Here is a great controller for these - https://www.hydrogarden.co.nz/shop/New-Products/Cultiv8-Heating-controller/

The Breezin Hot Rod Heat Bars - For grow tents or glass houses

Are by far the safest and most energy efficient option for those looking to maintain optimal greenhouse/growroom temperatures during our long, cold & unforgiving winters. 

The user friendliness and versatility will enable growers to easily hang or mount the heat bars to the walls, floor or even ceiling of their grow/propagation area.
240W – 1200mm length

Increase 5-7°C in 1.2M x 2.4M

Energy Efficient

Safe (no exposed heat elements)
Ideal for green houses & grow tents)
Versitile & User-friendly (Secure to wall or floor)
Durable Steel Shell With Enamel Finish
IP55 (suitable for humid environments)
Compatible With Most Thermostats
One Year Warranty
 PRACTICAL USES INCLUDE:Propagation tents
Large Grow tents
Greenhouses/Growrooms
Additional heat during lights on or lights off 

ADDITIONAL INFORMATION

The Heat Bars are compatible with any digital or analogue thermostat (recommended).
The IP55 water resistant rating ensures safe use in humid environments and the durable enamel finish ensures fire-safety. 
They are constructed with a heating element inside an alloy metal tube with a quality enamel finish.
Includes mounting bracket for easy installation.
Comes with 1 year warranty.