Hi bubbasnow, There is no problem using 12v parts on a 24v system provided that you limit the current through your heater cartridge and fan. There are instructions here: viewtopic.php?f=7&t=2 Limiting the current of the heater cartridge is extremely important because in a 24v system, the 40W heater cartridge essentially becomes an 80W heater cartridge meaning higher currents and risk of things getting too hot, so if you are at all unsure what you are doing I would advise picking up a 24v heater cartridge from our store. (http://e3d-online.com/24v-RepRap-Heater-Cartridge) Cheers, Josh
