I have had times when my cloner didn't need the heater to be on but I have had plenty of times when it did need to be on to maintain the 78-80f because of trying to keep the air temps in the lower 70s in the space where My cloner sat. The same was the situation with my friend who had his cloner in his central working space of his grow house. He had an AC in that space so that all the air being pulled into the flowering spaces was being taken from the central space that was cooled to 70F. Because of this he had to continually have his heater on in his EZcloner to maintain the 78-80f. I am not saying this is the "only way" to clone, but it is what works best for me and my friend. I used to have a bunch of pics that showed this but I had to destroy them when LEO visited last July. I would imagine though in some cases that the aeroponic pumps would warm the water up considerably but I have not had that problem. In the summers, I have to chill all off my hydro stuff anyway but cloner never got too warm with fan blowing on it