- a suitable box. i am using a plastic kitchen enclosure box which i covered with thin polystrene plates and packaging tape.
- a cheap aquarium heater. i am using a 100w thermostatic one.
- some metres of flexible irrigation pipe.
- a small pond fountain pump.
- a timer socket. (optional)
- 5liters of windshield wiper fluid. (optional)
Just place the thermostatic heater and the pump inside the box and fill it with the heating fluid until it reaches over the pump intake. plug one end of the irrigation pipe to the exit nozzle of the pump and place the pipe as you wish, make sure it covers all the plant area. let the end of the pipe come back inside the box from an opening and let the pump circulate the fluid. I plugged both the heater and pump to a timer socket inside the house and set the timer to activate the heating system at midnight for 7hrs until dawn. I dont use the system during daytime because the sunlight is heating the greenhouse during the day. so the system is automatic. I am using the special wiper fluid instead of tap water because i found out that this fluid is conserving the heat better than water. you can use simple tap water instead. I am also using an insulated plastic box instead of a metal can because this fluid interacts with metal box and the heating fluid is contaminated during long winter months... to maintain a good circulation, keep the pipe as short as possible and more or less at the same level with the container box... my little pump can circulate 5-8 liters of fluid through 10meters of pipe easily...