We manufacture heaters. Simple heaters that are designed for a specific voltage, for a specific wattage, thus a fixed resistance and the corresponding amperage. However, sales guys preach that it is OK to hook up the heater to a lower voltage without damaging it. They claim the voltage is lower thus the amperage is lower so although the heater will not function optimally, it will not be damaged. My head says that is correct for Ohm's law but if you look at the Power equation the amperage would be more at the lower voltage thus a problem. Our design uses the power equation when building the heater circuit thus the higher wattage produces the lower amperage. But when designing dual circuit heaters we always design to the higher voltage which does not jive with the power equation but makes sense for Ohm's Law. I see a fixed resistance, although producing heat, the resistance is what it is. I have two groups of people living under two separate equations and I am looking for clarity on which one I should follow for our product.