minimum airflow and it is a condition, not a recommendation. Always switch the heater together with the fan, never separately.

Heating mat or heater?
A mat when the problem is in the pot, with germination, cuttings and a cold floor. A heater when the room itself is too cold. A mat does not warm the air, and a heater barely lifts a cold concrete floor.

Why does my temperature swing up and down?
Because a heater that only switches on and off always overshoots. An appliance with several power levels holds temperature far more evenly than a more powerful one that cycles harder.