AC Infinity - SUNCORE S3 Waterproof Seedling Heat Mat 25.4 × 52.7 cm

A 25.4 × 52.7 cm heat mat with a dial for its heat output. The size of a standard seed tray, sealed to IP67, on a 152 cm cord.

A dial sets a level, not a temperature

This is the distinction that matters on this mat. The dial has three positions, low, medium and high, and there is no sensor in it. You decide how much heat the mat gives off, not what temperature it holds.

What happens under your tray is therefore that level plus the room the mat is lying in. In a space that stays much the same day and night, that is easy enough to manage: find the position that works once, and leave it. If the room climbs sharply during the day, the root zone climbs with it, because nothing regulates back.

A cheap thermometer in the medium makes a real difference on this mat. It is the only feedback you have, and one reading tells you straight away whether low or medium is the right position for you.

Prefer the dial to the plug, though. Turning the level down keeps the warmth moving; switching off and on again gives you the jumps that germinating seed copes with badly.

What the mat itself does

Heat comes from infrared film instead of a heating wire, so the whole surface warms and there are no hot strips running under your seeds. The mat works in a band of 26.7 to 30.6 °C and lifts the root zone by up to roughly 11 °C above the temperature of the room.

The outer layer is multi-layer PVC that rolls up and wipes clean, and it stores in the nylon bag supplied. The seams and the cord connection are sealed, so spilled water is not a problem. Submerging it or leaving it outdoors is.

Technical Specifications:

• Model: AC-SMS3
• Dimensions: 25.4 × 52.7 cm
• Control: dial with low, medium and high
• Sensor: none
• Power draw (max.): 20 W
• Band of the mat: 26.7 to 30.6 °C
• Above ambient: up to roughly 11 °C
• Heating element: infrared film
• Outer layer: multi-layer PVC, rollable
• Ingress protection: IP67, seams and cable entry sealed
• Cord length: 152 cm
• In the box: nylon storage bag, bracket and screws for the dial

Frequently asked questions

Can I set a temperature on this?
No, only a level. If you want a value that gets held, the SUNCORE H3 is the same mat in the same size with a controller that measures and regulates.

Does it switch itself off?
No. As long as it has power it keeps giving off heat at the level you chose. There is no timer and no thermostat in it, so pull the plug when you are done.

How many trays fit on it?
One standard seed tray. The mat is built to exactly that size.

Where do I put the dial?
A bracket and screws are supplied to fix it in place, so you are not hunting for it among the trays every time.