browndd1 welcome to the GardenWeb. To give the best advice it is important to know where you garden. Most of us put the zone right with your name. Al

Zone 6b Calistoga

2 heaters and a fan sounds a bit overboard to me. Shouldn't need a fan at all. I use some heat in my coldframes but only during very cold nights.

What is it that you are trying to germinate?

I only have one heater in my cold frame and it is a 150 watt element with no fan. The reason I installed a small fan in the cold frame was to distribute the heat and get even temps throughout the cold frame. I st?arted the lettuce and spinach in the house and kept the temps 70f. Therefore, since they were only two weeks old or so, I figured I needed to keep them around 60-70f. What do you think