We have a used 110v electric spa that is not heating. We were told that the heating element may be bad. I was wondering if it was possible to use a standard 240v Water Heater Element to replace the current one. It matches in size and threads....

I was told that if you supply 1/2 the voltage to an element, you will get roughly 1/4 the wattage, so:
if a 1500w 120v element, supplied with 110v would get 1500w, then a 6000w 240v element, supplied with 110v power supply would get one quarter of its rated wattage which would be 1500w. This should work right?

What is the differance between a $20 "water" heater element and a $100 "spa" heater element?

Thanks! Rob

How many Ohms of continuety does your existing element read with a multimeter?

The simple answer is "YES" the water heater element will work with your spa. I've done this a couple times just to save money. Here is the kicker. A lot of spa elements have thermowells in them. If yours has this, the water heater element won't, and you won't have a place for your thermostat bulb or your high temp bulb. You can get away with clamping the bulbs to the pipe that the heater goes into, and wrapping it with aluminum foil, but your temperature stability will suffer a couple degrees. Also, most spa heater elements use 1 1/2" NPT threads, and water heater elements use 1 1/4" threads. You can adapt this though. A 6000W 220V element is the same as a 1440W 110 element. A word of adivse, if you do this, make sure you find a way to ground the housing of the new element, and buy the element that has the double loop, not the single loop. You will get a lot better heating out of it. Sure, it's about double the price, but then again, how much is 14 bucks, really, when you are in the bathing suits waiting for the tub to heat?